Protein shakes: how much protein do you actually need?

You're in the changing room after training, shaking 30 grams of whey into your bottle. Exactly the scoop the label tells you to use. The question almost nobody asks: did you still need those 30 grams today?

Whether a protein shake is healthy depends less on the shake than on what was already on your plate that day. I see it with nearly every man who trains seriously. He counts his shakes, but not his eggs, quark, chicken and bread.

Most men hit their protein target before the bottle is empty.

Are protein shakes healthy?

For most healthy men a protein shake is healthy in the sense that it can do little harm. Whey is simply milk protein, filtered out of the watery part and dried, with the same building blocks as quark, chicken or eggs. So a shake isn't special, though it can be handy.

What a shake doesn't do is build muscle you couldn't have built from food. The meta-analysis by Morton and colleagues in the British Journal of Sports Medicine pooled the research on protein supplements during resistance training (PMID 28698222). Extra protein helped, but the effect clearly flattened out.

Above roughly 1.6 grams of protein per kilo of bodyweight per day, the researchers saw no further muscle growth. So there is a ceiling. You'll find that ceiling on almost no supplement site.

One thing worth checking: what else is in the tub. Some powders carry a fair amount of sugar, sweeteners or fillers. Read the label as critically as you'd read the one on a packet of biscuits.

A shake is a tool, not an ingredient.

How much protein do you need per day?

The Dutch Voedingscentrum puts the general need for adults who don't train hard at around 0.8 grams of protein per kilo of bodyweight per day. For an 85 kilo man that works out at about 68 grams. Train seriously with weights and the need sits higher, somewhere between 1.6 and 2.0 grams per kilo.

The Gezondheidsraad sets the Dutch dietary reference values and works from a comparable baseline for healthy adults. Athletes sit outside that. They process more building material, simply because there is more to repair.

The table below gives you a practical guide per situation.

Work it out once for yourself. At 85 kilos and strength training you land on 135 to 170 grams a day. That sounds like a lot, but 250 grams of low-fat quark, 150 grams of chicken breast and three eggs already add up to over 75 grams.

The rest comes from bread, dairy, pulses and your evening meal. Spread it over three or four eating moments and 30 to 40 grams a time gets you there. Only if you keep falling short by the end of the day does a shake get interesting.

Does a shake work better than plain food?

Not measurably better. In Morton's analysis the source of the protein mattered little, as long as your total daily intake was on point (PMID 28698222). Whey absorbs faster, but in healthy men that difference doesn't translate into more muscle over the long run.

Take two men of 85 kilos who train three times a week. The first eats 150 grams of protein from food and drinks two shakes on top. The second eats the same 150 grams and drinks nothing.

On paper they differ by 50 grams of protein a day. In muscle growth, probably nothing, since both already sit well above 1.6 grams per kilo. The first man just has a pricier shopping list.

Real food has one advantage powder lacks: fullness. 250 grams of low-fat quark keeps you quiet for hours, a shake barely an hour. If you're losing fat, that counts for more than absorption speed.

Food also brings iron, zinc, vitamin B12 and fats. A scoop of powder brings protein, and little else. My position is simple: count what you eat first, buy a tub second.

What does a lot of protein do to your kidneys?

In healthy kidneys, the research doesn't point to damage from a lot of protein. Devries and colleagues compared higher protein intakes with normal or lower intakes in healthy adults in the Journal of Nutrition (PMID 30383278). Kidney function did not differ between the groups.

Your kidneys do work harder on a lot of protein. They filter more, which is called hyperfiltration. In healthy kidneys that looks like a normal adaptation, not wear and tear.

That's not a free pass. If you have a known kidney condition, diabetes or high blood pressure, the considerations are different. Discuss a high protein intake with your GP first in that case.

What does change is your blood.

Which blood values shift on a high protein intake?

Your liver breaks protein down into urea, which your kidneys excrete. Eat a lot of protein and your urea often runs higher than in a man eating 80 grams a day. Your creatinine can rise a little too, especially with plenty of muscle and plenty of meat.

At many laboratories the reference for urea sits somewhere between 2.5 and 7.5 mmol/l. An athlete eating 180 grams of protein a day can sit at the top of that range with nothing wrong. A doctor therefore looks at the whole picture, not one loose number.

Creatinine is even more confusing. It's a breakdown product of creatine from your muscles, so more muscle mass or a creatine supplement pushes the value up. How that works is covered in our piece on creatine and your creatinine.

Your eGFR is calculated from your creatinine. If your creatinine rises through muscle or powder, your calculated eGFR drops with it. That can look alarming on paper while your kidneys simply do their job.

Albumin in your blood usually barely moves with your protein intake in healthy men. That surprises a lot of men. Eating more protein doesn't automatically mean more protein in your blood.

The combination of values says more than any single number. We take that further in protein, creatine and your kidneys and in blood values for athletes.

When is a protein shake actually useful?

A shake is useful when time, appetite or planning get in the way. Train at 9pm and fancy no chicken afterwards, and 30 grams of whey beats nothing. When you're losing fat, powder also helps keep protein high while your calories stay low.

I drink a shake myself on a day with three meetings and a late session. Not because it works better, but because the alternative simply doesn't happen. That's more honest than pretending there's magic in the tub.

Some groups do fall short sooner. Vegetarians and vegans who eat few pulses, men over 65 with a small appetite, and anyone losing weight fast. For them the gap between 90 and 140 grams of protein a day isn't a detail.

Which supplements add something and which don't is laid out in our overview of supplements for men.

How much protein is too much?

Above roughly 2.0 to 2.4 grams per kilo per day there is little left to gain. According to Morton, the extra muscle growth already stops around 1.6 grams per kilo (PMID 28698222). What you eat above that mostly crowds out vegetables, fibre and carbohydrates from your plate.

At 85 kilos, 2.4 grams per kilo means over 200 grams of protein a day. That's eight tins of tuna. Few men keep that up, and they don't need to.

There's one more sum almost nobody does. A kilo tub of whey costs around 25 euros and yields roughly 33 scoops. Drink two a day without needing that protein and you're mostly buying expensive powder.

If you have a known kidney condition, the considerations differ and this is a conversation for your GP. If you want to see where your kidney values sit now, the Kidney Function test gives insight there. For a wider view of your blood values, the Basic Health Checkup looks at several values at once.

Do this before you buy a new tub. Write down what you eat across three normal days and count the grams of protein. If you land above 1.6 grams per kilo, a shake is mostly buying you convenience.

If your urea or creatinine looks high, tell your GP how much protein you eat and whether you use creatine. That context changes how a result is read. Your GP can help you decide whether further steps are needed.

References

• Morton RW, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018. PMID 28698222.
• Devries MC, et al. Changes in kidney function do not differ between healthy adults consuming higher- compared with lower- or normal-protein diets. J Nutr. 2018. PMID 30383278.
• Voedingscentrum. Protein. 2024. voedingscentrum.nl
• Gezondheidsraad. Dietary reference values for protein. 2021. gezondheidsraad.nl

Every blood test result at Caliber includes a professional assessment by a BIG-registered doctor. For treatment decisions, always discuss your results with your GP.