GLP-1 Calorie Calculator
On semaglutide or tirzepatide the usual problem is eating too little, not too much. This estimates your maintenance calories, the guideline deficit range, and how much of that budget the protein floor already claims — so a small appetite still covers what matters.
Maintenance estimate
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| Plan | kcal / day | Protein share |
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Common questions
How many calories should I eat on a GLP-1?
There is no GLP-1-specific calorie number. Clinicians work from your maintenance estimate and the standard obesity-guideline deficit of about 500–750 kcal/day; the risk on GLP-1s is undershooting because appetite drops, so the protein floor matters more than the calorie ceiling.
What if I'm eating far less than the target?
Very low intake without medical supervision risks muscle loss and nutrient gaps. The 2013 AHA/ACC/TOS obesity guideline's reduced-calorie diets start at 1,200–1,500 kcal/day for women and 1,500–1,800 kcal/day for men; going lower is a conversation for your clinician.
Which formula is this?
Mifflin-St Jeor (1990) for resting energy, multiplied by a standard activity factor. It is an estimate with a typical error of about ±10% for an individual.
How it's computed
Resting energy (Mifflin-St Jeor): 10 × kg + 6.25 × cm − 5 × age + 5 (men) or − 161 (women), times the activity factor (1.2 / 1.375 / 1.55 / 1.725). Deficit rows subtract 500 and 750 kcal (2013 AHA/ACC/TOS guideline) and are flagged when they fall under that guideline's 1,200 (women) / 1,500 (men) kcal starting floor. The protein share uses the joint advisory's 1.2–1.6 g/kg band at 4 kcal per gram. Not medical advice.
- Mozaffarian D, 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. Obesity. 2025;33:1475 (also Am J Lifestyle Med; PMC12125019).
- Sievenpiper JL, et al. Nutritional and lifestyle supportive care recommendations for management of obesity with GLP-1-based therapies: an expert consensus statement using a modified Delphi approach. Obesity Pillars. 2025 (published online 11 Nov 2025).
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247.
- Jensen MD, et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults. Circulation. 2014;129(25 Suppl 2):S102-38.
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