The Science Behind Weight Loss and Exercise

Weight loss and gain is a balancing act between energy consumed by the body and energy expenditure. Exercise is the most variable factor in human energy expenditure in that this is what we have control over most. While we are exercising we are expending energy, however what is less known is that following a bout of exercise, our body continues to expend energy or ‘burn calories’ at a higher rate than normal. The rate at which your body burns calories at resting (homeostasis) will heavily influence your weight loss.

weight loss and exerciseIn our Daily Lives, Energy Expenditure Falls Under 3 Categories:

Basal Metabolic Rate – Even when you are not exercising, your body requires energy to maintain processes such as breathing, pumping blood around your body, cellular activity and adjusting hormone levels. Our basal metabolic rate accounts for roughly 70% of our daily energy expenditure and depends on our body size, sex, and age.

Thermogenic Effect of Food – The digestion, absorption and storage of food also requires energy. Different foods require different amounts of energy to be digested and absorbed. The vegetable Broccoli for example, requires more energy from the body to digest and absorb than contains therefore actually contributes to energy expenditure and not energy consumption.

Physical Activity – Regardless of whether aerobic or resistance exercise, physical activity involves muscle contractions. Our muscles require energy in order to contract and relax and this energy comes from oxygen. So when we exercise, our energy demands increase, so we breathe more to increase our oxygen supply. Processes like increasing ventilation, blood flow to muscles and increased hormone production all result in additional energy expended.

For the most part, energy expenditure from our basal metabolic rate and the thermogenic effect of food remain relatively constant so therefore, physical activity is the variable that we have most control over.  Following a bout of exercise, the effects of the exercise are still being felt by the body and our oxygen consumption remains elevated for a period. This means, even though we have finished exercising, we are still burning calories at an elevated rate thus our metabolism is raised for a certain time.

Types of Exercise and Weight Loss

Types of Exercise – Research has shown that post exercise oxygen consumption is elevated following both aerobic and resistance exercise. Since it is difficult to compare the two activities, limited research exists on this topic. Burleson and colleagues (1998) were one such group to accomplish this and demonstrated that resistance exercise was superior to aerobic in increasing post exercise caloric expenditure.

Duration – A study by Norwegian researchers Bahr and colleagues (1987) found a linear relationship between exercise duration and the magnitude of post exercise oxygen consumption. Participants exercised for either 20, 40 or 80 minutes at a set intensity and oxygen consumption was elevated 32% for 40 minutes compared to 20 minutes and elevated 187% for 80 minutes compared to 20 minutes. This doesn’t mean that you must exercise for 80 minutes, it shows that longer durations of exercise result in a greater oxygen consumption post exercise and more calories burned.

Intensity – Another study by Bahr and colleagues (1991) exercised individuals for 80 minutes at different intensities (30%, 50% and 75% of VO2 max) and found that the 75% group had the greatest “Excess Post-Exercise Oxygen Consumption” (EPOC), resulting in 150 calories burned after exercise had ceased. Now you don’t need to exercise for 80 minutes to increase post exercise calories burned. Another study by Larson and colleagues (2014) demonstrated this by exercising individuals with health conditions such as overweight/obesity, high blood pressure and high cholesterol for either 1 x 4 min (85% HR max), 4 x4 min (85% HR max) and 50 min at 70% HR max. The high intensity training proved more effective for increasing post exercise oxygen consumption than lower intensity continuous exercise.

What Does all This Mean?

Both resistance and aerobic training will induce post exercise caloric expenditure and so is one of the reasons that both should be included regularly in an exercise plan for weight loss. Exercise intensity and duration are two variables that can be manipulated to increase EPOC. Usually longer duration workouts with lower intensities has its benefits but for many people who need to fit their exercise into their busy day, long workouts may not be possible. Shorter duration workouts with higher intensities can be even more effective and also increase calories burned post exercise.

If you’d like further information on weight loss and exercise, speak to one of our practitioners today (02) 9588 7000 or book online at


Larsen, I., Welde, B., Martins, C., & Tjønna, A. E. (2014). High‐and moderate‐intensity aerobic exercise and excess post‐exercise oxygen consumption in men with metabolic syndrome. Scandinavian Journal of Medicine & Science in Sports, 24(3), e174-e179. doi:10.1111/sms.12132

Bahr, R., & Sejersted, O. M. (1991). Effect of intensity of exercise on excess postexercise O2 consumption. Metabolism: Clinical and Experimental, 40(8), 836-841. doi:10.1016/0026-0495(91)90012-

L Burleson, J., M A, O’Bryant, H. S., Stone, M. H., Collins, M. A., & Triplett-McBride, T. (1998). Effect of weight training exercise and treadmill exercise on post-exercise oxygen consumption. Medicine and Science in Sports and Exercise, 30(4), 518-522. doi:10.1097/00005768-199804000-00008

Bahr, R., Ingnes, I., Vaage, O., Sejersted, O. M., & Newsholme, E. A. (1987). Effect of duration of exercise on excess postexercise O2 consumption. Journal of Applied Physiology, 62(2), 485-490. Tips to Increase Your Calorie Expenditure for Weight Loss inherit closed closed 3613-revision-v1 2018-09-04 17:25:03 2018-09-04 07:25:03 3613

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