These drugs work by making food less interesting, and that is also the reason eating well on them is harder than it sounds. A person who is rarely hungry does not forget to eat protein through carelessness; the signal that used to prompt the meal is gone. Before comparing what a plan charges on the price boards, it is worth knowing what the trials fed people and what they measured.
How much less people eat, measured directly
A double-blind trial randomized 72 adults with obesity to semaglutide escalated to 2.4 mg or placebo for 20 weeks, then sat them down to a lunch they could eat freely. The semaglutide group consumed 1,736 kJ against 2,676 kJ on placebo, an estimated treatment difference of −940 kJ and a reduction of 35% (P < 0.0001).[1]
The same participants reported less hunger, less prospective food consumption, more fullness and more satiety, all at P < 0.02, with better control of eating and weaker food cravings.[1] Notably, gastric emptying assessed indirectly by paracetamol absorption showed no delay at week 20 once body weight was accounted for.[1] The appetite change is central, and a slowed stomach is not the whole mechanism people assume it is.
That is one meal in 72 people rather than a food diary over a year, so it describes the mechanism rather than anyone’s habitual intake. It still sets the arithmetic. A plate roughly a third smaller carries roughly a third less of everything on it.
What the trial protocols actually prescribed
Most pivotal trials describe their food arm as a lifestyle intervention and leave it at that. STEP 3 is the exception worth reading, because the diet arm was the point. It randomized 611 adults to semaglutide 2.4 mg or placebo, and gave both groups a low-calorie diet for the first eight weeks plus intensive behavioral therapy across all 68 weeks, amounting to 30 counseling visits.[2]
Mean weight change was −16.0% against −5.7% on placebo, a difference of 10.3 percentage points (95% CI, −12.0 to −8.6). Weight loss of 15% or more was reached by 55.8% against 13.2%.[2]
Read the placebo arm and the lesson inverts. Structured eating support alone produced 5.7%, well above the 2.4% the lighter lifestyle arm of the flagship trial produced. The drug’s incremental contribution was correspondingly smaller here than in that trial. A diet program is not a garnish on the prescription; it moves the number on both sides of the comparison.
Why adequacy is the hard part
A 2026 consensus statement from three European obesity and dietetic bodies took up exactly this problem: reduced appetite, rapid loss, gastrointestinal side effects and changed eating behavior creating nutritional risk in some people. It synthesizes evidence on protein targets during weight loss, on dietary quality, and on mitigating gastrointestinal adverse events, and it lists longitudinal research on micronutrient status and macronutrient requirements as still outstanding.[3]
The gastrointestinal half of that overlaps with the first months of treatment, when nausea narrows what is tolerable as well as what is wanted, which the nausea article covers in its own terms. The nutritional half persists after the nausea settles, because the appetite suppression is the therapy rather than a side effect that passes.
Where the protein figures come from
The protein advice attached to these drugs is borrowed wholesale from general nutrition science, and it is worth seeing the size of the effect being borrowed. A meta-analysis of randomized trials compared protein intakes above the recommended dietary allowance against intakes at it. During energy restriction, the higher intakes attenuated lean-mass loss by 0.36 kg (95% CI, 0.06 to 0.67) across 14 comparisons. During resistance training they added 0.77 kg across three.[4] Under non-stressed conditions the difference was not significant, which is a useful boundary on the claim.
A separate meta-regression of 49 studies and 1,863 participants put a ceiling on it. Protein supplementation raised fat-free mass gains during resistance training by 0.30 kg (95% CI, 0.09 to 0.52) and one-repetition-maximum strength by 2.49 kg. The benefit then flattened: beyond a total intake of about 1.6 g per kilogram per day, there was no further gain.[5] The effect also shrank with age and ran larger in people already resistance-trained.[5]
Neither analysis contains a single participant on a GLP-1 receptor agonist. They describe dieting and training adults, and the inference to this population is exactly that: an inference. That is the same gap the lean-mass evidence runs into from the other direction.
The trial that would close the gap has not reported
A protocol published in 2026 describes 232 adults starting semaglutide or tirzepatide, randomized four ways. The arms are control, home-based resistance exercise, protein supplementation targeting 1.6 g per kilogram per day, and both combined. Quadriceps cross-sectional area on MRI is the primary outcome at six months.[6] It is a protocol. No results exist yet.
So a seller quoting a gram target as validated for GLP-1 users is quoting a number from a different literature. The number may well be right. It has not been tested in the population being sold to, and that distinction belongs in any honest comparison of what a program includes across the seller index.
What this page is not
No target here is a recommendation for a particular person. Protein intake interacts with kidney function, with medication, with pregnancy and with age, and the consensus statement above exists precisely because the right answer is individual and clinical.[3] A prescriber or a registered dietitian is the place that conversation belongs.
One practical note is commercial rather than clinical. Coaching, food logging and check-ins were in both arms of the trial that measured them, so a plan charging a premium for that layer is charging for the comparator. What the money actually buys across formats is the subject of the oral board, and how any figure here was established is set out in the methodology.