How much protein do you actually need? The number the research supports
Around 1.6 grams per kilogram of body weight per day is where the benefit to muscle plateaus, from a meta-analysis of 49 trials and 1,863 people. While losing weight, 1.8 to 2.2 grams is commonly recommended, because a body short of energy pulls more protein into use as fuel. Timing across the day matters far less than the daily total.
Protein is the one nutrient where the popular advice and the research have mostly converged, and where the remaining argument is about a fairly narrow range rather than about the direction.
Where does the 1.6 gram figure come from?
From Morton and colleagues (2018), a pooled analysis of 49 randomised trials covering 1,863 people who were doing resistance training. Gains in lean mass rose with protein intake up to about 1.6 grams per kilogram of body weight per day, and then flattened.
Flattened does not mean harmful. It means the next gram bought nothing measurable, which is a different and more useful claim than "more is bad".
Do you need more while losing weight?
Most likely, yes. When energy is short the body is more willing to use protein as fuel, so more of what you eat is burned rather than kept. Recommendations in a deficit commonly sit between 1.8 and 2.2 grams per kilogram.
There is a second reason that has nothing to do with metabolism: protein is the most filling of the three macronutrients per calorie. In a deficit, that is worth as much as the muscle protection.
Do you have to eat it every three hours?
No. The idea that muscle protein synthesis needs topping up on a schedule was drawn from short laboratory measurements and has not held up as a requirement for real-world results.
Spreading protein across three or four meals is a reasonable default, mostly because it is easier to reach a high total that way than by trying to eat all of it at dinner. But the total is the part that matters, and the schedule is the part that does not.
Does high protein damage your kidneys?
Not in people with healthy kidneys. This belief comes from advice given to patients who already have kidney disease, where restricting protein is genuinely appropriate — and it was generalised to everybody else, which the evidence does not support.
The distinction matters both ways: if you have existing kidney disease, this article is not the guidance to follow, and your doctor's is.
Is whey protein necessary?
No. It is food in a convenient shape, and its advantage is convenience rather than any property the protein in eggs, fish, chicken or tofu lacks.
It becomes genuinely useful when the daily target is hard to hit with meals alone — which is common at 2 grams per kilogram for someone eating in a deficit and short on appetite. Use it for that reason, not because a scoop does something a meal cannot.
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