If you're trying to lose weight, one of the first questions you may ask is: How many calories should I eat per day? There isn't one calorie target that works for everyone. Daily energy needs vary with body size, age, sex, metabolism, and physical activity. NIDDK notes that calorie needs can differ based on all of these factors, which is why individualized planning is more useful than assigning the same calorie intake to everyone. A practical place to start is your TDEE, or To