Protein powder questions, answered

How much protein do I need per day?

For people who exercise, the ISSN recommends roughly 1.4–2.0 g of protein per kilogram of body weight per day. A meta-analysis of resistance-training studies found gains in muscle mass plateau around 1.6 g/kg/day on average. Protein powder is a convenient way to close a gap, not a requirement.

Sources: International Society of Sports Nutrition Position Stand: protein and exercise (Jäger et al., J Int Soc Sports Nutr, 2017); Protein supplementation and resistance training-induced gains in muscle mass and strength: systematic review and meta-analysis (Morton et al., Br J Sports Med, 2018)

How much protein should be in one serving?

About 20–40 g, or roughly 0.25 g per kilogram of body weight, per the ISSN position stand. Most powders deliver 20–30 g per scoop.

Sources: International Society of Sports Nutrition Position Stand: protein and exercise (Jäger et al., J Int Soc Sports Nutr, 2017)

Does protein powder actually help build muscle?

Yes, when combined with resistance training. A 2018 meta-analysis of 49 trials found protein supplementation significantly increased gains in strength and muscle size, with the effect mattering most when total daily intake was otherwise low.

Sources: Protein supplementation and resistance training-induced gains in muscle mass and strength: systematic review and meta-analysis (Morton et al., Br J Sports Med, 2018)

Does protein timing matter?

Total daily protein intake matters most. The ISSN notes that spreading protein across meals every 3–4 hours is a reasonable strategy, and that the post-workout window is wider than once thought.

Sources: International Society of Sports Nutrition Position Stand: protein and exercise (Jäger et al., J Int Soc Sports Nutr, 2017)

Should I take casein protein before bed?

It is optional. It can help if it raises your total daily protein, but it is not required. Casein digests slowly, which is why it is sold as a bedtime protein. In a 12-week trial, 44 young men doing resistance training took 27.5 g of casein or a calorie-free placebo before sleep. The casein group gained more strength and more quadriceps muscle size. However, that group also ate more protein overall, so the result supports extra total protein at least as much as the timing. Sports nutrition guidance says total daily protein matters most, spread across meals every 3 to 4 hours. A pre-sleep serving is an easy way to reach that total, and it does not have to be casein: a serving of Greek yogurt or cottage cheese provides mostly casein as well.

Sources: Snijders et al. (2015), Protein ingestion before sleep increases muscle mass and strength gains during prolonged resistance-type exercise training in healthy young men, J Nutr; International Society of Sports Nutrition Position Stand: protein and exercise (Jäger et al., J Int Soc Sports Nutr, 2017)

Can I mix creatine with my protein shake?

Yes. Creatine monohydrate can be stirred into a protein shake, and taking it with protein and carbohydrate may help your body retain slightly more of it. The International Society of Sports Nutrition calls creatine monohydrate the most effective supplement available for high-intensity exercise capacity and lean mass, and considers it safe at recommended doses for healthy people. Its position stand notes that taking creatine with carbohydrate, or carbohydrate plus protein, can raise how much creatine the muscles retain, though this does not necessarily improve performance. In one study, 5 g of creatine taken with about 50 g of protein and 47 g of carbohydrate was retained as well as when taken with about 100 g of carbohydrate. The usual maintenance dose is 3 to 5 g a day. Taking it daily matters more than the exact time of day.

Sources: Kreider et al. (2017), International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine, J Int Soc Sports Nutr; Steenge et al. (2000), Protein- and carbohydrate-induced augmentation of whole body creatine retention in humans, J Appl Physiol

How much protein do older adults need, and is protein powder useful for them?

Expert groups recommend more protein for people over 65 than the standard adult RDA of 0.8 g per kg of body weight. The PROT-AGE study group recommends 1.0 to 1.2 g/kg a day for healthy adults over 65, at least 1.2 g/kg for those who exercise, and 1.2 to 1.5 g/kg for those with acute or chronic illness. People with severe kidney disease who are not on dialysis are an exception and need less. They also suggest spreading protein across meals, with about 25 to 30 g per meal. Protein powder is not required, but it can help an older adult who has a small appetite or finds it hard to chew meat. Choose a third-party tested product, and talk to a doctor first if you have kidney disease or other medical conditions.

Sources: Bauer et al. (2013), Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group, J Am Med Dir Assoc; Institute of Medicine (National Academies): Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, ch. 10 Protein and Amino Acids (2005); NIDDK (NIH): Protein Tips for People with Chronic Kidney Disease

Do runners and endurance athletes need protein powder?

No, but it can help them hit their protein targets. A joint position stand from the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine puts athletes' needs at about 1.2–2.0 g of protein per kilogram of body weight per day. That covers endurance and strength athletes alike. It advises about 0.3 g/kg (roughly 15–25 g) after key sessions and every 3 to 5 hours across meals. Food can cover all of that. A shake is simply a convenient way to get 20 g or so after a long run when you have no appetite or no time to eat.

Sources: Thomas, Erdman & Burke (2016), Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance, J Acad Nutr Diet

I have never bought protein powder before. What should I look for?

Start with four checks. First, make sure you need it: the RDA is 0.8 g of protein per kilogram of body weight a day, and a powder only makes sense if food alone leaves you short. Second, pick a type that fits your diet: whey if you tolerate dairy (isolate if lactose bothers you), or a plant or egg protein if you don't, and check the "Contains" line for allergens. Third, look for a named third-party certification such as NSF Certified for Sport, because the FDA does not approve supplements before they are sold. Fourth, compare the cost per gram of protein, not the price of the tub. A plain or lightly sweetened powder from a single protein source is the easiest place to start.

Sources: Institute of Medicine (National Academies): Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, ch. 10 Protein and Amino Acids (2005); U.S. Food & Drug Administration: Dietary Supplements; NSF Certified for Sport: What Our Mark Means; FDA: Food Allergies (the nine major food allergens and how they must be labeled)

Whey isolate vs. whey concentrate: which is better?

Isolate is filtered further, so it has more protein per gram and less lactose, fat, and carbohydrate — better for lactose-sensitive people and those tracking macros. Concentrate is cheaper and perfectly effective. Both are complete, high-leucine proteins.

Is plant protein as good as whey?

Well-designed plant blends (e.g. pea + rice) can provide a complete amino acid profile, though they are typically somewhat lower in leucine per gram than whey, so a slightly larger serving closes the gap. Because testing has found higher heavy-metal levels in some plant powders, third-party certification matters even more for plant products.

Sources: International Society of Sports Nutrition Position Stand: protein and exercise (Jäger et al., J Int Soc Sports Nutr, 2017); Consumer Reports: High Levels of Lead in Protein Powder and Shakes (2024)

Does collagen protein count toward my daily protein goal?

Partly. Collagen's grams count as protein, but it is an incomplete protein: it contains no tryptophan, an essential amino acid, so its protein-quality score is zero. It is also low in leucine, which drives muscle building. In a trial in older women, 30 g a day of whey raised muscle protein synthesis while 30 g of collagen did not do so at rest. A diet analysis found collagen can make up as much as 36% of daily protein while still meeting essential amino acid needs, as long as the rest comes from complete proteins such as dairy, eggs, meat, soy or a mixed plant diet. So count collagen toward your total, but do not rely on it as your main protein for muscle, and do not swap it in for whey one-for-one.

Sources: Significant amounts of functional collagen peptides can be incorporated in the diet while maintaining indispensable amino acid balance (Paolella et al., Nutrients, 2019); Whey protein but not collagen peptides stimulate acute and longer-term muscle protein synthesis with and without resistance exercise in healthy older women (Oikawa et al., Am J Clin Nutr, 2020)

Is egg white or beef protein powder as good as whey?

Egg white protein is a high-quality, complete protein and a good dairy-free alternative to whey. Beef protein isolate is less certain and depends on the product. In a lab analysis of commercial proteins, whey had the most essential amino acids (43%) and leucine (11%); egg protein had 32% essential amino acids and 7% leucine. So you need somewhat more egg protein than whey to get the same leucine, roughly 35 to 40 g instead of 25 g. Many beef protein isolates are made largely from collagen (hide, bone and connective tissue). Some brands publish amino acid profiles with about 10% hydroxyproline, a collagen marker, and only about 4% leucine, which is closer to collagen than to muscle meat. There is little research on beef isolate: one small 8-week conference study found similar lean-mass gains with beef and whey isolate and no difference in strength. Before you buy beef protein, check the brand's amino acid profile for leucine.

Sources: Gorissen et al. (2018), Protein content and amino acid composition of commercially available plant-based protein isolates (includes whey, casein, milk and egg), Amino Acids; Kono Nutrition, Amino acid profiles: beef vs. whey isolate (manufacturer-published beef protein amino acid table); Sharp et al. (2015), The effects of beef protein isolate and whey protein isolate supplementation on lean mass and strength in resistance trained individuals (conference abstract), J Int Soc Sports Nutr

Is yeast protein as good as whey?

Early evidence suggests yeast protein can support muscle about as well as whey, but there is much less research on it. In a 6-month randomized trial, 92 older adults with early muscle loss took whey protein, yeast protein or nothing. Both protein groups improved walking speed and physical-performance scores more than the control group. A few industry-funded trials in younger adults report similar results, but no published tracer study yet compares how fast yeast and whey build muscle protein. Whey also has more of the amino acid leucine than most other proteins. Yeast protein is dairy-free, which is its main advantage for people who avoid milk. Check that a yeast protein product is third-party tested, as you would for any powder.

Sources: Huijing et al. (2026), The impact of oral whey protein and yeast protein supplementation for 6 months on skeletal muscle mass, strength, and function in the elderly: a randomized, controlled, parallel study, Food Sci Nutr; Gorissen et al. (2018), Protein content and amino acid composition of commercially available plant-based protein isolates (includes whey, casein, milk and egg), Amino Acids

What is the difference between whey protein and milk protein?

Milk protein is both of milk's proteins together: about 80% casein and 20% whey, the same ratio as in milk. Whey protein is only the 20% fraction. Milk protein concentrate and isolate are made by filtering milk, so they keep that 80:20 ratio. MPC 80, for example, is about 80% protein with 5–6% lactose. Because it is mostly casein, milk protein digests more slowly and mixes thicker. Whey digests faster and has more leucine: in a lab analysis, whey protein was 11% leucine and milk protein 9%. Both are complete, high-quality dairy proteins. Milk protein is usually cheaper, while whey isolate is lower in lactose. Your total daily protein matters more than which one you choose.

Sources: U.S. Dairy Export Council, Milk protein concentrate; Gorissen et al. (2018), Protein content and amino acid composition of commercially available plant-based protein isolates (includes whey, casein, milk and egg), Amino Acids; International Society of Sports Nutrition Position Stand: protein and exercise (Jäger et al., J Int Soc Sports Nutr, 2017)

What is clear whey protein, and is it different from regular whey?

Clear whey is whey protein isolate that has been acidified so it mixes into a thin, see-through drink like juice instead of a milky shake. Clear acidic protein drinks use whey isolate because it stays dissolved at an acidic pH of about 3.3, so clear whey drinks are tart and usually fruit-flavored. Nutritionally, it is still whey isolate: the same complete dairy protein, with very little lactose. Some brands also hydrolyze it, but clarity comes mainly from the low pH and a high-purity isolate. The main downside is taste: food scientists have traced a soapy off-flavor in some acidic whey drinks to fatty acids left in the protein. Clear whey is often priced higher than regular isolate, so compare it by cost per 25 g of protein, as you would any other powder.

Sources: Sources of soapy off-flavor in clear acidic whey protein beverages (2025), J Food Sci; U.S. Dairy Export Council (ThinkUSAdairy): Whey Protein Isolate typical composition

Is soy protein as good as whey for building muscle?

For long-term muscle and strength gains, the evidence so far finds no difference. A 2018 meta-analysis of 9 resistance-training studies of 6 weeks or longer (266 participants) found that soy and whey, or soy and other animal proteins, produced similar gains in lean mass and in bench press and squat strength. In the short term, whey does have an edge. In a 2009 lab study of young men, whey raised blood leucine more than soy and stimulated more muscle protein synthesis after exercise, likely because of its higher leucine content and faster digestion. Over weeks of training, that difference did not show up in measured gains, so soy is a reasonable choice, especially if you avoid dairy; compare brands by cost per 25 g of protein. One disclosure: the lead author of the 2018 review directs a soy industry group.

Sources: Messina et al. (2018), No difference between the effects of supplementing with soy protein versus animal protein on gains in muscle mass and strength in response to resistance exercise, IJSNEM; Tang et al. (2009), Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men, J Appl Physiol

Is a mass gainer bad, or is it just whey plus extra calories?

A mass gainer is not bad. It is mostly protein powder plus a large dose of carbohydrate. One popular gainer lists 1,250 kcal per 334 g serving: 50 g of protein, 252 g of carbohydrate (20 g of it sugars) and 4.5 g of fat. Its first ingredient is maltodextrin, followed by a whey, casein and egg protein blend. So the protein is ordinary; the difference is the carbohydrate calories. That suits someone who struggles to eat enough to gain weight. If you can eat more food, whey plus milk, oats or a meal gives the same calories with more control over what they are, and usually costs less per gram of protein. Weigh a gainer by its protein per serving and cost per 25 g of protein, not by its calories alone.

Sources: Optimum Nutrition Serious Mass label (chocolate, 12 lb), as listed by DPS Nutrition

Is grass-fed whey worth it?

"Grass-fed" describes how the cows were fed, not how pure the powder is or how much protein it has, and on most tubs it is not independently verified. There is no federal standard for a grass-fed dairy claim: the USDA withdrew its voluntary grass-fed marketing standard in January 2016, which leaves the definition up to each producer. If grass-fed matters to you, look for a third-party certification such as the American Grassfed Association, whose standards cover dairy cattle and require animals to get their nutrition from grazing pasture, with no antibiotics, ionophores or hormones. Either way, a grass-fed claim is not a substitute for third-party testing for contaminants and label accuracy, so check for a named testing program as well.

Sources: Cornucopia Institute: The Facts About the USDA AMS Grassfed Marketing Claim Rescission (2016); American Grassfed Association: Our Standards; NSF Certified for Sport: What Our Mark Means

Where does whey protein come from, and how is protein powder made?

Whey comes from milk: it is the liquid left over when milk is made into cheese. Cheesemakers add bacteria and enzymes, which make the casein proteins in milk curdle, and when the curd is cut the whey drains off. That liquid holds most of the milk's lactose and minerals and its soluble whey proteins. Processors then pasteurize it and use membrane filtration (ultrafiltration) to keep the larger proteins and let lactose, minerals and water pass through, then evaporate and spray-dry it into powder. Whey protein concentrate (WPC) typically contains 34% or more protein, and whey protein isolate (WPI) is filtered further to 90% or more protein. Brands then blend the base powder with flavors, sweeteners and thickeners.

Sources: U.S. Dairy Export Council: Whey Protein and Ingredients, Common Questions; USDA AMS: Whey Protein Concentrate Technical Report (2015)

Do protein shakes help with weight loss?

They can help a little, but only as part of eating fewer calories overall. A protein shake does not burn fat by itself. A 2012 meta-analysis of 24 trials (about 12 weeks each) compared calorie-cut diets higher in protein (about 1.25 g per kg of body weight a day) with standard-protein diets (about 0.72 g/kg). The higher-protein diets led to slightly more weight loss (0.79 kg more) and fat loss (0.87 kg more), kept more lean mass, and reduced the drop in resting energy use. Those effects are modest. A shake is simply a convenient way to raise protein while you cut calories. Its calories still count, so a shake added on top of your usual meals can make you gain weight rather than lose it.

Sources: Wycherley et al. (2012), Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials, Am J Clin Nutr

Can I replace a meal with a protein shake?

Plain protein powder mixed with water is not a complete meal. It is mostly protein, with little of the fiber, vitamins, minerals, carbohydrate or fat a meal provides. The research on meal replacement uses fortified, calorie-controlled meal-replacement products, not plain protein powder. A pooled analysis of six studies found that replacing one or two meals a day with such products produced about 2.5 kg more weight loss at 3 months than a standard reduced-calorie diet. At one year the difference was similar (2.4 kg) but no longer statistically significant. If you use protein powder in place of a meal, make it closer to a meal: blend it with milk or soy milk, fruit, oats or nut butter. Do not replace most of your meals this way without a doctor or dietitian.

Sources: Heymsfield et al. (2003), Weight management using a meal replacement strategy: meta and pooling analysis from six studies, Int J Obes

Are protein shakes safe for people with diabetes?

Usually, yes, if you count the shake's carbohydrate and calories and your doctor or dietitian agrees. Plain whey or plant protein powder is low in sugar, but many ready-to-drink shakes and mass gainers contain a lot of it, so read the label. The American Diabetes Association does not set one protein target for people with diabetes; typical intake is 0.8–1.5 g per kg of body weight a day, adjusted to the person. In a small trial in men with type 2 diabetes, 15 g of whey taken just before breakfast and lunch lowered the rise in blood sugar after breakfast by about 13%. That is a short-term research finding, not a treatment, and it does not replace diabetes medicine. If you have diabetic kidney disease, ask your doctor how much protein is right for you, because the target may be lower.

Sources: American Diabetes Association (2026), 13. Older Adults: Standards of Care in Diabetes, Diabetes Care; King et al. (2018), A small dose of whey protein co-ingested with mixed-macronutrient breakfast and lunch meals improves postprandial glycemia and suppresses appetite in men with type 2 diabetes, Am J Clin Nutr; NIDDK (NIH): Protein Tips for People with Chronic Kidney Disease

What is the best protein powder for keto or a low-carb diet?

Look for a whey isolate or another low-carb isolate, and check the total carbohydrate on the Nutrition Facts panel. Whey isolate is at least 90% protein with very little lactose, so unflavored isolates are often very low in carbohydrate. Concentrates, blends, and powders with added sugar, maltodextrin or oats can have far more. "Net carbs" on the front of the tub is not a term the FDA defines, and brands calculate it in different ways. The American Diabetes Association advises reading total carbohydrates first. Sugar alcohols such as erythritol count toward total carbohydrate on the label even when a brand subtracts them. Because flavors differ, check the label of the exact flavor you buy, then compare by cost per 25 g of protein.

Sources: U.S. Dairy Export Council (ThinkUSAdairy): Whey Protein Isolate typical composition; American Diabetes Association: Making Sense of Food Labels

Is whey protein halal?

It depends on how the whey was made, so check for a halal certification rather than assuming. Whey is a by-product of cheesemaking, and the American Halal Foundation says whey is halal if it comes from milk processed with microbial enzymes or halal-certified rennet; whey made with enzymes from non-halal sources, such as pigs, is not. Certifiers also review the gelatin, enzymes and other additives in the finished powder, and halal rules exclude pork derivatives and alcohol. A brand saying its whey uses microbial rennet is a good sign but is not the same as certification. The reliable check is a halal certification mark on the specific product (certification can differ by flavor and country), or certification details on the manufacturer's website. Plant proteins such as pea or rice avoid the rennet question but still need the additives checked.

Sources: American Halal Foundation: Is Protein Powder Halal?

How do I find a soy-free protein powder?

Read the allergen statement. Soy is one of the nine major food allergens in the U.S., and the FDA requires its source to be named on the label, either in a "Contains" statement (such as "Contains: milk, soy") or in parentheses in the ingredient list, and this applies to dietary supplements. Soy often shows up in powders that are not soy protein, most commonly as soy lecithin added to help the powder mix, so a whey or pea powder can still say "Contains soy." Look for no soy in the Contains line and no soy lecithin in the ingredients; sunflower lecithin is a common soy-free substitute. "May contain" or "made in a facility with" statements are voluntary and are not required by law, so their absence does not prove there is no cross-contact; if you have a soy allergy, ask the manufacturer.

Sources: FDA: Food Allergies (the nine major food allergens and how they must be labeled)

Is protein powder gluten-free, and how do I find one that is safe for celiac disease?

Plain whey, casein, egg, pea and rice protein do not contain gluten as ingredients, but a finished powder can pick it up from added ingredients or cross-contact, so look for a gluten-free claim or certification. In the U.S. a "gluten-free" label is voluntary, but if a product uses it, including a dietary supplement, the FDA requires it to contain less than 20 parts per million (ppm) of gluten. The Gluten-Free Certification Organization (GFCO) logo is stricter: it requires the product and its ingredients to test below 10 ppm, or the country's threshold if lower. Wheat must be declared as an allergen, but barley and rye are not major allergens, so also check the ingredient list for barley malt and similar ingredients, which sometimes appear in cookie or cereal flavors.

Sources: FDA: Questions and Answers on the Gluten-Free Food Labeling Final Rule; Gluten-Free Certification Organization (GFCO); FDA: Food Allergies (the nine major food allergens and how they must be labeled)

How do I find a dairy-free protein powder?

Choose a plant protein (such as pea, rice, soy, hemp or a blend) or egg white protein, and confirm that the "Contains" line does not list milk. Whey and casein are both milk proteins, and the FDA requires milk to be named on the label, for example as "whey (milk)" or in a "Contains: milk" statement, including on dietary supplements. "Lactose-free" is not the same as dairy-free: whey isolate is low in lactose but is still milk protein. That matters because, as the NIH explains, a milk allergy is an immune system disorder and is different from lactose intolerance, which is about digesting milk sugar. "May contain milk" warnings are voluntary, so if you have a milk allergy, check with the manufacturer about cross-contact.

Sources: FDA: Food Allergies (the nine major food allergens and how they must be labeled); NIDDK (NIH): Definition & Facts for Lactose Intolerance

Is whey protein kosher?

Only if the specific product is kosher-certified, so look for a kosher symbol from a recognized agency on the tub rather than judging from the ingredient list. Whey is a by-product of cheesemaking, and the OU (Orthodox Union) explains that even though whey is not cheese, it is not free of kosher issues: every ingredient in the cheese vat the whey is drawn from (rennet, cultures, lipase and more) must be kosher, whey from cheeses made at very high vat temperatures, such as traditional Parmesan and Swiss, usually cannot be certified, and equipment that handles non-kosher cheese cooker water cannot be shared with whey processing. Kosher whey is milk-based, so it counts as dairy for anyone keeping meat and dairy separate.

Sources: OU Kosher: Whey (Behind the Union Symbol)

How do I find a protein powder that is safe for a peanut or tree nut allergy?

Read the "Contains" line first: peanuts and tree nuts are major food allergens, and the FDA requires them to be declared on the label, including on dietary supplements, so a powder with nut butter, nut flour or nut flavoring must say so. Cross-contact is harder. Statements such as "may contain" or "made in a facility that also processes peanuts" are voluntary, so a label without one is no guarantee that the powder was made on nut-free equipment. If your allergy is severe, contact the manufacturer and ask whether the product is made on lines shared with peanuts or tree nuts, and how they clean between runs.

Sources: FDA: Food Allergies (the nine major food allergens and how they must be labeled)

Is protein powder regulated or tested by the FDA?

No. In the U.S., protein powders are sold as dietary supplements or foods, and the FDA does not approve them for safety or effectiveness before sale. This is why independent third-party certification is the first thing to check.

Sources: U.S. Food & Drug Administration: Dietary Supplements

What is amino spiking?

Adding cheap free amino acids (like glycine or taurine) to a powder so that a nitrogen-based protein test reports more protein than the product really contains as intact protein. Check the ingredient list for free amino acids listed separately from the protein sources.

Should I be worried about heavy metals in protein powder?

It is worth checking, especially if you use powder every day. Consumer Reports' 2025 tests found that more than two-thirds of 23 protein powders and shakes had more lead per serving than its experts' daily level of concern (0.5 micrograms), some by more than 10 times. The Clean Label Project's 2025 study of 165 top-selling powders found 47% exceeded at least one federal or state limit for heavy metals. The FDA says there is no known safe level of lead exposure, and Consumer Reports notes that lead builds up in the body, so repeated daily exposure matters most. Consumer Reports advises against daily use of most protein powders, and suggests limiting servings per week and getting protein from whole foods where you can.

Sources: Consumer Reports: Protein Powders and Shakes Contain High Levels of Lead (2025); Clean Label Project: Nearly Half of Top-Selling Protein Powders Exceed Safety Thresholds for Heavy Metal Contamination (2025); U.S. Food & Drug Administration: Lead in Food and Foodwares

How do I find a protein powder that is low in heavy metals?

Look for a brand that publishes heavy-metal test results for its products; Consumer Reports notes that few do. If you can't find results, Consumer Reports suggests choosing a dairy-based protein such as whey over plant-based, and avoiding products that carry a California Prop 65 warning, especially for children and people who are or could become pregnant. Flavor matters too: the Clean Label Project found chocolate powders had 110 times more cadmium than vanilla ones, and 65% of chocolate products were over the Prop 65 lead level. Independent contaminant testing (for example, Clean Label Project certification) is a further check.

Sources: Consumer Reports: Protein Powders and Shakes Contain High Levels of Lead (2025); Clean Label Project: Nearly Half of Top-Selling Protein Powders Exceed Safety Thresholds for Heavy Metal Contamination (2025)

Do plant-based protein powders have more heavy metals than whey?

On average, yes, in recent independent testing. Consumer Reports (2025) found plant-based products averaged nine times the lead of dairy-based ones like whey. The Clean Label Project (2025) found 77% of plant-based powders were over the California Prop 65 lead level, versus 28% of whey powders, and that plant-based powders had five times more cadmium than whey. Certified-organic products averaged three times the lead of non-organic ones, mainly because most of them were plant-based. Plants take up whatever contaminants are in the soil. These are averages, so some plant powders test low; look for one whose maker publishes heavy-metal results.

Sources: Consumer Reports: Protein Powders and Shakes Contain High Levels of Lead (2025); Clean Label Project: Nearly Half of Top-Selling Protein Powders Exceed Safety Thresholds for Heavy Metal Contamination (2025); U.S. Food & Drug Administration: Lead in Food and Foodwares

Why is lead in protein powder a bigger concern than lead in other foods?

Mostly because of how often people use it. Lead gets into many foods from soil and the environment, and the FDA says it is not possible to keep it out of the food supply entirely. But Consumer Reports points out that protein powder is a daily habit for many people, unlike an occasional treat such as chocolate. Lead accumulates in the body, so small daily doses add up. The FDA says there is no known safe level of lead exposure, and children and pregnant people are most vulnerable because lead can harm the developing brain and nervous system. Supplements are also not approved by the FDA before sale, so independent testing is the main outside check.

Sources: Consumer Reports: Protein Powders and Shakes Contain High Levels of Lead (2025); U.S. Food & Drug Administration: Lead in Food and Foodwares; U.S. Food & Drug Administration: Dietary Supplements

What does "third-party tested" actually mean on a protein powder?

It means an organization independent of the brand tested the product, but the words alone don't tell you what was tested or how often. The phrase isn't a regulated term, and the FDA doesn't approve supplements before they are sold, so look for a named certification you can check. The main programs: NSF Certified for Sport checks that the label matches the contents, that there are no unsafe levels of contaminants, and that the product contains none of 290 substances banned in sport, and it audits the factory. Informed Sport tests every batch for more than 285 banned substances before release. BSCG Certified Drug Free tests every lot for more than 450 drugs and checks label claims and contaminants once a year. Clean Label Project focuses on contaminants such as heavy metals. A bare "third-party tested" claim with no named program or lookup is the weakest version.

Sources: NSF Certified for Sport: What Our Mark Means; LGC Informed Sport: Informed Sport vs Informed Choice; BSCG: Certified Drug Free Certification and Testing for Banned Substances; Clean Label Project: Nearly Half of Top-Selling Protein Powders Exceed Safety Thresholds for Heavy Metal Contamination (2025); U.S. Food & Drug Administration: Dietary Supplements

What is the difference between NSF Certified for Sport, Informed Sport, Informed Choice and BSCG?

All four screen for substances banned in sport, but they differ in how often they test and what else they check. NSF Certified for Sport screens for 290 banned substances, verifies the label matches the contents, tests for contaminants and audits the manufacturing facility once or twice a year. Informed Sport tests every batch for more than 285 banned substances before it goes on sale, then retests products bought at retail. Informed Choice, run by the same company (LGC) with the same methods, buys products at retail and tests at least 12 random batches a year, so not every batch is covered. BSCG Certified Drug Free tests every lot for more than 450 drugs, including over 400 on the WADA list, and verifies label claims and contaminants once a year. If you are a drug-tested athlete, a program that tests every batch is the stricter choice; for everyone else, any of them is a real check beyond the brand's own word.

Sources: NSF Certified for Sport: What Our Mark Means; LGC Informed Sport: Informed Sport vs Informed Choice; BSCG: Certified Drug Free Certification and Testing for Banned Substances

How do I check that a protein powder's certification is real?

Look the product up in the certifier's own database, not just the logo on the tub, since a logo can be printed on any label. NSF has a Search Certified Products tool and app at nsfsport.com. Informed Sport lets you search by product and batch number at sport.wetestyoutrust.com (or in its app), and Informed Choice has its own search at choice.wetestyoutrust.com. BSCG lists certified products in its Certified Drug Free database. For programs that certify by batch or lot, match the lot number printed on your container to the database entry. If the product, flavor or batch isn't listed, treat the claim as unverified.

Sources: NSF Certified for Sport; LGC Informed Sport: Informed Sport vs Informed Choice; BSCG: Certified Drug Free Product Database

How do I know if my protein powder is legit and not a counterfeit?

Buy from the brand or a retailer it authorizes, and check the seller and the packaging when it arrives. Consumer Reports' signs of a fake include a third-party seller you can't identify, a price well below what authorized retailers charge, and anonymous packaging without the brand's logos. If the product claims a certification, look up its lot number in the certifier's database. If you think a product made you ill, report it to the FDA. The FDA also keeps a Health Fraud Product Database of products with hidden drug ingredients, which are usually bodybuilding, weight-loss and sexual-enhancement products rather than plain protein powder.

Sources: Consumer Reports: How to Avoid Buying Counterfeit Products Online (2018); Federal Trade Commission: Buying From an Online Marketplace; U.S. Food & Drug Administration: Health Fraud Scams; LGC Informed Sport: Informed Sport vs Informed Choice

Is it safe to buy protein powder on Amazon or other online marketplaces?

It can be, if you check who is actually selling it. On Amazon, look at the "Ships from and sold by" line; on Walmart.com, "Sold and shipped by." Consumer Reports says the lowest risk is when the brand itself, or the marketplace, is the seller; a third-party vendor is where fakes most often come from, especially one offering a new product below the established price. The FTC advises checking the seller's ratings and recent reviews across several sources, because some reviews are fake, and paying by credit card so you can dispute a charge if something goes wrong. For something you will eat every day, buying direct from the brand or an authorized retailer is the safest option.

Sources: Consumer Reports: How to Avoid Buying Counterfeit Products Online (2018); Federal Trade Commission: Buying From an Online Marketplace

Do kids need protein powder?

Usually not. Most children get enough protein from food: the U.S. Recommended Dietary Allowance is 13 g a day for ages 1–3, 19 g for ages 4–8 and 34 g for ages 9–13, which a varied diet usually covers. The American Academy of Pediatrics says young athletes who eat a balanced diet do not need protein supplements, and warns that supplements are not checked by the FDA before sale and are sometimes contaminated. A kids' nutrition shake can make sense for a very picky or restricted eater or a child with growth concerns, but only with a pediatrician's guidance. If you do buy one, pick a product made for children with low added sugar, no caffeine or stimulants, and independent testing.

Sources: Institute of Medicine (National Academies): Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, ch. 10 Protein and Amino Acids (2005); American Academy of Pediatrics, HealthyChildren.org: Performance-Enhancing Sports Supplements: Information for Parents; American Academy of Pediatrics, HealthyChildren.org: Nutritional Supplements, Vitamins & Boosting Your Child's Immunity

Can I use protein powder while pregnant?

Ask your OB, midwife or doctor first; they know your pregnancy. Protein needs rise in pregnancy: the U.S. Recommended Dietary Allowance is 1.1 g per kg of body weight a day, set on the basis of an extra 25 g a day, and newer research suggests needs may be higher later in pregnancy. A powder can be one option when nausea, food aversions or a small appetite make protein foods hard. If you use one, check four things on the label. Independent testing for heavy metals: Consumer Reports found more lead than its experts consider safe for a day in one serving of more than two-thirds of the protein powders and shakes it tested, with plant-based products higher on average. Caffeine: ACOG says moderate caffeine, less than 200 mg a day, does not appear to be a major factor in miscarriage or preterm birth, and some coffee- or tea-flavored powders add caffeine. Herbs and botanicals: the NIH Office of Dietary Supplements says most botanicals lack evidence of their safety and efficacy, and caution is warranted in pregnancy. Added vitamins: if the powder is fortified, count its preformed vitamin A with your prenatal; the NIH Office of Dietary Supplements says experts advise people who are or might be pregnant, and those who are lactating, not to take high doses: more than 3,000 mcg RAE (10,000 IU) a day.

Sources: American College of Obstetricians and Gynecologists (ACOG): Healthy Eating During Pregnancy; Protein and Amino Acid Requirements during Pregnancy (Elango & Ball, Advances in Nutrition, 2016); Consumer Reports: Protein Powders and Shakes Contain High Levels of Lead (2025); American College of Obstetricians and Gynecologists (ACOG): Moderate Caffeine Consumption During Pregnancy, Committee Opinion No. 462; NIH Office of Dietary Supplements: Dietary Supplements for Pregnancy, Fact Sheet for Health Professionals; NIH Office of Dietary Supplements: Vitamin A and Carotenoids, Fact Sheet for Health Professionals

Does protein powder make you gassy?

It can, and the usual culprits are lactose, sugar alcohols and added fiber rather than the protein itself. Whey concentrate contains some lactose, and people with lactose intolerance can get gas, bloating or diarrhea from it. The NIH notes that most of them can handle some lactose (around 12 g, about a cup of milk, causes no or mild symptoms in many), so a smaller scoop may help. Whey isolate is filtered to remove more lactose, and lactase products or a non-dairy powder are other options. Sweeteners ending in "-ol", such as sorbitol and xylitol, can also cause gas, and federal rules require foods likely to supply 50 g of sorbitol a day to warn that "excess consumption may have a laxative effect." Some high-fiber ingredients can cause gas too. Check the ingredient list for these if a powder bothers you, and see a doctor if symptoms are severe or persistent.

Sources: NIDDK (NIH): Eating, Diet, & Nutrition for Lactose Intolerance; NIDDK (NIH): Eating, Diet, & Nutrition for Gas in the Digestive Tract; 21 CFR 184.1835: Sorbitol (laxative-effect labeling)

Are the sweeteners in protein powder safe?

The FDA considers the sweeteners it has authorized safe for the general population under their intended conditions of use. Sucralose, acesulfame potassium and aspartame are approved food additives. High-purity stevia (steviol glycosides) and monk fruit extract are "generally recognized as safe" (GRAS); whole-leaf and crude stevia extracts are not permitted as sweeteners. People with phenylketonuria (PKU) should avoid or restrict aspartame. Sugar alcohols such as erythritol and xylitol are also permitted, though they can cause gas in some people. If you want to avoid a particular sweetener, check the ingredient list.

Sources: U.S. Food & Drug Administration: Aspartame and Other Sweeteners in Food; NIDDK (NIH): Eating, Diet, & Nutrition for Gas in the Digestive Tract

Is expired protein powder safe to use?

Usually, if it has been stored sealed, cool and dry and still looks and smells normal, but it will slowly lose quality. The USDA says that, except for infant formula, the dates on food are about best quality and are not an indicator of safety. In a Journal of Dairy Science study, sealed whey protein concentrates stored at normal room temperature kept for at least 18 months, and bacteria, yeast and mold stayed low throughout; the same powders stored at 35 °C (95 °F) lasted about 9 months. Over time the powders turned yellower, caked, and lost some lysine, an essential amino acid, so old powder may have a little less usable protein than the label says. Throw it out if it is wet, moldy, clumped hard, smells sour or rancid, or tastes off. Keep the lid closed and store the tub away from heat and humidity.

Sources: USDA Food Safety and Inspection Service: Food Product Dating; Storage stability of whey protein concentrates WPC34 and WPC80 for up to 18 months (Tunick et al., J Dairy Sci, 2016)

Does whey protein cause acne?

It might in some people, but the evidence is weak and mixed. Case reports describe young men who developed acne, often on the chest and back, after starting whey supplements, with improvement after they stopped. A proposed reason is that dairy proteins raise insulin and IGF-1, hormones linked to acne. The American Academy of Dermatology says some studies link cow's milk to breakouts, but more research is needed. The only randomized controlled trial so far (49 men with existing acne, 6 months) found 30 g of whey a day was no worse for acne than a non-whey supplement. If you think whey is causing breakouts, try a few weeks on a non-dairy protein such as pea, rice or egg, and see a dermatologist for persistent or severe acne.

Sources: Acne and whey protein supplementation among bodybuilders (Simonart, Dermatology, 2012); Acne located on the trunk, whey protein supplementation: is there any association? (Cengiz et al., Health Promot Perspect, 2017); Whey protein and male acne: a double-blind, randomized controlled trial (Sompochpruetikul et al., J Dermatol, 2024); American Academy of Dermatology: Can the right diet get rid of acne?

Does protein powder hurt your kidneys?

Not in healthy people, according to the best available evidence. A 2018 meta-analysis of 28 studies (1,358 adults without kidney disease) found that higher-protein diets, at 1.5 g/kg a day or more, did not change kidney function over time compared with normal or lower-protein diets. Glomerular filtration rate (GFR) was somewhat higher on high-protein diets, which reflects the kidneys working harder and is not a sign of damage. People with chronic kidney disease are different: the NIH says they may need to eat less protein, because too much can make damaged kidneys work harder, and a dietitian should set the amount. If you have kidney disease, diabetes or high blood pressure, ask your doctor before adding protein powder. Protein from powder counts the same as protein from food.

Sources: Changes in kidney function do not differ between healthy adults consuming higher- compared with lower- or normal-protein diets: systematic review and meta-analysis (Devries et al., J Nutr, 2018); NIDDK (NIH): Eating Right for Chronic Kidney Disease; NIDDK (NIH): Protein Tips for People with Chronic Kidney Disease

Can I take whey protein if I'm lactose intolerant?

Many lactose-intolerant people can take whey isolate, because most of the lactose is filtered out. According to the U.S. Dairy Export Council, whey isolate is at least 90% protein and typically 0.5–1% lactose, which is roughly 0.15–0.3 g in a 30 g scoop. Whey concentrate keeps more lactose. The NIH notes that many people with lactose intolerance can handle around 12 g of lactose (about a cup of milk) with mild or no symptoms, though tolerance varies. Start with a small serving of an isolate, take it with food, or use a lactase supplement. If you still react, the problem may be sweeteners, sugar alcohols or added fiber, or you may need a non-dairy protein such as egg, pea or soy. Whey is still dairy, so it is not safe for anyone with a milk allergy.

Sources: U.S. Dairy Export Council (ThinkUSAdairy): Whey Protein Isolate typical composition; NIDDK (NIH): Eating, Diet, & Nutrition for Lactose Intolerance

Does soy protein lower testosterone or raise estrogen in men?

No, not at normal intakes, according to the clinical evidence. A 2021 meta-analysis of 38 clinical studies found that soy protein and soy isoflavones had no significant effect on total or free testosterone, estradiol, estrone or SHBG in men, regardless of dose or study length. Soy protein isolate, the form used in most soy powders, also keeps far fewer isoflavones than whole soy foods: about 0.5–2 mg per gram of protein, against roughly 3–4 mg in tofu or soymilk, because most are lost in processing. Mark Messina, an author of both papers, has consulted for the soy industry. If you have a hormone-sensitive condition, ask your doctor.

Sources: Reed et al. (2021), Neither soy nor isoflavone intake affects male reproductive hormones: an expanded and updated meta-analysis of clinical studies, Reprod Toxicol; Messina, Barnes & Setchell (2025), Perspective: Isoflavones, intriguing molecules but much remains to be learned about these soybean constituents, Adv Nutr

Does whey protein cause hair loss?

There is no good evidence that it does. A 2026 dermatology literature review found that clinical trials on whey and hair are lacking. The worry rests on indirect theories, mainly that whey raises IGF-1 and might affect androgen pathways, and those have not been shown to cause hair loss in people. Much of what circulates online is anecdote. Check the label: some "mass" or "test-boosting" products add ingredients such as DHEA or other hormone precursors, which is a different question from whey itself. Hair loss has many causes, including genetics, stress, rapid weight loss and low iron or calorie intake, so if you are losing hair, see a dermatologist rather than assuming it is your shake.

Sources: Qasem et al. (2026), The potential impact of whey protein on hair: a literature review of hormonal, metabolic, and nutrient sensing pathways, JAAD Reviews

Can a protein shake keep you awake, or help you sleep?

We found no good evidence that protein powder itself keeps you up or helps you sleep. When a shake does disturb sleep, look first for caffeine: check the label for caffeine, coffee or green tea extract. The FDA notes that caffeine is added to some protein bars and supplements. It lists insomnia among the signs of too much caffeine and says most adults can have up to 400 mg a day without negative effects. Packaged foods must list added caffeine in the ingredients. Caffeine that occurs naturally in an ingredient, such as chocolate, may not be listed separately. Timing can also matter for people with acid reflux: the NIH suggests eating at least 3 hours before lying down if reflux symptoms come on at night.

Sources: FDA: Spilling the Beans: How Much Caffeine Is Too Much?; NIDDK (NIH): Eating, Diet, & Nutrition for GER & GERD

Is whey protein safe for a teenager?

A teenager who eats a balanced diet usually does not need protein powder. The U.S. Recommended Dietary Allowance for ages 14–18 is 52 g of protein a day for boys and 46 g for girls, which regular meals usually cover, even for many athletes. The American Academy of Pediatrics says young athletes who eat a balanced diet do not need protein supplements, and it warns that supplements are not checked by the FDA before sale and are sometimes contaminated. If a teen does use one, treat it as food, not as a shortcut: a plain whey or plant powder with no caffeine, stimulants or other "performance" ingredients, and a third-party certification such as NSF Certified for Sport, which tests for contaminants and banned substances. Talk to a pediatrician first if the teen has a medical condition or is trying to gain or lose weight.

Sources: Institute of Medicine (National Academies): Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, ch. 10 Protein and Amino Acids (2005); American Academy of Pediatrics, HealthyChildren.org: Performance-Enhancing Sports Supplements: Information for Parents; NSF Certified for Sport

What is the best way to compare protein powder prices, and which is cheapest per gram of protein?

Compare the cost per gram of protein, not the price of the tub. Tubs differ in size, scoop size and protein per scoop, so a cheaper tub can cost more per gram. Work it out as: price ÷ (servings × grams of protein per serving). For example, a $60 tub with 30 servings of 25 g of protein is $60 ÷ 750 g = $0.08 per gram, or $2.00 per 25 g of protein. Use the servings and protein grams from the Supplement Facts panel, not the front of the tub. This site lists the cost per 25 g of protein for every product where it can be calculated, and you can sort all powders by that number. Prices change often, so check the current price before you buy.

Why is protein powder so expensive now?

Mainly because whey, the most common protein powder ingredient, is in short supply while demand keeps rising. Food makers are adding whey to yogurts, bars, cereals and drinks, and people on GLP-1 weight-loss drugs such as Wegovy and Zepbound are often told to eat more protein to keep muscle, which adds to demand. Whey is a by-product of cheesemaking, so supply is tied to dairy output and to the specialized plants that filter and dry it, and those take years to expand. The USDA has pointed to tighter whey supplies and higher price forecasts. Dairy processors in the U.S. and Ireland are adding capacity, which could ease the shortage within one to two years, but prices may stay high until then. Brands respond by raising prices, shrinking tubs or reformulating, which is another reason to compare cost per gram of protein rather than price per tub.

Sources: EatingWell: Whey Protein Powder Prices Are Rising, Here's Why (June 2026)

How do I get a smooth protein shake without a blender, and is a clumpy shake OK?

Put the liquid in first, then the powder, and shake hard in a shaker bottle with a wire whisk ball or mixing grid. Powder poured in first sticks to the bottom and forms clumps. Very cold liquid makes some powders harder to dissolve, so mix with cool or room-temperature liquid and add ice afterwards. Letting the shake sit for a minute and then shaking again breaks up what is left. Isolates and clear whey usually mix more easily than concentrates, plant blends or powders with added thickeners. A clumpy shake has the same protein as a smooth one; the lumps are just undissolved powder. If the dry powder in the tub has hardened into lumps, smells off or is past its best-by date, don't use it.

How do I find a protein powder without artificial sweeteners?

Read the ingredient list, not the front of the tub. The common artificial sweeteners in protein powder are sucralose, acesulfame potassium (Ace-K) and aspartame. If you want to avoid them, look for unflavored powders, which usually have no sweetener, or flavored ones sweetened with stevia (often listed as steviol glycosides or Reb A) or monk fruit (luo han guo extract). Some also use sugar alcohols such as erythritol or xylitol, which are not artificial sweeteners but can cause gas in some people. "Naturally sweetened" on the front is a marketing claim, so confirm it against the ingredients. Unflavored powder can be flavored at home with fruit, cocoa or a sweetener of your choice.

Sources: U.S. Food & Drug Administration: Aspartame and Other Sweeteners in Food; NIDDK (NIH): Eating, Diet, & Nutrition for Gas in the Digestive Tract

Does heat destroy protein? Can I put protein powder in coffee or bake with it?

No, heat does not destroy the protein's nutritional value; you can add it to hot coffee or bake with it. Heat denatures protein, meaning it unfolds the molecule, but the amino acids your body uses are still there. A systematic review of milk proteins found denaturation does not affect overall digestibility and can even speed up digestion of whey in the stomach. In a human study, cooked egg protein was about 91% digested versus about 51% for raw egg. Very intense or prolonged heating, especially with sugars (browning), can reduce the availability of some amino acids, mainly lysine. In practice, the bigger issue with hot drinks is texture: whey can clump in very hot liquid, so stir it into a little cool liquid first, or let the coffee cool slightly before you mix it in.

Sources: How processing may affect milk protein digestion and overall physiological outcomes: a systematic review (van Lieshout et al., Crit Rev Food Sci Nutr, 2020); Digestibility of cooked and raw egg protein in humans as assessed by stable isotope techniques (Evenepoel et al., J Nutr, 1998)

Should I mix protein powder with milk or water?

Either works; it depends on your goal. Milk adds about 8 g of protein per cup, whatever its fat level, plus the calories, fat and lactose that come with it, and it makes a thicker, creamier shake. Water adds nothing, so the shake has only what is on the powder label. That suits a calorie deficit, or anyone who is lactose intolerant. For weight gain or a meal replacement, milk is an easy way to add protein and calories.

Sources: U.S. Dairy: How Much Protein Is in Milk?; NIDDK (NIH): Eating, Diet, & Nutrition for Lactose Intolerance

Can I mix a protein shake the night before?

Yes, as long as you keep it cold. A shake made with milk is a perishable food, so treat it like milk. The FDA says to keep the refrigerator at or below 40°F (4°C), and not to leave perishable food out for more than 2 hours (1 hour above 90°F). Mix it, cap it, put it straight in the fridge and drink it the next day. Do not leave it in a gym bag overnight. Expect it to thicken or settle, especially if the powder has gums or added fiber, so shake it again before drinking. Keeping the powder and liquid separate until you drink is the safest option for a long day out of the fridge.

Sources: FDA: Are You Storing Food Safely?