The published target for protein during active weight reduction is 1.2 to 1.6 g per kg of body weight a day, from a 2025 joint advisory by the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society (PMID 40673264). The same advisory offers 80 to 120 g a day as an absolute alternative for people who find a per-kilogram calculation hard to act on.
That is between one and a half and twice the general adult reference intake of 0.8 g per kg. The reason it rises on a GLP-1 is not the drug itself but the size of the energy deficit the drug makes possible, and the fact that appetite suppression makes hitting any intake target harder rather than easier.
- Target during active weight reduction: 1.2 to 1.6 g of protein per kg of body weight a day. The general adult reference intake is 0.8 g/kg.
- An absolute target of 80 to 120 g a day is offered as an alternative that is easier to stick to.
- The same advisory states that extra protein alone is likely inadequate to preserve muscle without structured resistance training.
- Protein should not fall below 0.4 to 0.5 g per kg a day, below which muscle atrophy and functional impairment follow.
- Eating the protein part of a meal first is the one mechanical tactic the advisory names, because meals often end early when appetite is blunted.
Where the number comes from
The advisory is the first document from four major US societies aimed specifically at nutrition alongside GLP-1 therapy, and it is careful about how it states the figure. It describes 1.2 to 1.6 g/kg body weight/day as a target that "have also been proposed during active weight reduction", notes a slightly higher 1.2 to 1.7 g/kg range where strength training is involved, and records that recommendations based on adjusted body weight run from 1.2 to 2.0 g/kg of adjusted body weight a day.
None of those is a hard threshold with a trial behind it. They are consensus positions drawn from the wider literature on preserving lean mass during an energy deficit, applied to a setting where deficits are now larger and more sustained than diet alone usually produces. Treat the range as a target to aim at rather than a line to cross.
What the target is in grams, by body weight
The arithmetic is one step: divide your weight in pounds by 2.2 to get kilograms, then multiply by 1.2 and by 1.6 for the two ends of the range. Rounded figures:
| Body weight | In kilograms | At 1.2 g/kg | At 1.6 g/kg |
|---|---|---|---|
| 150 lb | 68 kg | 82 g | 109 g |
| 180 lb | 82 kg | 98 g | 131 g |
| 200 lb | 91 kg | 109 g | 145 g |
| 220 lb | 100 kg | 120 g | 160 g |
| 250 lb | 113 kg | 136 g | 181 g |
| 280 lb | 127 kg | 152 g | 203 g |
| 300 lb | 136 kg | 163 g | 218 g |
Read the bottom rows and the problem with a per-kilogram rule at higher body weights becomes obvious. At 300 lb, the top of the range is 218 g of protein a day, which is roughly 870 kcal from protein alone and a difficult amount of food to get through on a drug whose main effect is to make you want less food.
Which weight you multiply matters
This is why the advisory raises adjusted body weight. Lean mass does not scale with total weight in a straight line, so scaling a protein target to total body weight overshoots at the high end. Clinical practice commonly uses an adjusted figure that sits between ideal and actual weight, which is also why the advisory quotes a wider 1.2 to 2.0 g/kg range when adjusted weight is the basis: the two adjustments partly cancel.
Which figure applies to you is a clinical judgement rather than a calculation, and it is a reasonable thing to ask a prescriber or dietitian to settle. That ambiguity is the practical argument for the absolute target.
The absolute target, for people who want one number
The advisory states that setting an absolute protein target of 80 to 120 g a day may enhance adherence while ensuring adequate intake. It sidesteps the per-kilogram argument entirely and lands inside the range for most adults in the table above. For anyone who has tried and abandoned a per-kilogram calculation, it is the more useful of the two framings, because a target you actually track beats a more precise one you do not.
What the protein is protecting
Weight lost on any substantial energy deficit is a mix of fat and lean tissue, and the GLP-1 trials are no exception. The body composition data is covered in detail in our piece on muscle loss on a GLP-1, including what the SURMOUNT-1 DXA substudy measured and why lean mass is not the same thing as muscle. The short version is that the proportion of lean mass lost on these drugs looks similar to what diet-induced weight loss of the same size produces, which means the absolute amount is larger simply because the total loss is larger.
Protein intake is one of two interventions with a plausible claim to change that split. It is the easier one to measure and the weaker one on its own.
Protein alone will not do it
The advisory is unusually direct on this point, stating that increased protein intake alone is likely inadequate to support the preservation of muscle mass in the absence of structured resistance or strength training. That sentence is worth reading twice, because the protein half of the message travels much further on social media than the training half.
Resistance training is the intervention with randomised evidence behind it in this setting, and protein intake is best understood as what makes that training productive rather than as a substitute for it. Hitting 140 g a day and doing nothing else is a worse plan than hitting 110 g and lifting twice a week.
Hitting the number when you are not hungry
The difficulty on a GLP-1 is not knowing the target, it is that total intake falls sharply while the protein figure stays where it is. Protein has to occupy a much larger share of a much smaller amount of food. Five things make that tractable:
- Eat the protein part of the meal first. This is the one mechanical tactic the advisory names, on the grounds that meals frequently end before the plate does. Whatever is eaten first is what gets eaten.
- Spread it across every eating occasion. Three meals each carrying 30 to 40 g gets most people inside the range without any single meal being large.
- Count on smaller, more frequent occasions rather than trying to restore the size of meals you ate before. Four or five small protein-containing occasions are easier than three normal ones.
- Use liquid protein when solids are the obstacle. Nausea and early fullness tend to affect solid food more than liquids, and a shake delivers 25 to 30 g in a volume that is easier to finish.
- Weigh and log for a fortnight, then stop. Most people are 30 to 50 g below where they assume they are. Two weeks of measurement recalibrates the estimate, after which eyeballing works.
The advisory also asks for adequate fluids and fibre from foods alongside this, with the caveat that high-fibre foods can temporarily worsen constipation during the adjustment period. The broader diet picture, including the foods that reliably make side effects worse, is in our guide to what to eat on a GLP-1, and the calorie side of the same arithmetic is in the GLP-1 calorie guide.
The floor is the part to watch
The advisory sets a lower bound as well as a target: protein intake in adults should not fall below 0.4 to 0.5 g per kg a day, below which muscle atrophy and functional impairment follow. At 200 lb that floor is roughly 36 to 45 g a day, which sounds easy to clear and is not always, because appetite suppression on these drugs can be strong enough that total intake collapses rather than merely shrinks.
Two signals are worth raising with a prescriber rather than managing alone: intake that has fallen so far that the floor is in question, and strength or function declining in daily tasks. Both are reasons to review the dose or the plan, and both are easier to act on early.
See where your weight loss is heading
Put your starting weight against the published trial averages and get a week-by-week pound figure.
A protein target is easier to hold onto when you can see what it is in service of. Running your starting weight through the GLP-1 weight loss calculator turns the trial percentages into pounds, and dividing the pounds by the months gives you a rate to set the protein number against.
FAQ
How much protein should you eat on a GLP-1?
The 2025 joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society puts it at 1.2 to 1.6 g per kg of body weight a day during active weight reduction, or 80 to 120 g a day as an absolute target. The general adult reference intake is 0.8 g per kg.
Is there a protein calculator for GLP-1 users?
The calculation is one multiplication, so a calculator adds little: divide your weight in pounds by 2.2 for kilograms, then multiply by 1.2 and 1.6 for the ends of the range. At 200 lb that is 109 g to 145 g a day. The harder question, which no calculator settles, is whether to scale to total body weight or to an adjusted weight at higher body weights.
Will eating more protein stop muscle loss on semaglutide?
Not by itself. The same advisory states that increased protein intake alone is likely inadequate to preserve muscle mass without structured resistance or strength training. Protein supports the training rather than replacing it.
How do you hit a protein target when you are never hungry?
Eat the protein portion of each meal first, since meals often end before the plate is finished. Spread intake across four or five smaller occasions instead of three normal-sized meals, and use liquid protein where solid food is the obstacle, since nausea and early fullness usually affect solids more.
How little protein is too little?
The advisory sets a floor of 0.4 to 0.5 g per kg a day, below which muscle atrophy and functional impairment follow. At 200 lb that is roughly 36 to 45 g a day. Intake that has fallen near that level is a reason to speak to a prescriber rather than to manage alone.
Does protein need to go up as you lose weight?
In grams, a target scaled to body weight falls as body weight falls, but as a share of what you eat it rises, because total intake drops faster. Someone eating 1,400 kcal a day with a 120 g protein target is taking about a third of their calories from protein, which is a very different plate from the one they ate before.
This article is for information only and is not medical advice. Protein targets interact with kidney function and other conditions, and the right figure for you is a decision for your prescriber or a registered dietitian.
Sources
- Mozaffarian D, Agarwal M, Aggarwal M, et al. Nutritional priorities to support GLP-1 therapy for obesity: a joint Advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. <em>Obes Pillars</em>. 2025;15:100181. PMID: 40673264
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1), including the body composition substudy. <em>N Engl J Med</em>. 2022;387(3):205-216. PMID: 35658024
- Wilding JPH, Batterham RL, Calanna S, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). <em>N Engl J Med</em>. 2021;384(11):989-1002. PMID: 33567185