We all know that we gain weight when we eat too many calories, but you may be wondering, How many calories should I eat a day to lose weight? Bottom Line Personal asked weight-management specialist Holly Lofton, MD, that question…
To quantify the energy in foods and the energy our bodies use, nutritionists use units known as calories. One calorie is the energy required to raise the temperature of one gram of water by one degree Celsius. We need to consume a certain number of calories each day to carry out our body’s basic functions. At its simplest, weight management boils down to if you eat more calories than you burn in a day, you’ll gain weight…and if you eat fewer calories than you burn in a day, you’ll lose weight.
A calorie deficit simply means that you eat fewer calories than you burn every day. Theoretically, this should lead to weight loss.
But first you need to determine how many calories you’re burning each day. That figure is your total daily energy expenditure (TDEE). Once you know your TDEE, you’ll pick a daily calorie target just lower than it.
TDEE calculators: There are several good TDEE calculators and apps, including CalorieKing…Lose It!…and myfitnesspal. You enter information about your weight, height, sex, age and activity level, and the calculator estimates your TDEE.
But: TDEE calculators aren’t perfect. If you mischaracterize your level of physical activity, for example, your TDEE will be off. And weight loss isn’t as purely mathematical as we’d like to think. Our bodies store fat differently… medications can throw off weight-loss efforts…and insulin resistance and hormonal problems can make it more difficult to lose weight than it would seem on paper. Still, using a TDEE calculator and maintaining a deficit is a good starting point.
Some calculators tell you not just how many calories you need to maintain your weight, but how many to lose weight. But you can figure this out for yourself. Rule of thumb: For every 3,500-calorie deficit you achieve, you’ll lose one pound. Since a pound per week is a sustainable rate of weight loss, we normally split that 3,500 calories up over seven days, for a daily deficit of 500 calories. But depending on your TDEE, 500 calories could be an unrealistically large reduction, and you may need to divide your 3,500-calorie deficit over 14 days instead of seven, for a loss rate of one-half pound per week. Two examples…
#1: A 50-year-old man who weighs 230 pounds enters his information into a calculator and gets a TDEE of 3,000 calories per day. He subtracts 500 calories per day, eats 2,500 every day and loses one pound per week.
#2: The calculator tells a 32-year-old woman who weighs 155 pounds that she needs only 2,000 calories per day. She subtracts 250 calories per day, eats 1,750 calories daily, and loses one pound every two weeks.
