How to Choose a Protein Powder

By the Strength from the Well Editorial Team · Evidence last reviewed September 2026 · Not reviewed by a licensed clinician (why we say that)

The short answer

Choosing a protein powder comes down to five checks you can do in about two minutes: how many grams of protein are in a serving compared to the size of that serving, what the cost works out to per gram of protein, whether the protein source fits your body and your diet, what the added sweeteners and gums are, and whether an independent organization has tested the product. Concentrate, isolate and hydrolysate are processing levels, not quality grades, and the most expensive tub on the shelf is frequently not the best value.

Key points

Compare grams of protein per serving against grams per scoop. That ratio exposes filler faster than any other number.
Cost per gram of protein, not price per tub, is the honest comparison. Divide total price by (servings x grams of protein).
Isolate is more filtered than concentrate, which means less lactose, fat and carbohydrate, not a better protein.
For plant proteins in particular, third-party testing matters because plants concentrate heavy metals from soil.
Digestive complaints usually come from lactose, added gums or sugar alcohols rather than from the protein itself.
Amino spiking is rare in reputable brands but is worth watching for when a cheap product claims premium protein numbers.

Start by asking what the powder is for

Protein powder solves a logistics problem, not a biological one. It is a fast, portable, shelf-stable way to get 20 to 30 grams of protein when cooking is not realistic. That is genuinely useful for someone lifting seriously, someone recovering from surgery or illness, an older adult whose appetite has dropped, or anyone whose schedule keeps eating a real meal from happening.

It is not a requirement for health, and it does not do anything that chicken, eggs, lentils or fish do not also do. Knowing that keeps you from overpaying for a tub that promises more than a food can deliver. If you already hit your protein target with meals, a powder is a convenience purchase, and you should shop for it the way you would shop for any convenience.

The five checks

First, protein density. Find grams of protein per serving, then find the serving size in grams, usually printed right next to the scoop count. A powder giving 25 grams of protein in a 30 gram scoop is about 83 percent protein. One giving 21 grams in a 42 gram scoop is 50 percent protein, and the other half is carbohydrate, fat, fiber, flavoring and thickener. Neither is wrong, but you should know which you are buying.

Second, cost per gram of protein. Multiply servings per container by grams of protein per serving to get total grams in the tub, then divide the price by that number. Do this for two or three candidates and the ranking often flips from what the shelf price suggested. Large tubs of a plain flavor are usually the cheapest per gram.

Third, the source. Whey and casein come from milk and are off the table for a milk allergy. Soy and egg are complete but are themselves common allergens. Pea, rice and blends are the standard plant options. Collagen is not a complete protein and should not be your main source. Match the source to your actual restrictions before you look at anything else.

Fourth, what else is in there. Scan the ingredient list and the 'Other ingredients' line for sweeteners, sugar alcohols, gums, and any allergen derivative. This is where most of the 'this protein wrecks my stomach' stories originate.

Fifth, third-party testing. Look for a seal from an independent organization that verifies contents and screens for contaminants. This is the only part of the package that reflects someone outside the company opening the product and checking it.

Grams of protein divided by grams per scoop, expressed as a percentage
Price divided by total grams of protein in the container
Source matched to your allergies and dietary limits
Sweeteners, gums and allergen derivatives in the full ingredient list
An independent testing seal, not just the words 'lab tested'

Concentrate, isolate, hydrolysate: what the words mean

These describe how far the raw protein was filtered and processed, and marketing has turned them into a quality ladder they are not.

Concentrate is the least processed. It typically runs 70 to 80 percent protein by weight and keeps more of the naturally occurring fat, carbohydrate and, for whey, lactose. It tastes richer and costs less.

Isolate is filtered further, generally 90 percent protein or more, with most of the lactose and fat removed. For someone who is lactose intolerant, that difference is the entire point. For someone who is not, isolate is mostly paying more for a smaller scoop.

Hydrolysate has been partially broken down into shorter amino acid chains, which speeds absorption modestly and tastes noticeably worse. For clinical situations involving impaired digestion it can matter. For a healthy person having a shake after the gym, the difference in outcome is small enough that the price premium is hard to justify.

None of these three is a purity grade or a safety grade. A well-made concentrate from a company that tests its product is a better buy than an untested hydrolysate.

Sweeteners, gums and the stomach problem

A large share of complaints about protein powder are not about protein. Whey concentrate carries lactose, which is a problem for the many adults who do not digest it well. Sugar alcohols such as erythritol, maltitol and sorbitol are used to sweeten without sugar and can cause gas, cramping and loose stools in ordinary amounts. Sucralose, stevia, monk fruit and acesulfame potassium are calorie-free sweeteners that most people tolerate, though some report bloating.

Gums and thickeners, most often xanthan gum, guar gum, gellan gum and cellulose gum, exist to keep the powder from separating and to make water feel like milk. They are common and generally fine, but they are fermentable and a sensitive gut can object.

If a powder disagrees with you, the efficient move is not to conclude you cannot tolerate protein. Try an unflavored version of the same source, or a different sweetener system, before you write off the whole category. Many people who thought they had a whey problem actually had a lactose problem or a maltitol problem.

Claims that are not worth paying for

'Grass-fed whey' has a real meaning for the cow and a negligible one for the isolated protein, which is nearly identical either way. 'Cold processed' and 'undenatured' sound protective, but denaturing simply means the protein has unfolded, which also happens in your stomach and during cooking, and it does not reduce the protein's value. 'Pharmaceutical grade' has no regulatory definition for supplements. 'Clinically proven' usually refers to a study on one ingredient, not on the product in the tub.

Added digestive enzyme blends are cheap to include and heavily advertised. If lactose is your issue, a lactase enzyme is genuinely relevant; a generic proteolytic blend in a powder is unlikely to change much for a healthy digestive system.

One claim that is worth something is a specific testing seal naming the organization. Another is full disclosure of every ingredient amount instead of a proprietary blend. Those two cost the company money and effort, which is exactly why they signal more than adjectives do.

Amino spiking, briefly and without alarm

Protein content on a label is commonly determined by measuring nitrogen, and free amino acids such as glycine and taurine, plus creatine, contain nitrogen without contributing complete protein. Adding cheap nitrogen sources to inflate the measured protein number is called amino spiking or nitrogen spiking.

This is not widespread among established brands, and it is not a reason to distrust the whole category. But if a product is priced far below everything comparable and lists free amino acids high in its ingredient list, that combination is worth a second look. A third-party seal largely removes the concern, because those programs verify what the label claims.

Common questions

How much protein do I actually need in a shake?

For most adults, 20 to 30 grams of a complete protein in one sitting covers what the body can readily use for muscle repair at a time. Larger amounts are not wasted in a general sense, since the body uses protein for many purposes, but the extra does not add proportionally more benefit for muscle building.

Is plant protein as good as whey?

For practical purposes, yes, if you use a complete source like soy or a pea and rice blend and you get enough total protein. Whey has a slight edge in leucine content and absorption speed, which matters most at the margins of serious training. For everyone else the gap is small.

Does protein powder expire?

It has a best-by date rather than a hard expiration. Over time protein powder can lose some lysine availability and the flavor degrades, particularly after opening. Keep it sealed, dry and out of heat. If it clumps hard, smells off or changes color, discard it.

Do I need to worry about heavy metals in protein powder?

It is a reasonable concern, especially for plant-based powders, because plants take up trace metals from soil and concentrating the protein concentrates whatever came with it. Independent testing programs screen for heavy metals, which is the simplest way to address it without guessing.

Sources

This is information, not medical advice. Strength from the Well is an independent publisher. Nothing here is a diagnosis, a prescription, or a recommendation to start or stop any treatment. Talk to a clinician who knows your history before you act on anything you read here — including anything you read here that contradicts them.