How much protein do I need to avoid losing muscle while losing weight?

Most evidence supports roughly 1.2 to 1.6 grams of protein per kilogram of body weight per day while in a calorie deficit, which for an 80 kg adult is about 95 to 130 grams a day. Adults aged 65 and over generally sit at the higher end because they lose lean mass more readily, and adding resistance training raises the useful ceiling further.

Why does protein matter more on a GLP-1 medication?

GLP-1 medicines reduce appetite sharply, so total food intake often falls fast, and protein is usually the first thing to drop. Studies of rapid weight loss show a meaningful share of the weight lost can be lean tissue rather than fat. Keeping protein intake up and doing some resistance training are the two levers shown to reduce that lean-mass loss.

Should I spread protein across the day or have it in one meal?

Spread it. Protein is used more effectively when divided across meals rather than concentrated into one sitting, so aiming for a similar amount at each of three meals is a practical approach. If appetite is low, a protein-led first meal makes the rest of the day easier.

How much protein do I need to avoid losing muscle while losing weight?

Most evidence supports roughly 1.2 to 1.6 grams of protein per kilogram of body weight per day while in a calorie deficit, which for an 80 kg adult is about 95 to 130 grams a day. Adults aged 65 and over generally sit at the higher end because they lose lean mass more readily, and adding resistance training raises the useful ceiling further.

Why does protein matter more on a GLP-1 medication?

GLP-1 medicines reduce appetite sharply, so total food intake often falls fast, and protein is usually the first thing to drop. Studies of rapid weight loss show a meaningful share of the weight lost can be lean tissue rather than fat. Keeping protein intake up and doing some resistance training are the two levers shown to reduce that lean-mass loss.

Should I spread protein across the day or have it in one meal?

Spread it. Protein is used more effectively when divided across meals rather than concentrated into one sitting, so aiming for a similar amount at each of three meals is a practical approach. If appetite is low, a protein-led first meal makes the rest of the day easier.

Protein target calculator

How much protein you need each day to hold onto muscle while you lose weight. Free, no sign-up, and the working is shown.

The short answer: while you are losing weight, most evidence supports about 1.2 to 1.6 g of protein per kg of body weight a day. For an 80 kg adult that is roughly 95 to 130 g. If you are 65 or over, or you do resistance training, the useful range shifts higher.

Your weight

Right now you are

Age

Resistance training

Enter your weight to see your range.

This is general information, not medical or dietary advice. If you have kidney disease or another condition affecting how much protein is safe for you, your clinician's advice comes first.

What that looks like in food

Protein per usual portion, so the grams mean something.

Food	Portion	Protein
Chicken breast	100 g cooked	31 g
Salmon fillet	100 g cooked	25 g
Greek yoghurt	100 g	10 g
Eggs	2 large	13 g
Tinned tuna	100 g drained	25 g
Lentils	100 g cooked	9 g
Tofu (firm)	100 g	14 g
Whey protein powder	1 scoop (30 g)	24 g
Cottage cheese	100 g	11 g
Chickpeas	100 g cooked	9 g

Logging a few days is the only way to see where you actually land. Track it free and the protein total is worked out for you.

Why this matters when you are losing weight

When you lose weight, you do not only lose fat. Some of what comes off is lean tissue, which includes muscle. That matters for more than how you look: muscle is where you keep strength, balance and a good chunk of your daily energy use, and it gets harder to rebuild as you get older.

Two things reliably reduce how much muscle you lose. The first is eating enough protein. In a controlled trial where people ate in a deficit alongside hard training, the higher-protein group gained lean mass and lost more fat than the lower-protein group (Longland et al., 2016). The second is resistance training, which is the signal that tells your body the muscle is worth keeping.

This gets more pressing on a GLP-1 medicine. Appetite drops sharply, total intake falls fast, and protein is usually the first thing to slide, because it is the least appealing food to force down when you are not hungry. That is exactly when a target is useful. If you are 65 or over the stakes are higher again, which is why the international position paper on protein for older adults recommends more, not less, than the standard adult guideline (Bauer et al., 2013).

How the range is worked out

No hidden formula. The calculator starts from 1.2 to 1.6 g per kg of body weight while you are losing weight, or 1.0 to 1.4 while maintaining. Being 65 or over adds 0.2 to both ends. Resistance training adds 0.2 to the top end. The ceiling is capped at 2.0 g per kg, because past that the evidence for extra benefit in this situation gets thin.

It is deliberately a range rather than one precise number, because that is what the evidence actually supports. Anyone giving you a single figure to the gram is adding certainty that is not there.

Getting there when your appetite is low

Eat the protein on your plate first, while you still have appetite to spend.
Anchor every meal with a protein before you fill in around it.
If a full plate is too much, a shake covers 20 to 25 g without volume. See the protein powder guide.
Greek yoghurt, cottage cheese, eggs and tinned fish are the low-effort staples.

More on the order you eat things, and why it changes how full you feel, in eat the protein first.

Sources

The g/kg ranges on this page come from the four papers below. Last reviewed 25 July 2026.

Food

Portion

Protein

Chicken breast

100 g cooked

31 g

Salmon fillet

100 g cooked

25 g

Greek yoghurt

100 g

10 g

Eggs

2 large

13 g

Tinned tuna

100 g drained

25 g

Lentils

100 g cooked

9 g

Tofu (firm)

100 g

14 g

Whey protein powder

1 scoop (30 g)

24 g

Cottage cheese

100 g

11 g

Chickpeas

100 g cooked

9 g

Why this matters when you are losing weight

How the range is worked out

It is deliberately a range rather than one precise number, because that is what the evidence actually supports. Anyone giving you a single figure to the gram is adding certainty that is not there.