Food & protein

How much protein on a GLP-1?

When a GLP-1 medication shrinks your appetite, protein is one of the things that can quietly drop. Here is what published guidance says about how much to aim for, which body weight to base it on, and when general numbers don't apply to you.

The minimum, and the ranges proposed during weight loss

For adults, the Recommended Dietary Allowance is 0.8 g of protein per kg of body weight per day^[1]. A 2025 joint advisory on nutrition with GLP-1 medications — from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society — notes that higher targets of 1.2–1.6 g/kg/day have been proposed during active weight reduction^[2]. The US Dietary Guidelines 2025–2030 use the same 1.2–1.6 g/kg range as a general goal^[3].

Which body weight to use

This matters more than it sounds. The advisory says it is unclear whether targets for people with obesity should use actual, adjusted or ideal body weight, and warns that actual weight can significantly overestimate protein needs^[2]. One 2025 review suggests capping the weight used at the weight you would be at a BMI of 30, and notes that no trials have directly measured protein needs in obesity^[4].

If your body composition has been measured, the advisory considers 1.5 g per kg of lean mass a more accurate basis; as a simpler alternative it suggests an absolute 80–120 g a day^[2].

A floor and a ceiling

The advisory says adult protein intake should not fall below 0.4–0.5 g/kg/day, and that prolonged intake at or above 2 g/kg/day should be avoided^[2].

Why protein comes up with GLP-1 medications

Some of the weight lost on these medications is lean mass. In a body-composition substudy of SURMOUNT-1 (tirzepatide), weight fell 21.3%, fat mass 33.9% and lean mass 10.9% over 72 weeks, compared with 5.3%, 8.2% and 2.6% on placebo — roughly three-quarters of the weight lost was fat^[5]. "Lean mass" on these scans is not the same as muscle: it also includes organs, bone and fluid^[6].

The advisory pairs adequate protein with strength training at least three times a week plus at least 150 minutes of moderate aerobic activity^[2]. Reviews describe resistance exercise as an effective way to limit muscle loss during weight loss, with protein helping but not guaranteeing it^[7].

When these numbers don't apply

Pregnancy, breastfeeding and adolescence have their own reference values^[1], and people with chronic kidney disease are generally advised to eat less protein, not more, before dialysis^[8]. In these situations — or with a medical diet, a history of disordered eating, or trouble keeping fluids down — ask your clinician or a dietitian for a target.

General information, not medical advice. Your clinician or a dietitian can set a target for you.