Free GLP-1 protein calculator. Enter your weight, sex, and age for a daily protein target (1.2–1.6 g/kg) to protect muscle while losing weight on Ozempic, Wegovy, Zepbound, or Mounjaro — plus per-meal and fiber goals.
GLP-1 medications like Ozempic and Zepbound work by curbing appetite — but eating far less can cost you muscle as well as fat. This tool sets a daily protein target to protect your lean mass while you lose weight.
Whenever you lose weight, some of what you shed is lean tissue, not just fat. The fast, deep appetite drop from a GLP-1 medication can make that worse: in the semaglutide and tirzepatide trials, a large share of the weight lost — often around 25% to 40% — was fat-free mass, which includes muscle.
Two things blunt that muscle loss in a calorie deficit: enough protein and resistance training. This calculator handles the protein side — it estimates how much you need each day to give your muscle the best chance of staying put.
The Recommended Dietary Allowance for protein is 0.8 grams per kilogram of body weight. That figure is a floor — the amount set to prevent deficiency in a weight-stable adult — not a target for someone actively, and quickly, losing weight.
During intentional weight loss, higher protein intakes protect lean mass better. This calculator uses 1.2–1.6 g/kg, the range supported by the higher-protein weight-loss research and by the Academy of Nutrition and Dietetics / Dietitians of Canada / ACSM position on protein for active adults (which runs up to 2.0 g/kg). A 2025 joint advisory on nutrition during GLP-1 therapy from four clinical societies proposes this same range — drawn from the broader weight-loss evidence base, since GLP-1-specific trials are still emerging.
Total protein matters most, but timing helps too. Your body builds muscle best when protein arrives in steady doses, so aim for 25–30 grams of protein at each of three to four meals rather than saving most of it for dinner — the pattern shown to stimulate more muscle protein synthesis over a day.
On a GLP-1 that can be genuinely hard: appetite is low and meals are small. Front-loading protein — eating it first, before you fill up — is the practical fix most dietitians suggest. If you'd rather not build it yourself, our protein-forward GLP-1 meal plan spreads this much protein across seven days of real recipes, and the GLP-1 diet guide covers the rest of what changes about eating.
GLP-1 medications slow how quickly your stomach empties, and constipation is one of the most common side effects. Hitting the fiber target shown above — the DRI Adequate Intake for your age and sex — helps, but increase fiber gradually and drink plenty of water, or you can trade one kind of discomfort for another.
Want the full picture on your calories and macros? Pair this with the protein calculator for activity-based targets, or the main MyPlate calculator for a full food-group plan.
Institute of Medicine (2005). *Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids* — the protein RDA (0.8 g/kg) and the Total Fiber Adequate Intakes (built from the 14 g per 1,000 kcal rule).
Phillips SM, Chevalier S, Leidy HJ (2016). "Protein requirements beyond the RDA," *Applied Physiology, Nutrition, and Metabolism* — the case for higher protein during energy restriction. Thomas DT, Erdman KA, Burke LM (2016). Academy of Nutrition and Dietetics / Dietitians of Canada / ACSM joint position on nutrition and athletic performance (1.2–2.0 g/kg).
Mozaffarian D, et al. (2025). "Nutritional priorities to support GLP-1 therapy for obesity," *Obesity* — the joint advisory of the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society, which proposes 1.2–1.6 g/kg during active weight reduction on GLP-1 therapy.
Mamerow MM, et al. (2014). "Dietary protein distribution positively influences 24-h muscle protein synthesis," *The Journal of Nutrition* — the even, ~25–30 g-per-meal distribution finding. Lean-mass-loss figures are from the STEP 1 (semaglutide, ~38% of weight lost as lean mass) and SURMOUNT-1 (tirzepatide, ~26%) body-composition analyses.
A common target for preserving muscle during weight loss is 1.2–1.6 grams of protein per kilogram of body weight per day — for a 90 kg (about 200 lb) person, roughly 108–144 g. That's well above the 0.8 g/kg RDA. Enter your weight above for your own range, and confirm any big diet change with your prescriber.
They don't target muscle directly, but rapid weight loss from any cause takes some lean mass with the fat. In the semaglutide and tirzepatide trials, a sizable share of the weight lost — often around a quarter to 40% — was fat-free mass. Eating enough protein and doing resistance training are the two things shown to protect muscle while you lose weight.
Aim for about 25–30 grams of protein per meal, across three to four meals, rather than one big protein hit at dinner. Spreading it out is linked to more muscle protein synthesis over the day. On a GLP-1, eat your protein first while your appetite allows.
The 0.8 g/kg RDA is the minimum to prevent deficiency in a weight-stable adult — it isn't the goal when you're actively losing weight. During a calorie deficit, higher protein (1.2–1.6 g/kg) does a better job of protecting muscle, which is why this calculator shows the RDA only as a floor.
No. This is a general nutrition tool, not medical advice about your medication. Protein needs can be different if you have kidney disease or other conditions, so use this as a starting point and coordinate with the care team that prescribed your GLP-1.