How do you lose 80 lbs in a year?

Answer 1

You would need to lose (80 pounds / 52 weeks=) 1.54 pounds per week. A pound of fat contains about 3500 calories, so that means you'll need to lose (3500 x 1.54=) 5390 calories per week. To put that in terms of a daily calorie reduction, you'll need to decrease your daily caloric energy balance by 770 calories. You will then have to maintain this decreased intake and/or increased activity level indefinitely, which means making it a part of your life.