Weight Loss Calculator

First the calculator finds the calories that keep your weight steady (TDEE): your basal metabolic rate from the Mifflin-St Jeor equation times an activity factor. A pound of body fat holds about 3,500 kcal (7,700 kcal per kg), so: • Daily deficit = (current weight − goal weight) × 3,500 ÷ (weeks × 7) • Calories to eat = TDEE − daily deficit Example: a 28-year-old man, 5 ft 8 in and 152 lb, moderately active, has a TDEE of about 2,533 kcal. To reach 141 lb in 10 weeks he needs to lose 11 lb, a deficit of 11 × 3,500 ÷ 70 = 550 kcal a day. He should eat about 1,983 kcal a day and will lose about 1.1 lb a week. 1 to 2 lb a week is generally considered sustainable. Without medical supervision, women are advised not to go under 1,200 kcal and men under 1,500 kcal a day. Your needs drop as you lose weight, so update the numbers from time to time.