Daily calories, estimated honestly.
Estimate how many calories your body burns at rest and on a typical day with the Mifflin-St Jeor equation, a standard formula for adults, plus the calorie deficit range the obesity guidelines use for gradual weight loss.
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Estimates, not measurements. Real needs vary with body composition, health conditions and medications.
The method, in the open.
Resting calories
The Mifflin-St Jeor equation: 10 times weight in kilograms, plus 6.25 times height in centimeters, minus 5 times age, then add 5 for men or subtract 161 for women. It estimates what your body burns at complete rest.
Daily needs
Resting calories times an activity factor, from 1.2 for mostly sitting to 1.9 for a physical job plus hard training. The factors are standard estimates, which is why the result is a starting point, not a prescription.
The deficit range
The 2013 obesity guideline from the American Heart Association, the American College of Cardiology and The Obesity Society uses a daily deficit of 500 or 750 calories, or diets of about 1,200 to 1,500 calories a day for women and 1,500 to 1,800 for men. Very low-calorie diets, under 800 calories a day, belong only in a medical care setting.
Eating less means eating well matters more.
GLP-1 medications change how hungry you feel, so many people eat noticeably less. A 2025 advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society puts enough protein and strength training among its nutrition priorities for people on GLP-1 therapy, to help preserve lean mass. Your provider and care team can help you set targets that fit your treatment.
Common questions.
How many calories should I eat to lose weight?+
What is the difference between BMR and maintenance calories?+
How accurate is this?+
Is what I enter saved?+
Where the numbers come from.
- Mifflin et al., A new predictive equation for resting energy expenditure in healthy individuals, American Journal of Clinical Nutrition (1990) (opens in a new tab)
- 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults (opens in a new tab)
- Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory from the ACLM, ASN, OMA and The Obesity Society (2025) (opens in a new tab)
Educational, not medical advice, and not a diagnosis. Results are estimates from published formulas and population data. A licensed provider makes every treatment decision. For a medical emergency, call 911.
Other numbers worth knowing.
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