Protein targets on a GLP-1: how the arithmetic works

A protein target is the simplest calculation on this site: body weight times a factor. The whole argument is about the factor, and the factor comes from the source you choose. The calculator offers three sourced ranges and a custom option; this page explains what each one is.

The three ranges

0.8 g/kg/day, the RDA. The Recommended Dietary Allowance set by the Institute of Medicine in its 2005 Dietary Reference Intakes. It is the intake estimated to meet the needs of nearly all healthy adults, meaning it prevents deficiency. It was not derived for people losing weight, and the weight-loss literature treats it as a floor.

1.2 to 1.6 g/kg/day, the weight-loss range. From the 2015 review by Leidy and colleagues in the American Journal of Clinical Nutrition, which summarised evidence that higher-protein diets in this range improve satiety, help preserve lean mass during energy restriction, and support weight maintenance afterwards, in adults with overweight or obesity.

1.4 to 2.0 g/kg/day, the training range. From the International Society of Sports Nutrition's 2017 position stand on protein and exercise, for people building or maintaining muscle with resistance training. The upper part of this range is aimed at people training hard, and the position stand discusses even higher intakes during aggressive energy deficits in trained individuals.

None of these sources studied GLP-1 users specifically. They are cited here because the relevant physiology, energy restriction with a risk to lean mass, is the same problem, and because they are the numbers clinicians usually reach for.

Which weight to multiply

The ranges are per kilogram of body weight. For someone at 80 kg, 1.2 to 1.6 g/kg is 96 to 128 g per day. At 130 kg the same factor gives 156 to 208 g, which many people find hard to eat, particularly with a reduced appetite. Some clinicians therefore calculate from a goal weight or an adjusted weight at high BMI. The calculator does not make that choice for you; it multiplies the weight you enter and shows the factor, so the assumption is visible.

Why the per-meal split matters

Reduced appetite is the mechanism of these drugs, and it is also the main obstacle to hitting a protein target. Splitting a 120 g target across three meals is 40 g each; across four it is 30 g. The per-meal figure in the calculator is there to make a plan concrete: what does 30 g look like at breakfast?

For orientation, approximate USDA values: 100 g of cooked chicken breast is about 31 g of protein, one large egg about 6 g, 100 g of Greek yogurt about 10 g, 100 g of cooked lentils about 9 g. These are averages from FoodData Central, not label values for a specific product.

When to get individual advice

Higher-protein intakes are not appropriate for everyone. People with chronic kidney disease, some liver conditions, or on certain medications should have a clinician or dietitian set the target. The calculator's custom option exists for exactly that case: enter the factor your clinician gave you, and the arithmetic is done the same way.

Trial data on lean-mass change during GLP-1 therapy, and the maintenance results from SURMOUNT-4 and STEP 4, are covered on Weight Loss on GLP-1s, a sister site in the FormBlends network.