GLP-1 Protein & Macro Calculator

How the calculator works

None of the arithmetic is difficult. What matters is that every coefficient in it traces to a peer-reviewed source.

• BMR (Mifflin-St Jeor 1990, PMID 2305711) [1]:
  Male: 10×W(kg) + 6.25×H(cm) − 5×age + 5
  Female: 10×W(kg) + 6.25×H(cm) − 5×age − 161
• TDEE (FAO/WHO/UNU 2001 PAL multipliers) [13]: BMR × {1.2, 1.375, 1.55, 1.725, 1.9} — running from sedentary at the bottom to extremely active at the top, through light, moderate and very.
• Caloric deficit (Hall 2011, PMID 21872751) [10]: a shortfall of 500 kcal a day works out at about 0.45 kg a week once things settle. In practice it comes off slower than that, because metabolism adapts downward as you lose.
• Protein tier selection (see below).
• Per-meal split (Mamerow 2014, PMID 24477298) [5]: spreading protein evenly over 3 meals raised muscle protein synthesis across the day by roughly 25%, against loading it into one.

The protein tier ladder

Five tiers, and each one is somebody's published recommendation rather than a round number:

• 0.8 g/kg/day — the RDA, which covers a sedentary adult holding steady and almost certainly does not cover anyone losing weight on a GLP-1.
• 1.0-1.2 g/kg/day — what PROT-AGE 2013 [2] asks of a healthy older adult at maintenance.
• 1.2-1.6 g/kg/day — PROT-AGE again where illness or training is involved, ESPEN 2014 [8] for older adults with disease, and the bottom of the ISSN 2017 [4] range for active people.
• 1.6-2.0 g/kg/day — the ISSN 2017 [4] figure for active people, and where Neeland 2024 [9] puts anyone on a GLP-1.
• 2.0-2.4 g/kg/day — the high arm of Longland 2016 [3], which added lean mass across 4 weeks of severe deficit plus lifting; Mettler 2010 [7], holding lean mass in trained athletes while losing weight; and the contest-prep range in Helms 2014 [6].

The GLP-1 bump

Say you are on a GLP-1, or about to start one, and the target moves up a tier. The reason sits in the body-composition substudies of STEP-1 [11] and SURMOUNT-1 [12]: left alone, without protein and resistance training, somewhere between 25 and 45% of what comes off is lean tissue. and the Neeland 2024 [9] review on GLP-1 lean mass mitigation specifically recommends targeting the higher end of the protein range (1.6-2.3 g/kg fat-free mass) for this population. The bump is the clinical translation of that finding.

What this calculator does NOT do

• It cannot see your body composition. The target is worked from total body weight, not fat-free mass. Trials do it properly, off a DXA scan, and that is more precise — but for use at home, total weight stands in well enough.
• It knows nothing about your kidneys. With chronic kidney disease — an eGFR under 60 — the higher tiers are a conversation for your nephrologist before they are a plan.
• It writes no meal plan. Targets are all it produces, and the plan is yours to build — ideally with a registered dietitian.
• It stands behind the conversation with your prescriber, never in front of it, and least of all where diabetes, kidney disease or anything else bearing on nutrition is involved.

Important disclaimer

Educational only. This is neither medical advice nor a dietary prescription. Every published recommendation behind it was drawn from healthy adults and healthy older adults, which means none of it transfers cleanly to chronic kidney disease, advanced liver disease or a metabolic disorder. With any of those, take the targets to a registered dietitian or the clinician who prescribes for you before acting on them. Each coefficient is cited to the primary source it came from, so any of them can be checked.

Related tools and research

• Semaglutide and muscle mass loss — the muscle-loss problem this calculator exists to work against
• Loose skin after rapid GLP-1 weight loss — downstream effect of inadequate lean-mass preservation
• GLP-1 BMI calculator — where you start, and where each trial endpoint would put you
• GLP-1 weight loss calculator — week-by-week trial projections