How much protein do you really need? For muscle gain and on a diet

How much protein do you need to build muscle?

2.0 g per kilo of body weight a day. A large meta-analysis of 49 studies with over 1,800 participants found no additional muscle gain beyond about 1.6 g per kilo. Because the statistical uncertainty reached up to 2.2 g, the authors recommend aiming closer to that to be on the safe side (Morton et al., 2018). 2.0 g is above the 1.6 g estimate and within that uncertainty.

In practice, that means: below 1.6 g you're probably leaving something on the table. Going well above 2.2 g brings hardly any extra benefit when you're building muscle, but it takes up room in your calorie budget that is then missing for the carbs that fuel your training. That's why the calorie calculator uses 2.0 g, in every phase. How many calories in total suit a building phase is covered in the article on the calorie surplus.

Why it stays at 2 g on a diet

In a deficit, protein takes on a second job: it protects your muscle from being broken down as well. The bigger the deficit and the leaner you are, the more that matters. That's why your protein doesn't drop with your calories. It stays at 2.0 g per kilo, so it makes up a larger share of what you eat.

A review of strength-trained people on a diet arrives at 2.3 to 3.1 g per kilo of fat-free mass, trending higher with a larger deficit and lower body fat (Helms et al., 2014). The reference point is important: fat-free mass, not body weight. At 80 kg (176 lb) and 20 percent body fat, that's 64 kg of fat-free mass, so 147 to 198 g of protein a day. Converted to body weight, that comes to 1.8 to 2.5 g per kilo. The 2.0 g in the calculator falls within that range. If you're already very lean and running a large deficit, you can go up to 2.2 g. How big the deficit itself should be is explained in the article on the calorie deficit.

Which weight do you use if you're overweight?

Your goal weight. Your protein needs depend on your fat-free mass, not on your body fat. If you carry a lot more fat, your current weight would give you a figure that's higher than necessary and hard to eat in everyday life.

An example: you weigh 90 kg (198 lb), your goal is 80 kg (176 lb), and you're on a diet. With your current weight, it would be 2.0 × 90 = 180 g a day. With your goal weight, it's 2.0 × 80 = 160 g. The difference of 20 g is roughly 90 g of chicken breast every day. The calculator does this automatically: if your goal weight is below your current weight, it calculates protein and fat with your goal weight.

How to spread protein across the day

Over three to four meals, each with a clear protein source. A review recommends 0.4 g per kilo per meal for muscle growth, spread across at least four meals. At the top end, 2.2 g a day, that's up to 0.55 g per kilo per meal (Schoenfeld & Aragon, 2018). At 80 kg, that's 32 to 44 g per meal. With 2.0 g a day over four meals, you land at around 40 g.

• Protein source first: For every main meal, think first about where the protein comes from, then build the rest of the meal around it.
• Not just on training days: Keeping and building muscle carries on during rest days. Your needs stay the same.
• Don't overrate timing: Protein before or after training both work, and the effect of a session lasts at least 24 hours (Jäger et al., 2017). The amount across the day matters more than the minute after training.

A sample day with 160 g of protein

This is what a day can look like at 80 kg in a building phase, so 2.0 g per kilo. The values are rounded averages and vary a little by product.

Every meal falls within the 32 to 44 g range. On a diet, protein stays at the same 160 g. What gets smaller are the carbs, for example less rice and fewer potatoes.

Do you need protein powder?

No. Protein powder gives you nothing you can't also get from normal food. Meat, fish, eggs, dairy and legumes also bring micronutrients and keep you fuller. Powder is simply practical when you'd otherwise struggle to reach your target amount, and the position stand of the International Society of Sports Nutrition also sees it as a convenient addition, not a must (Jäger et al., 2017). What I think is worth taking, such as creatine, and what you can skip is covered in the free Supplements guide.

Is a lot of protein bad for your kidneys?

Not if your kidneys are healthy, based on current evidence. A meta-analysis looked at 28 studies with 1,358 healthy adults that compared a high-protein diet of at least 1.5 g per kilo with normal or low intake. The change in kidney function, measured by glomerular filtration rate, did not differ between the groups (Devries et al., 2018). The values in this article all fall within the range studied there.

When to check with a doctor

If you have a known kidney disease or reduced kidney function, or a doctor has advised you to limit protein, the guidelines here don't apply to you. Clear your protein intake with your doctor first. The same goes if you take several medications and also want to use supplements. This article does not replace medical advice.