How to Choose a Protein Powder: Types, Testing and Cost

Protein powder is just a convenient, concentrated food. It doesn’t do anything that chicken, eggs, Greek yogurt or beans can’t, but it can make it much easier to hit a daily protein target, especially if you train hard, eat a plant-based diet, have a small appetite or are older.

With hundreds of products on the shelf, it’s hard to tell which are worth the money. This guide explains the main types of protein powder, how much protein you need, what quality seals mean, the heavy metal issue, and how to compare the real cost. For more buying guides, see our supplement guides.

Do you need protein powder?

Most adults need at least 0.8 grams of protein per kilogram of body weight a day, the US Recommended Dietary Allowance. People who strength train, older adults trying to keep muscle, and people losing weight often benefit from more, typically 1.2 to 1.6 g per kg. For a 70 kg (154 lb) person, that’s roughly 85 to 110 grams a day.

Many people reach that from food. Protein powder is useful if you struggle to, if you want a quick post-workout option, or if you don’t eat meat or dairy. Our protein calculator estimates your personal target.

Types of protein powder compared

Protein content is a typical range by dry weight; check each product’s label.

Whey

Whey comes from milk and is the best-studied protein for building muscle. It’s a complete protein, digests quickly, and is rich in leucine, the amino acid that most strongly switches on muscle building. Whey concentrate is the cheapest. Whey isolate is filtered further, so it’s higher in protein and lower in lactose and fat, which suits most people with mild lactose intolerance.

Casein

Casein is the other main milk protein. It forms a gel in the stomach and releases amino acids slowly over several hours, so it’s popular before bed or as a filling snack. Many “milk protein” powders contain both whey and casein.

Plant proteins

Soy is a complete protein with a long research record. Pea protein is rich in leucine and other branched-chain amino acids but low in methionine, while rice protein is the reverse, which is why pea and rice are often blended. A well-designed plant blend can match whey for muscle building when the serving provides enough leucine, usually by using a slightly larger scoop.

Collagen

Collagen powders are popular for skin, hair and joints, but collagen lacks the essential amino acid tryptophan and is low in leucine. It’s not a good choice if your goal is building or keeping muscle, and grams of collagen shouldn’t count fully toward your protein target.

What the research shows

Each finding below carries an evidence label, explained in our editorial policy.

Muscle and strength with training Strong evidence

Protein supplements add a modest boost to the gains from strength training, mostly by helping people eat more protein overall.

In other words, the powder itself isn’t magic. It helps if it gets you closer to around 1.6 g per kg; beyond that, extra protein adds little for muscle.

Older adults Moderate evidence

Older people need more protein per meal to stimulate muscle building. Protein supplements combined with resistance exercise help preserve muscle and strength, while supplements without exercise show smaller or inconsistent benefits.

Weight loss and fullness Moderate evidence

Higher-protein diets help people feel full and keep more muscle while losing weight. A protein shake can help as a planned snack or meal replacement, but adding shakes on top of your usual diet adds calories.

Recovery and soreness Limited evidence

Protein after exercise supports muscle repair, but studies on whether it reduces soreness or speeds recovery between sessions are mixed.

What to look for on the label

• Protein per serving: aim for 20 to 30 g per scoop (25 to 40 g for older adults or plant proteins). Check the scoop size in grams; a bigger scoop isn’t always more protein.
• Protein as a share of the scoop: divide protein grams by the serving weight. A 30 g scoop with 24 g of protein is 80% protein; one with 20 g is only about 67%, with the rest being carbs, fat or fillers.
• Leucine: some brands list it. About 2 to 3 g per serving is a good target for muscle building.
• Amino acid spiking: some products add cheap amino acids such as glycine or taurine to inflate the protein number. A full amino acid profile or third-party testing helps rule this out.
• Proprietary blends: a “protein matrix” without amounts may hide a cheap protein as the main ingredient.
• Added sugar and calories: many flavored powders and “mass gainers” add a lot of sugar. Unflavored or lightly sweetened powders give you more control.
• Extras: added creatine, caffeine, herbs or “fat burners” make a product harder to judge. Buy them separately if you want them.
• Allergens: check for milk, soy, egg and tree nuts, and look for gluten-free labeling if you need it.

For a step-by-step guide to any Supplement Facts or Nutrition Facts panel, see how to read a supplement label.

Heavy metals and third-party testing

Protein powders can contain traces of lead, cadmium and arsenic, which plants absorb from soil and which can also enter during processing. The FDA doesn’t set enforceable limits for heavy metals in protein powders, and products aren’t tested before they’re sold.

In 2025, Consumer Reports tested 23 protein powders and ready-to-drink shakes. More than two-thirds contained more lead per serving than its experts’ daily level of concern, and plant-based powders averaged about nine times more lead than dairy-based ones. Whey and other dairy products generally had the lowest levels.

Context matters: Consumer Reports uses a very cautious threshold, and most products were considered fine for occasional use. But no amount of lead is known to be safe, and it builds up in the body over time, so daily users should take this seriously.

• Choose dairy-based protein if it suits your diet, as it tends to be lowest in heavy metals.
• If you’re plant-based, choose brands that publish batch test results for lead, cadmium and arsenic, and consider rotating products.
• Look for NSF Certified for Sport or Informed Sport seals, which test for contaminants and banned substances. NSF Certified for Sport also sets limits for heavy metals.
• Don’t rely only on protein powder for your protein. Mix it with whole foods.
• Pregnant and breastfeeding women and children should be especially cautious about daily use of protein powders, particularly plant-based ones.

How to compare the real cost

Price per tub or per scoop is misleading, because tub sizes and protein per scoop vary widely. The fair comparison is cost per gram of protein.

To work it out, multiply the protein per serving by the number of servings to get total protein in the tub, then divide the price by that number. For example, a $45 tub with 30 servings of 25 g has 750 g of protein, or about 6 cents per gram. A $35 tub with 20 servings of 20 g has 400 g of protein, or nearly 9 cents per gram, so the “cheaper” tub is actually more expensive.

Our protein cost calculator does this for you and lets you compare powders with foods such as chicken, eggs, Greek yogurt and lentils.

How to use protein powder

• Spread your protein: eating 20 to 40 g of protein at each meal is more effective for muscle than one very large dose.
• Timing: having protein within a few hours of training is helpful, but your total daily intake matters most.
• Before bed: casein or milk protein before sleep may support overnight muscle repair.
• Beyond shakes: stir it into oatmeal, yogurt, pancakes or baked goods.
• Pair it with training: protein supports muscle growth, but resistance exercise is what drives it. Many people combine it with creatine monohydrate, which has strong evidence for strength.

Side effects and who should be careful

Protein powders are generally safe for healthy adults. The most common issues are digestive: bloating, gas or diarrhea, often from lactose in whey concentrate, from sugar alcohols and sweeteners, or from a sudden jump in protein and fiber.

See also our medical disclaimer.

Protein powder FAQ