Calorie Deficit Calculator with Goal Date
Calories to reach your goal date
Mifflin-St Jeor equation, PAL value and 1 kg of body fat ≈ 7,700 kcal.
The calculator estimates total daily energy expenditure with the Mifflin-St Jeor equation and the PAL value, then spreads the required energy deficit (1 kg of body fat ≈ 7,700 kcal) across the days until your goal date. A loss of 0.5 to 1 percent of body weight per week is a commonly cited practical guideline.
How the calorie deficit calculator works
First, basal metabolic rate is estimated with the Mifflin-St Jeor equation and multiplied by the PAL value to get total daily energy expenditure. The difference between current and goal weight is multiplied by roughly 7,700 kcal per kilogram of body fat (Wishnofsky, 1958). This total deficit is spread evenly across the days until the goal date and subtracted from daily expenditure.
What pace is realistic?
Helms et al. (2014) cite a loss of 0.5 to 1 percent of body weight per week during a diet phase as a guideline for preserving as much muscle mass as possible. If the pace is faster, the calculator flags it and shows the date the goal would be reached at 1 percent per week. If the calculated intake falls below the estimated basal metabolic rate, a note appears as well.
Why 7,700 kcal is only an approximation
Hall et al. (2011) show that a constant deficit does not lead to linear weight loss: as body weight drops, energy expenditure drops too, so weight loss slows over time. The calculator therefore gives a starting value that should be adjusted to actual body weight along the way.
Hold your deficit day to day
GymLog AI logs meals via chat, voice or photo and always shows how much of your daily target is left.
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- Mifflin, M. D., et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 51(2). PubMed
- Wishnofsky, M. (1958). Caloric equivalents of gained or lost weight. Am J Clin Nutr, 6(5). PubMed
- Hall, K. D., et al. (2011). Quantification of the effect of energy imbalance on bodyweight. Lancet, 378(9793). PubMed
- Helms, E. R., et al. (2014). Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. JISSN, 11:20. jissn.biomedcentral.com