This one is arithmetic rather than pharmacology. If protein stays the same percentage of what you eat and you eat considerably less, you are eating less protein — and the trials that report the percentage mostly do not report the grams. It is the same accounting problem as reading a lean-mass figure without its comparator.
What the trials measured
The review gathers the dietary data from incretin trials and finds that liraglutide generally maintains protein intake as a proportion of total energy, in the region of 13.9% to 17.5%. [1] That sounds like a reassuring finding and it is the wrong unit for the question being asked.
Those percentages come from liraglutide studies. The authors note the concern grows with more potent appetite suppression, which is where the newer drugs sit and where the dietary data are thinnest — the same ordering as the gap between the molecules on weight.
The gap where the outcome should be
Nobody has shown that this causes measurable harm. The review says comprehensive dietary data remain limited and that few studies have systematically tested whether reduced protein intake translates into declines in muscle mass, strength or physical performance.
So what exists is a plausible mechanism and an absence of outcome data — which is a different thing from a demonstrated risk, and a different thing again from nothing to worry about. The authors ask for longer trials with dietary assessment, body composition and function measured together.
What this page will not give you
A protein target. There are published ones, they vary by age, kidney function and body weight, and none of them is this desk’s to hand out.
What is safe to say is that appetite suppression is the mechanism you are buying, and that it does not discriminate between the food you wanted to cut and the food you did not. If you are older, or already losing weight fast, that is a conversation worth having with a clinician rather than with a checkout.
Nobody sells this alongside the drug
No seller on this roster includes dietary assessment, and the coaching products that do exist are sold separately and have been evaluated without randomization.
That is worth knowing before treating a subscription as a weight-management program. What arrives is the drug, and most people are not on it a year later — so the window in which any of this matters is usually short, and while it is open nobody is watching what you eat.