How much protein should you eat on a GLP-1?

Start with the part most pages skip: the protein figures for people on these medications are proposals, not an established requirement. In 2025, four US obesity and nutrition societies published a joint advisory on nutrition during GLP-1 therapy.⁵ It notes that higher targets of 1.2 to 1.6 g per kilogram a day have been proposed during active weight loss, and suggests an absolute 80 to 120 g a day as a target that may be easier to follow. It also says it is unclear whether per-kilogram goals should use actual body weight, an adjusted or ideal weight, or fat-free mass.

That is not a reason to ignore the question. It is a reason to know where the number came from.

Where the figures actually come from

The extrapolation is reasonable. Rapid weight loss with a substantial lean-mass component is exactly the situation the first two rows were written for. It is still an extrapolation, which is why the advisory frames its ranges as proposals rather than as a requirement.

Why the question comes up at all

In the body composition analysis of the tirzepatide obesity trial, roughly three quarters of the weight lost was fat and roughly one quarter was lean mass.¹

The clause that gets dropped from the headlines is the important one: that ratio was broadly similar in the placebo group. This is what substantial weight loss looks like in general, not something distinctive the drug does to muscle. What is distinctive is the scale and the speed, which is why the ratio matters more here than in an ordinary diet.

The second reason is mechanical. These medications work by reducing appetite, and eating less of everything means eating less protein. So the intake that protects lean mass is the one that gets harder exactly when it starts to matter more.

The arithmetic

The recommendations are per kilogram of body weight, which has two consequences people miss.

Your number falls as you do. Somebody starting at 115 kg and reaching 85 kg has gone from 138 g to 102 g at the same rate. Carrying the starting figure forward is not harmful and it is no longer what the recommendation says.

Scaling off a high starting weight overshoots. Targets calculated from total body weight at a high BMI produce numbers most people cannot eat, which is why an adjusted body weight is standard practice clinically. The 2025 advisory flags the same uncertainty about which weight to use, and offers a fixed 80 to 120 g a day as a simpler alternative. If a calculator has told you 190 g, that is worth questioning rather than attempting.

Protein Buddy asks whether you are taking a GLP-1 when you set it up and raises the target accordingly, and you can change it to the number agreed with somebody who knows your history.

Protein is half of the answer

The research on preserving lean mass pairs protein with resistance training almost without exception, and the expert groups for older adults recommend exercise alongside the higher intake rather than instead of it.²

Two or three sessions a week that load the major muscle groups is the usual figure. What that looks like on a GLP-1, including on the weeks after a dose increase, is its own question.

The practical difficulty is not knowing the number, it is reaching it on a day when nothing appeals. What to eat when appetite is low is the page for that.

The line this page does not cross

These are prescription medications and this is general reference material, not medical advice. Your protein target is a decision for the clinician who prescribed yours, particularly if you have reduced kidney function, liver disease, or any condition where protein intake is already managed as part of your care.

If you are losing weight faster than expected, struggling to eat, or noticing weakness, that is a conversation with your prescriber rather than an adjustment to a number on a website.