Calorie Deficit Calculator
Frequently Asked Questions
How large should my calorie deficit be to lose weight safely?
A deficit of 500 calories per day is widely considered the safest effective target, producing roughly 1 pound of weight loss per week. Deficits larger than 1,000 calories per day increase the risk of muscle loss, nutrient deficiencies, and extreme hunger, making them harder to sustain and potentially harmful without medical supervision.
Why am I not losing weight even in a calorie deficit?
Common reasons include underestimating food portions, overestimating activity level, or failing to account for liquid calories. Water retention from high sodium intake, hormonal fluctuations, or starting a new exercise routine can also mask fat loss on the scale for 1 to 2 weeks even when your deficit is accurate and working.
Does exercise change my calorie deficit target?
Yes. If you add regular workouts, your TDEE increases and you should recalculate. The easiest approach is to select a higher activity multiplier in the calculator or add your average daily exercise calories to your TDEE, then subtract your deficit goal from the updated total to find your new daily calorie target.
How accurate is this calorie deficit calculator?
The calculator uses the Mifflin-St Jeor equation, validated as the most accurate BMR formula for most adults. Real-world accuracy is typically within 10 percent. Individual variation in metabolic rate, gut microbiome, and hormonal factors means results are best used as a starting estimate, refined by monitoring your actual weight trend over 2 to 3 weeks.
What is the minimum number of calories I should eat per day?
The American College of Sports Medicine recommends no fewer than 1,200 calories per day for women and 1,500 per day for men without medical supervision. Eating below these minimums risks nutrient deficiencies, muscle loss, fatigue, and metabolic slowdown. Always prioritize a moderate deficit that you can sustain over months rather than an extreme short-term cut.
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