Calculate daily calorie needs (TDEE)
Your Total Daily Energy Expenditure (TDEE) is the number of calories your body burns each day. To lose weight, eat fewer calories than your TDEE. To gain weight, eat more. A deficit of 500 calories/day leads to roughly 0.5 kg (1 lb) of weight loss per week.
BMR (Basal Metabolic Rate) is the energy your body needs at complete rest. TDEE multiplies BMR by an activity factor to account for daily movement and exercise.