How Body Fat Affects Calories

Numerous different factors such as weight, height, gender and activity levels affect how many calories you should eat, but one of the main ones is your body fat levels. The number of calories you consume on a daily basis determines whether you lose, gain or maintain your weight and calorie balance is crucial in achieving your goal physique.

High Body-Fat Levels

When you have a high level of body fat, it's likely you'll be looking to lose weight. To do this you need to be in a calorie deficit, meaning you're consuming fewer calories than you burn. The average woman needs 11 calories per pound of body weight daily to maintain her weight, while the average man needs 14 calories per pound per day, according to nutritionist Nicole Cormier. At a higher level of body fat, this means you can eat more calories than a lighter person, as your body needs more calories. You still need to be in a deficit, however, so take 500 to 1,000 calories from your daily maintenance level to drop 1 to 2 pounds per week.

Low Body-Fat Levels

At a lower body-fat level, you don't need as many total calories to maintain your weight, though the same calories per pound guidelines still apply. This just means that when aiming to lose fat you'll have to lower your caloric intake further. Another consideration is that if your body fat is very low, you may actually be looking to gain weight, meaning you'll need to be eating in a caloric surplus, so you should raise your intake slightly above your maintenance level.

Larger Calorie Deficits

For someone of an average body-fat level, which is 25 to 31 percent for a woman and 18 to 24 percent for a man, large calorie deficits can be detrimental and lead to fatigue, lethargy and nutrient deficiencies. This isn't the case so much if you're carrying a high level of body fat and classified as obese though, writes nutritionist Lyle McDonald in "The Rapid Fat Loss Handbook." Those with high body-fat percentages have more stored body fat to burn, so they can tolerate bigger calorie deficits of 1,000 to 1,500 calories per day.

Genetic Differences

Some people are more prone to carry excess body fat than others. Naturally skinny, slender people are referred to as ectomorphs, while those who tend to have more fat naturally are endomorphs. According to nutritional scientist and bodybuilder Dr. Layne Norton, endomorphs need 13 to 14 calories per pound per day to maintain their weight, while ectomorphs can go slightly higher with 16 to 17 calories per pound.