If you're interested in protein powder to supplement your workouts or boost wellness, you're not alone. Sports supplements and meal replacements are multibillion-dollar markets. Whether you are a hardcore bodybuilder or an occasional gym-goer, protein is what helps you build muscles. However, the abundant choices available on store shelves and online retailers along with the confusing labels can be a bit overwhelming. We tapped top nutrition experts to help you find the protein powder that best fits your needs.
“The number one goal is to make sure there’s some balance between proteins, healthy carbohydrates and fats.”
Tori Holthaus, MS, RDN, LD and founder of YES! Nutrition
Whey or No Whey?
Cow’s milk contains two main dairy proteins: whey and casein. Whey protein absorbs quickly post workout, so you can access muscle-building amino acids soon after you drink it. It’s also a complete protein, which means it contains all amino acids essential in your diet.
However, it does have drawbacks. Dairy proteins – particularly fast-absorbing ones like whey – trigger an insulin response in your body, says Dr. Barry Sears, Ph.D., bestselling author of "The Zone Diet" and "The Mediterranean Zone." So whey isn’t your ideal choice to stabilize insulin levels. If that's a concern, Dr. Sears recommends egg-white protein as the best option for hormone balance.
Similar to whey, casein protein comes from dairy, but is digested slowly, resulting in a slower, steadier breakdown of amino acids that leaves you feeling satisfied for longer. While this can be advantageous during long stretches of time when you go without food (like before bed), it is not ideal immediately after a workout when you want to get the amino acids into your system quickly.
Straight Talk on Soy
Soy protein has some benefits – it’s a complete protein that’s also vegan-friendly – but both Dr. Sears and Tori Holthaus, an Ohio-based registered dietitian and founder of YES! Nutrition, agree it's not ideal for everyone. Some soy protein powders contain isoflavones, which can prevent thyroid hormone from binding to its receptor – a potential health concern, says Dr. Sears. It might also interact with other hormones, reducing testosterone in men and affecting estrogen activity in women. If you're set on using soy protein, avoid soy protein isolate, and look for alcohol-extracted organic, non-GMO powders.
Consider other plant-based options. Quinoa- and hemp-derived powders offer complete amino-acid profiles without the potential hormone-disrupting effects. Other plant-derived proteins – like brown rice or pea proteins – lack some essential amino acids, but still support muscle growth when paired with a balanced diet.
Learn the Label Lingo
Practice savvy shopping and always check the nutrition label. "Avoid any powder that contains artificial sweeteners, colors or flavors, or partially hydrogenated fats," recommends Holthaus. "Those are all things our bodies don’t know how to process or recognize." Look for natural flavors and sweeteners or unflavored/unsweetened protein powders instead. If you're going with dairy protein, opt for organic whey and casein derived from grass-fed cattle to sidestep potential negative effects. It's not yet clear how dairy protein from rBGH-treated cattle affects your health, says Dr. Sears.
Look for “GMP-certified” or other certifications on the label. The FDA sets current good manufacturing practices – cGMPs – that all supplement manufacturers selling in the U.S. must follow. Third-party agencies grant GMP certification to manufacturing facilities that meet those standards, says a representative from NSF International, which offers GMP certification, so any supplements made in certified facilities are GMP certified. Individual product testing – denoted by a blue NSF certification label – goes a step further, ensuring that the product contents match what's on the label and that the supplement is free of unsafe contaminants, like heavy metals.
The golden rule for protein powder remains the same, regardless of your gender, fitness goals or chosen protein source. “The number one goal is to make sure there’s some balance between proteins, healthy carbohydrates and fats,” says Holthaus. Aim for 20 to 30 grams of protein per shake, and blend with other ingredients for a well-rounded meal.
For weight loss, Holthaus recommends blending 120 to 180 calories’ worth of protein powder with half a banana and a handful of spinach. Body size and composition determine how many calories you need. Women, who tend to be smaller and have less muscle than men, should aim for the lower end of that calorie range. Take protein powder after a muscle-building strength workout, but skip it after a cardio session.
Looking to bulk up? Keep that balance of carbs, protein and fat, but scale up the portion size. The amount of protein and calories you need to bulk depends on factors that vary from person to person – including your current workout regimen, height, muscle mass, body fat percentage and ultimate fitness goals – so consult a registered dietitian for best results.
Regardless of your fitness goal, drink your post-workout shake within an hour of your workout for optimal recovery.
Keeping Your Balance
Protein Powders at a Glance
Whey - derived from dairy - fast-absorbing, complete protein - ideal immediately post workout - choose organic, grass-fed
Casein - derived from dairy (sometimes called “milk protein”) - slow-absorbing, complete protein - satisfying and filling - ideal before bedtime or long stretches between meals - choose organic, grass-fed
Egg White - easily-digested complete protein - cholesterol-free - non-dairy/lactose-free - best option for hormone balance
Soy - complete protein - non-dairy - not ideal due to effects on hormones
Brown Rice/Pea - vegan, non-dairy, soy-free, gluten-free - low in certain amino acids (lysine for brown rice, cysteine and methionine for pea) - good to pair with each other or with protein-rich foods
Hemp/Quinoa - complete protein - vegan, non-dairy, soy-free, gluten-free - high in omega-3 and omega-6 fatty acids - some varieties are high in fiber, which supports weight loss