How Long Does it Take to Burn Calories

The time it takes to burn off calories from the food you eat depends mainly on three factors: how many calories there are in the food, how much you weigh, and what type of activity you do. The more calories you consume, the longer you have to workout to burn those calories. Doing high-intensity activities makes your body use up calories faster than doing low-intensity activities. And interestingly, the less you weigh, the longer it takes to burn off calories from food, all other factors being equal.

A person's general health, percent body fat, and genetics also determine how quickly calories are burned. Even if two people have the same weight, eat the same food, and do the same activity, one person may have to work longer to expend all the calories.

The approximate formula for how long it takes to burn calories is

M = C/(WA)

where M is minutes, C is the number of calories ingested, W is your weight in pounds, and A is a number that corresponds to the intensity level of your activity. The equivalent formula for weight in kilograms is

M = C/(2.205WA)

The value of A depends on the exercise or activity you do. For example, sleeping and watching TV have very low values, between 0.005 and 0.01. The activity values for walking are between 0.03 and 0.07, while the values for running are between 0.05 and 0.13 depending on your speed. As it turns out, power-walking at speeds of 5 mph or greater will actually burn calories faster than running at the same speed. (Walking is more difficult at faster speeds, so it burns more calories.) Weight-lifting and intense cardio can have values of 0.1 and greater.

The two keys to losing weight are consuming fewer calories and expending more energy. If you consistently eat more calories than you can burn in a day, you will gain weight. If you burn more calories than you eat, you will lose weight.

© Had2Know 2010