Whey Protein Guide — Types, Dosage and Is It Worth It?
Whey protein is the most popular supplement in fitness, and also one of the most misunderstood. It is not a magic muscle-builder, it is not a meal replacement, and it is not necessary — but it is convenient, cheap per gram of protein, and supported by good evidence as a way to reach a protein target that is otherwise hard to hit.
This guide covers the three types of whey, how much you actually need, when to take it, and whether it is worth the money. The headline is simple: whey is food in powdered form, and its only job is to make hitting your protein target easier. If you already hit your target from food, it adds nothing; if you do not, it is the easiest fix available.
Use the calculator
Start with the numbers: try our protein calculator to work out your own figures before applying anything on this page. The worked examples below use round numbers so you can follow the maths; the calculator uses your real weight, height, age and goal.
Related reading: protein calculator, macro calculator, Supplements Worth Taking, Supplements to Avoid, full guides section.
The formula behind whey protein
The numbers that matter are the protein targets, not the supplement. The evidence-based range for people who lift is 1.6–2.2 g/kg/day (Morton et al., 2018, British Journal of Sports Medicine), with a 2016 meta-analysis finding that 1.6 g/kg/day maximised muscle gain and higher intakes giving no additional benefit for most people. A typical whey serving is 25 g of powder containing about 20–25 g of protein, 1–2 g of fat and 1–3 g of carbohydrate, at roughly 100–120 kcal — so for an 80 kg lifter needing 128–176 g a day, one scoop covers about a sixth of the target. The per-meal dose also matters: muscle protein synthesis is maximally stimulated by about 0.25 g/kg per meal (roughly 20 g for an 80 kg person), with a ceiling around 0.4 g/kg per meal, according to the research summarised by Schoenfeld and Aragon (2018). And the calorie maths uses the Mifflin-St Jeor equation (Mifflin et al., American Journal of Clinical Nutrition, 1990) — 10 × weight (kg) + 6.25 × height (cm) − 5 × age, plus 5 for men or minus 161 for women, times an activity factor — to set total calories, because whey is a small part of a total diet, not a diet on its own. The safety floors (1,200 kcal/day women, 1,500 kcal/day men) apply to the whole diet, not to the supplement.
The key points
Whey is food, not a drug. Whey is the liquid left over from cheese-making, filtered and dried into a powder. It is a complete protein — it contains all nine essential amino acids — and it is rich in leucine, the amino acid that most strongly triggers muscle protein synthesis. It is digested quickly, which makes it convenient after training, but it is not fundamentally different from the protein in milk, eggs or meat. The supplement industry markets it as a muscle-builder; the honest description is 'convenient protein'.
Concentrate, isolate and hydrolysate — the real differences. Whey concentrate is about 70–80% protein, with some lactose and fat left in; it is the cheapest and the best value for most people. Whey isolate is filtered further to about 90% protein, with almost no lactose or fat — better if you are lactose-intolerant or counting calories tightly, but more expensive per gram of protein. Whey hydrolysate is pre-digested (the protein chains are broken into smaller pieces), which makes it absorb faster and taste worse, at the highest price — and the evidence that the faster absorption matters is weak. For most people, concentrate is the right choice; isolate if lactose is a problem; hydrolysate rarely worth the premium.
Timing matters far less than the total. The 'anabolic window' — the idea that you must drink a shake within 30 minutes of training — is exaggerated. A 2013 meta-analysis in the Journal of the International Society of Sports Nutrition found total daily protein intake mattered far more than timing, and the effective window is roughly 4–6 hours around training. If you ate protein a couple of hours before training, there is no urgency at all. Take whey when it is convenient — after training, at breakfast, or as a snack — and focus on the daily total.
How much do you actually need? The target is 1.6–2.2 g/kg/day for lifters, and whey's job is to fill the gap between what food provides and that target. If you eat 100 g of protein from food and need 140 g, one scoop of whey closes the gap. If you already eat 140 g from food, whey adds nothing — and extra protein beyond about 1.6 g/kg/day gives no additional muscle gain for most people. Work out the gap first, then decide whether a supplement is needed at all. And the kidney caveat: if you have kidney disease, protein targets change completely — discuss them with a clinician.
Side effects are usually about lactose. The commonest side effects of whey are digestive: bloating, gas and stomach discomfort, usually from the lactose in concentrate. Switching to isolate (almost lactose-free) or to a plant protein usually fixes it. Whey is not harmful to healthy kidneys — that claim comes from confusing the protein needs of people with existing kidney disease with the effects of protein on healthy kidneys, and the evidence does not support it for healthy adults. If you have kidney disease, though, the rules are different and a clinician should set your protein target.
Is it worth the money? Whey is one of the cheapest sources of protein per gram — usually cheaper than meat or fish, and comparable to eggs and milk. A tub that costs £30–40 and contains 30 servings works out at about £1–1.30 per serving for 25 g of protein, which is good value. But it is only worth it if you need it: if you already hit your protein target from food, the money is better spent on food. And check the label — some products are mostly carbohydrate and flavouring with little protein, and the cheapest per tub is not always the cheapest per gram of protein.
At a glance
| Type | Protein per 25 g scoop | Lactose | Fat | Cost per gram of protein | Best for |
|---|---|---|---|---|---|
| Concentrate | ~20 g | Some (3–4 g) | ~1–2 g | Lowest | Most people |
| Isolate | ~22–23 g | Almost none | ~0.5 g | Medium | Lactose-intolerant, tight calories |
| Hydrolysate | ~22 g | Almost none | ~0.5 g | Highest | Rarely worth the premium |
| Plant blend (pea + rice) | ~20 g | None | ~1–2 g | Medium | Dairy-free, vegan |
| Casein | ~20 g | Some | ~1 g | Medium | Slow digestion, before bed |
| Food: 2 eggs | ~12 g | None | ~10 g | Low | Whole-food alternative |
| Food: 150 g Greek yoghurt | ~15 g | Some | ~0–5 g | Low | Whole-food alternative |
A worked example: does this lifter need whey?
Take a 30-year-old man, 80 kg, 180 cm, who lifts three times a week and eats three meals a day: breakfast (eggs and toast, about 20 g protein), lunch (chicken sandwich, about 35 g), dinner (beef and rice, about 40 g), plus snacks (about 15 g). His total is about 110 g a day. His BMR by Mifflin-St Jeor is 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 800 + 1,125 − 150 + 5 = 1,780 kcal/day, and at moderately active (× 1.55) his maintenance is about 2,759 kcal/day. His protein target at 1.6–2.2 g/kg is 128–176 g per day, so he is 18–66 g short — a gap that one scoop of whey (about 25 g of protein, 120 kcal) closes almost exactly if he aims for the lower end of the range, or two scoops if he aims for the upper end. The cost: about £1–1.30 a day for one scoop, or about £30–40 a month. The alternative is food: an extra chicken breast (about 30 g protein) or 200 g of Greek yoghurt (about 20 g) would do the same job for a similar price. The honest conclusion: whey is worth it for him if he finds the shake more convenient than the extra food, and not worth it if he would rather eat. The protein is the same; only the delivery changes.
How to use this guide
Work out your protein target first with the protein calculator (1.6–2.2 g/kg/day if you lift), then add up the protein you actually eat on a typical day. If the gap is less than 20 g, fix it with food. If the gap is 20 g or more, a scoop of whey is the easiest fix — one scoop a day, taken whenever it is convenient, mixed with water or milk. Choose concentrate unless you are lactose-intolerant (then isolate) or dairy-free (then a pea-and-rice blend). Check the label for protein per serving and cost per gram of protein, not just the price per tub. And re-check the gap every few months: as your diet changes, the need for a supplement may disappear, and the money is better spent on food when it does.
What this guide does NOT tell you
Whey protein is a food supplement, not a medicine, and this guide does not diagnose or prescribe anything. The protein ranges (1.6–2.2 g/kg/day) assume a generally healthy adult who lifts weights — they do not apply to people with kidney disease, for whom protein targets are set by a clinician, or to children and teenagers, for whom supplements are generally not recommended. The evidence for whey's benefits is good for reaching a protein target, but whey does not build muscle on its own — without resistance training and enough total calories, extra protein is simply oxidised for energy. Supplement quality varies: protein powders are not regulated as strictly as medicines in many countries, so choose products from reputable brands with third-party testing where available. And the safety floors apply to the whole diet: never go below 1,200 kcal/day for women or 1,500 kcal/day for men without medical supervision, whatever supplements you take.
Frequently asked questions
Do I need whey protein to build muscle?
No — you need enough total protein (1.6–2.2 g/kg/day) and resistance training. Whey is just a convenient way to reach the protein target. If you already hit your target from food, whey adds nothing. If you do not, one scoop a day is the easiest fix — but food works just as well.
What is the difference between whey concentrate and isolate?
Concentrate is about 70–80% protein with some lactose and fat, and it is the cheapest. Isolate is filtered further to about 90% protein with almost no lactose or fat, so it is better if you are lactose-intolerant or counting calories tightly, but more expensive per gram of protein. For most people, concentrate is the right choice.
When should I take whey protein?
Whenever it is convenient. The '30-minute anabolic window' is exaggerated — a 2013 meta-analysis found total daily protein intake mattered far more than timing, and the effective window is roughly 4–6 hours around training. After training, at breakfast, or as a snack all work. Focus on the daily total, not the clock.
Is whey protein bad for your kidneys?
Not for healthy adults — that claim confuses the protein needs of people with existing kidney disease with the effects of protein on healthy kidneys, and the evidence does not support it for healthy people. If you have kidney disease, though, protein targets are set by a clinician, and this guide's ranges do not apply to you.
How much whey protein should I take per day?
Enough to fill the gap between what food provides and your target of 1.6–2.2 g/kg/day. For most people that is one scoop (about 25 g of protein) a day, sometimes two. More than that is rarely useful — beyond about 1.6 g/kg/day, extra protein gives no additional muscle gain for most people.
Is whey protein worth the money?
Usually, yes — if you need it. It is one of the cheapest sources of protein per gram, at about £1–1.30 per serving. But it is only worth it if there is a gap to fill: if you already hit your protein target from food, spend the money on food instead. Check cost per gram of protein, not just price per tub.
Estimates only, not medical advice. Minimum safe intakes: 1,200 kcal/day women, 1,500 kcal/day men — consult a healthcare professional before a very-low-calorie diet.