How to choose a protein powder: whey isolate vs concentrate vs plant, and how much protein you really need

Short answer

Most men who lift need about 1.6 g of protein per kg of body weight a day, and a protein powder is simply a convenient way to get part of it. In a meta-analysis of 49 randomized trials with 1,863 people, protein supplements added to strength training increased muscle size and strength, with benefits levelling off at about 1.6 g per kg a day (1). The International Society of Sports Nutrition recommends 1.4–2.0 g per kg a day, in doses of about 20–40 g spread every 3–4 hours (2).

Which powder?

• Whey concentrate — cheapest, good for most people; contains some lactose and fat.

• Whey isolate — more protein per scoop and very little lactose; worth it if dairy upsets your stomach.

• Plant protein (soy, pea, blends) — works as well as whey for muscle when you get enough: in a 12-week trial, men eating a vegan diet with soy protein gained the same muscle and strength as omnivores on whey (3).

One thing to check: a 2025 Consumer Reports test found that more than two-thirds of 23 protein products had more lead per serving than its experts consider safe for a whole day, with plant-based powders averaging about nine times the lead of dairy ones (4).

If you've been training hard and not seeing results, you're not imagining it and it's not a lack of effort — often it's simply not enough protein, sleep or time.

Note: this article is for general education and is not medical advice. If you have kidney disease, liver disease or a milk allergy, talk to a doctor or dietitian before increasing protein or using protein powders. This guide is published by Welltory, which makes one of the apps mentioned. Welltory is a general wellness product: it helps you track and understand your data and does not diagnose or treat any condition.

Do you even need protein powder?

Not necessarily. Protein powder is food, not a supplement with special powers. The ISSN notes that whole foods can meet daily protein needs, and supplements are a practical way to ensure quality and quantity (2). The meta-analysis behind the 1.6 g figure found no difference between protein sources — whey or steak — or between taking it with meals or right after training (1).

A powder makes sense when:

• you struggle to reach your daily target with food;

• you need a quick option after training or between meetings;

• you eat little meat, fish, eggs or dairy;

• you're in a calorie deficit and want more protein per calorie.

How much protein do you need to build muscle?

Two practical points:

• Older men may need more. The meta-analysis found that the benefit of protein supplements declined with age, suggesting older adults may need more protein for the same result (1).

• More training experience, bigger effect. Benefits increased with resistance-training experience (1).

How much protein per meal, and when?

• Per meal: about 0.25 g per kg body weight, or 20–40 g of high-quality protein (2).

• Spacing: spread protein evenly across the day, every 3–4 hours (2).

• Leucine: each dose ideally contains 700–3,000 mg of leucine, the amino acid that switches on muscle building (2). A 25–30 g scoop of whey usually provides this.

• The "anabolic window" is wide. The effect of a workout on muscle building lasts at least 24 hours, so you don't need to sprint to a shake the minute you finish (2).

• Before bed: 30–40 g of casein (the slow-digesting milk protein) before sleep may increase overnight muscle building (2).

Whey isolate vs concentrate: what's the difference?

Both come from milk. The difference is how much they're filtered.

For building muscle, both work well when total daily protein is adequate. If concentrate gives you gas or bloating, try isolate before giving up on whey.

Hydrolysed whey is pre-digested for faster absorption. It costs more and there's little evidence that it builds more muscle for most people.

Whey vs plant protein: which is better for muscle?

When you get enough of it, plant protein works as well as whey.

In a 2021 trial, 38 young men — 19 vegans and 19 omnivores — did supervised weight training twice a week for three months, all aiming for 1.6 g of protein per kg a day. The vegans took soy protein isolate and the omnivores took whey. Both groups gained leg muscle and leg-press strength, with no differences between them (3). The vegans needed more supplemental protein to reach the same target (about 58 g a day of soy vs about 41 g of whey).

Plant proteins tend to have less leucine and lower digestibility, so:

• use a slightly bigger serving;

• choose soy or a blend (pea + rice) rather than a single, less complete source;

• check the lead content, because plant powders tended to have more in testing (4).

Protein powders and heavy metals

In 2025, Consumer Reports tested 23 protein powders and ready-to-drink shakes. More than two-thirds had more lead in a single serving than CR's experts consider safe for a whole day (a threshold of 0.5 micrograms, based on California's Proposition 65). Plant-based powders averaged about nine times the lead of dairy-based ones; whey and dairy products generally had the lowest levels. CR rated seven products as better for daily use. The industry group Council for Responsible Nutrition argued that CR's threshold is self-imposed and not a government safety limit (4).

What that means in practice:

• Don't panic, but don't treat protein powder as harmless filler.

• Prefer dairy-based powders if you can tolerate them.

• Choose products with independent third-party testing.

• Avoid products with a Proposition 65 warning.

• Use one serving a day rather than several, and get the rest of your protein from food.

How to choose a protein powder: a checklist

1. Protein per serving: aim for 20–30 g per scoop.

2. Ingredient list: short is better. Watch for "proprietary blends" and added fillers.

3. Third-party testing: look for an independent testing seal, especially if you're a tested athlete.

4. Sugar: a few grams is fine; some "mass gainers" are mostly sugar.

5. Sweeteners and sugar alcohols: can cause gas and bloating in some people.

6. Lactose tolerance: isolate or plant protein if concentrate upsets you.

7. Price per 25 g of protein: compare this, not price per tub.

8. Taste you'll actually drink: the best powder is the one you'll use.

Protein for men over 40: does the number change?

Yes, a little. Muscle in older adults responds less to the same dose of protein — researchers call this "anabolic resistance." In practice, that means two things.

First, the per-meal dose matters more. A younger lifter may get most of the muscle-building signal from about 20–25 g of protein in a meal. Studies in older men suggest it takes closer to 30–40 g, or roughly 0.4 g per kg of body weight per meal, to get a similar response (1, 2). Spreading a day's protein across three or four real meals usually works better than one big dinner.

Second, leucine — the amino acid that switches on muscle protein synthesis — becomes a useful check. Whey is naturally rich in it (about 2.5–3 g per 25 g serving). Plant blends can match it, but usually need a slightly larger scoop.

None of this means you need more powder. It means that if breakfast is coffee and a croissant, a shake or Greek yogurt there does more work than one at bedtime.

Common protein powder mistakes

Most problems with protein powder are not about the brand. They are about how it fits into the rest of the day.

• Counting the shake but not the meals. Many men already eat 1.2–1.4 g/kg from food. Adding two scoops pushes them well past what research shows helps — the extra just becomes calories.

• Treating it as a meal replacement. A 120-calorie shake is not lunch. If you skip food and drink protein instead, total calories drop and so does training quality.

• Buying "proprietary blends." If the label hides how much of each protein is inside, you cannot tell whether you are paying for whey or for cheap fillers. Look for a single protein grams number per serving.

• Ignoring the scoop size. Two products can both say "25 g protein" — one per 30 g scoop, one per 45 g scoop. The second has more sugar, fillers or flavoring.

• Using it to "fix" poor sleep or recovery. No amount of protein makes up for five hours of sleep. If recovery feels stuck, look at sleep and training load first.

• Expecting a visible change in two weeks. Muscle builds slowly. Weight can move in days from water and food in the gut; muscle takes months.

Mass gainers vs protein powder

A mass gainer is a protein powder with a lot of carbohydrate and sometimes fat added — often 600–1,200 calories per serving. It solves a different problem.

• Calories per serving — Protein powder: 100–150; Mass gainer: 600–1,200

• Protein per serving — Protein powder: 20–30 g; Mass gainer: 30–60 g

• Carbohydrate — Protein powder: 1–5 g; Mass gainer: 80–250 g

• Who it suits — Protein powder: Most people topping up protein; Mass gainer: People who truly cannot eat enough calories

• Main risk — Protein powder: Paying for protein you do not need; Mass gainer: Gaining fat, not muscle; bloating

If you are a "hardgainer" who struggles to eat, a homemade shake — milk, oats, banana, peanut butter and a scoop of whey — usually gives you the same calories with better ingredients and a lower price. Buy a gainer only if convenience is the main barrier.

How to tell if your protein intake is working

You cannot feel muscle protein synthesis. You can watch for signs that the whole plan — training, food, sleep — is moving the right way.

1. Strength trend. Log your main lifts. If the weight or reps on two or three key exercises go up over 6–8 weeks, you are building something.

2. Body weight and waist. For a lean bulk, weight creeping up about 0.25–0.5% per week while the waist stays the same is a good sign.

3. Soreness and readiness. If you are constantly wrecked two days after training, the issue is more often total load and sleep than protein.

4. Resting heart rate and HRV. These do not measure protein. They do show whether your body is coping with the training load. A resting heart rate that drifts up and HRV that stays below your usual range for several days often mean you are under-recovered.

5. Photos and measurements every 4 weeks. The mirror lies day to day. Monthly photos in the same light do not.

If strength and measurements stall for more than 8 weeks while protein is at 1.6 g/kg, the fix is usually in the program — progressive overload, sleep, total calories — not in a different powder.

Protein powder vs food: what's the difference?

Protein powder isn't more effective than food protein — it's more convenient. Food brings fibre, vitamins and minerals that powders don't. A practical day for an 80 kg man aiming for about 130 g might look like:

• breakfast: Greek yogurt with nuts and fruit (~25 g);

• lunch: chicken or beans with rice and vegetables (~35 g);

• post-training: one protein shake (~25 g);

• dinner: fish or tofu with potatoes and salad (~35 g);

• snack: eggs, cottage cheese or a glass of milk (~15 g).

If you hit your target with food most days, a powder adds little.

When will you see results from protein and training?

Protein doesn't build muscle by itself — training does, and protein supplies the material. Realistic expectations for a man starting a structured strength program:

• Weeks 1–4: strength rises first, largely because your nervous system learns the movements.

• Weeks 6–12: visible muscle growth starts to show, especially in beginners.

• Months 3–6 and beyond: steady but slower gains; more experienced lifters gain less per month.

The 49-trial meta-analysis only included studies lasting at least six weeks, and found the extra benefit of protein supplements was real but smaller than supplement marketing suggests (1). Our guide on how long it takes to see results from training, creatine and protein goes into detail.

Is a lot of protein bad for your kidneys?

For healthy people, higher protein intakes of the kind used by athletes haven't been shown to harm the kidneys. If you have chronic kidney disease, though, high protein can be harmful, and your doctor or dietitian may advise a lower intake. Get your kidney function checked before going high-protein if you have diabetes, high blood pressure or a family history of kidney disease.

Living with a training plan: the questions people ask next

Should I take protein before or after a workout?

Either is fine. The effect of training on muscle building lasts at least 24 hours, and the meta-analysis found no difference between protein taken with meals or after training. Hitting your daily total matters most.

Can I take protein powder and creatine together?

Yes. Mixing creatine into a protein shake is convenient and may help creatine retention. See when to take creatine.

Is casein better than whey?

Not overall. Casein digests slowly, which makes it a good choice before bed; whey digests quickly, which is convenient after training. Both build muscle.

Do I need protein on rest days?

Yes. Muscle building continues for a day or more after training, and your daily protein target applies every day.

Before you blame yourself

If your physique hasn't changed much after a couple of months, it's not proof you're doing it wrong. Muscle grows slowly, sleep and stress matter as much as the gym, and many men simply undershoot their protein. Track it for a week before changing everything else.

When to see a doctor

See a doctor or dietitian before a high-protein plan if you have kidney disease, liver disease, gout, diabetes or a family history of kidney problems; if dairy causes hives, swelling or breathing problems (possible milk allergy); or if you have persistent digestive symptoms with protein powders.

How to bring this up with your doctor

What to ask for, by name. "Is a protein intake of about [number] g a day safe for me, given my kidney function?"

What to bring. Your weight, a typical day of eating, the protein powder label, and recent blood test results.

What to say, out loud. "I'm strength training [N] times a week and aiming for [number] g of protein a day. Is that appropriate for me?"

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How Welltory helps — and what it cannot do

The limits first. Welltory is a general wellness product, not a medical device. It doesn't count protein or measure muscle.

What it can do is show whether you're recovering from the training your nutrition is supposed to support.

Recovery readings. Take a morning HRV measurement with your phone camera, a compatible watch or a chest strap (camera measurements, accurate HRV measurements).

Tag what you change. Tag "new protein powder", "upper body day", "high-protein day", "poor sleep" when Welltory asks "What happened?" (My Patterns). Patterns start to appear after around seven tagged events; some sections need a paid plan.

A record for your doctor or coach. From the web app you can export your data as CSV (export guide).

How we made it

We based this article on a 2018 meta-analysis of 49 randomized trials of protein supplementation and resistance training, the International Society of Sports Nutrition's 2017 position stand on protein and exercise, a 2021 randomized trial comparing soy and whey in vegan and omnivorous men, and Consumer Reports' 2025 test of lead in protein powders. Search questions came from what people in the United States most often ask about protein powders. For the product section, we checked every function against the Welltory Help Center on October 23, 2026.

Made with AI tools, then edited and fact-checked by the Welltory team. See our Editorial & AI policy.

Jane Smorodnikova, co-founder of Welltory, built the methodology behind how we read physiological data.

Written by Tatsiana Yashyna.

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