How much protein do you need per day, and can your body really only use 25 g at once?

"Your body can only absorb 20 to 25 grams of protein at once, the rest is wasted." You have probably heard this at the gym or online. In 2023, a carefully designed study seriously challenged that idea. Let's look at what the data shows and how much protein per day actually makes sense.

Where does the 25 g per meal rule come from?

Earlier studies measured how quickly new muscle protein is built in the hours after training. They found that about 20 to 25 g of high-quality protein was enough to reach the maximum rate of that process in healthy young adults, and that more protein did not push it higher. That is where the idea of "wasted" protein comes from.

The catch is that these studies looked at a short window of time. They did not answer what happens to a larger amount of protein over the following hours.

What the 2023 study found

Researchers at Maastricht University published a study in Cell Reports Medicine in which healthy young men ate either 25 g or 100 g of protein after a whole-body workout ^[1]. Using labelled amino acids, they tracked where the dietary protein went over 12 hours.

The result: 100 g of protein produced a larger and longer anabolic response that lasted more than 12 hours. More of the protein was built into muscle rather than simply burned. In other words, the body does not throw away protein above 25 g. It just uses it more slowly and for longer.

An important caveat: the participants were healthy young men. The authors themselves stress that the results cannot be directly applied to other groups, such as older adults or people with medical conditions ^[1].

How much protein per day is enough?

For daily intake, the most useful data comes from a large meta-analysis in the British Journal of Sports Medicine, which pooled 49 studies with 1,863 participants who did resistance training for at least six weeks ^[2]. Protein improved strength and muscle mass, and the muscle-mass benefit stopped growing at a total intake of around 1.6 g per kg of body weight per day.

That figure is an estimate, not a hard cut-off. The authors note that people who want to be sure they are not missing out could go up to about 2.2 g/kg ^[2]. The benefit of extra protein was larger in people who already trained and smaller with increasing age.

What this means in practice

• Focus on the daily total, not a single meal. If your lunch is a big portion of meat or fish with 50 to 60 g of protein, it is not wasted.
• Spreading it out is about convenience. 3 to 4 meals with 25 to 40 g of protein each make the target easier to hit and keep you fuller, but they are not required.
• Food first, supplements second. Eggs, yoghurt, cheese, cottage cheese, meat, fish, legumes and tofu cover most people's needs. A protein shake is simply a convenient option.
• If you are losing weight, enough protein helps you keep your muscle and stay full for longer.

Who should be careful

Higher protein intakes are safe for healthy people, but if you have kidney disease or another chronic condition, discuss the amount with your doctor. The 2023 study was done in young men, so needs may differ in older adults and in people with medical conditions ^[1].

If you want to know how much protein is right for you and how to fit it into tasty meals, see how the personalised meal plan works.