The easy way to burn more calories even when you're not in the gym...

Almost everyone who exercises regularly knows they'll burn more calories in the gym than they will sitting in front of the television. What many people don't realize, however, is that your body continues to burn calories at a faster rate after you finish exercise.

Calories

Your consumption of oxygen, and hence the number of calories you burn, tends to rise after exercise. Although it used to be known as "oxygen debt," more recent studies have named it EPOC, which is short for excess post-exercise oxygen consumption.

The effect of EPOC on fat loss is a controversial topic. That's mainly because the duration of EPOC seems to vary so much from study to study. Some papers report that EPOC lasts for just one hour. Others have recorded EPOC lasting two days.

However, an Australian study, published by Jo Smith and Lars McNaughton, goes some way to explaining why some people burn more calories than others, even when they exercise in exactly the same way [5].

The trial, published in the European Journal of Applied Physiology, shows that the amount of muscle you have directly affects the length of EPOC.

Eight male and eight female physical education students took part in the study. Oxygen consumption was measured for several hours after exercise. Because the expenditure of calories and oxygen consumption are closely linked, the researchers were able to estimate how many calories were burned after exercise.

The men continued to burn more calories for almost 50 minutes after finishing the workout. But post-exercise calorie expenditure in women lasted for only 40 minutes.

When the figures were adjusted to take into account the fact that men have more muscle, variations between the males and females vanished. In other words, the more muscle you have, the more calories you burn after your workout.

One (but not the only) reason your body continues to burn more fat calories after intense exercise is because your body secretes more growth hormone.

Growth hormone is released in "pulses", which means levels rise and fall like the tides. A single surge in growth hormone increases both the number of fat calories your body burns for energy and your metabolic rate [2].

That's why growth hormone therapy often leads to a reduction in fat mass.

More interesting still, when people with a growth hormone deficiency have their growth hormone injections withdrawn, they tend to gain fat and lose muscle [1].

Women are often surprised to learn that their growth hormone levels are higher than those of men. Young women secrete roughly twice as much growth hormone at rest than their male counterparts. When they exercise, growth hormone levels peak more quickly in women than men [4].

It's also important to note that a diet containing insufficient calories can dramatically lower EPOC, reducing the number of fat calories you burn after exercise.

Some evidence for this comes from researchers at Hiroshima Women's University in Japan [7]. They studied a group of women who cycled for 60 minutes at 70% of VO2max the morning after two days on two different diets.

The first diet provided 1600 calories per day, while diet two provided only 800 calories per day.

EPOC was measured for seven hours after exercise. Following just two days of dietary restriction, EPOC was lowered by more than 50%.

The bottom line?

When you're losing weight, it's important to make sure you eat a diet that provides the correct number of calories, adequate amounts of protein, and the right mix of fats. This will help you lose fat while maintaining the muscle you've worked so hard to build.

References
1. Gibney, J., Healy, M.L., Stolinski, M., Bowes, S.B., Pentecost, C., Breen, L., McMillan, C., Russell-Jones, D.L., Sonksen, P.H., & Umpleby, A.M. (2003). Effect of growth hormone (GH) on glycerol and free fatty acid metabolism during exhaustive exercise in GH-deficient adults. Journal of Clinical Endocrinology and Metabolism, 88, 1792-1797
2. Gravholt, C.H., Schmitz, O., Simonsen, L., Bulow, J., Christiansen, J.S., & Moller, N. (1999). Effects of a physiological GH pulse on interstitial glycerol in abdominal and femoral adipose tissue. American Journal of Physiology, E277, 848-854
3. Pritzlaff, C.J., Wideman, L., Blumer, J., Jensen, M., Abbott, R.D., Gaesser, G.A., Veldhuis, J.D., & Weltman, A. (2000). Catecholamine release, growth hormone secretion, and energy expenditure during exercise vs. recovery in men. Journal of Applied Physiology, 89, 937-946
4. Pritzlaff-Roy, C.J., Widemen, L., Weltman, J.Y., Abbott, R., Gutgesell, M., Hartman, M.L., Veldhuis, J.D., & Weltman, A. (2002). Gender governs the relationship between exercise intensity and growth hormone release in young adults. Journal of Applied Physiology, 92, 2053-2060
5. Smith, J., & McNaughton, L. (1993). The effects of intensity of exercise on excess post-exercise oxygen consumption and energy expenditure in moderately trained men and women. European Journal of Applied Physiology, 67, 420-425
6. Kraemer, W.J., Volek, J.S., Clark, K.L., Gordon, S.E., Puhl, S.M., Koziris, L.P., McBride, J.M., Triplett-McBride, N.T., Putukian, M., Newton, R.U., Hakkinen, K., Bush, J.A., & Sebastianelli, W.J. (1999). Influence of exercise training on physiological and performance changes with weight loss in men. Medicine and Science in Sports and Exercise, 31, 1320-1329
7. Fukuba, Y., Yano, Y., Murakami, H., Kan, A., & Miura, A. (2000). The effect of dietary restriction and menstrual cycle on excess post-exercise oxygen consumption (EPOC) in young women. Clinical Physiology, 20, 165-169