When you exercise at a moderate-intensity, you don’t get the “after-burn” effect you get with a high-intensity exercise where you burn calories at a higher rate for hours after you finish. You may burn calories at a faster rate for, at most, an hour after moderate-intensity endurance exercise. What about the longer term? Is there any evidence that regular endurance exercise increases your resting metabolic rate and gives you a metabolic advantage?
Metabolism Overview
As you may know, your resting metabolic rate is the number of calories your body burns each day just to maintain normal bodily functions. When you’re “off duty,” your body still works overtime. Even as you sleep, your body is never truly really at rest since cells in your body, especially your brain, require a constant energy supply. Your resting metabolic rate makes up between 60 and 80% of the calories you burn each day, just to maintain homeostasis.
The other two components that make up your metabolic rate is the thermal effect of food, the calories your body uses to break down and absorb the foods you eat, and the calories you burn during exercise. The thermal effect of food accounts for 5 to 10% of the calories burned each day and exercise between 20 and 30% of your total daily energy expenditure.
What impact does endurance exercise have on this? Does it raise your resting metabolic rate when you do it long term?
The Effect of Endurance Exercise on Metabolic Rate
As mentioned, high-intensity exercise increases your metabolic rate after a workout because your body has to expend more energy during recovery. This effect is minimal after moderate-intensity exercise where you recovery more quickly. What about the longer term?
Most research shows that regular endurance training doesn’t increase resting metabolic rate or total energy expenditure even when you train over a long period of time. A study published in the Journal of Clinical Endocrinology and Metabolism showed that young, healthy women who took part in a six-month endurance training program had greater aerobic capacity at the end of the study but had no change in their total daily energy expenditure as a result of training. Not only did training not increase their resting metabolic rate, but they also didn’t burn more total calories for the day.
How can you explain this? Based on some research, people who do endurance exercise compensate for the calories they burn by moving around less when they aren’t actively exercising.
Another study published in the American Journal of Clinical Nutrition came to a similar conclusion. Seventy-four men and women took part in a 5-month endurance training program. By the end of their training, their aerobic capacity had improved as much as 18%. They also experienced some fat loss, but their resting metabolic rate remained unchanged when measured 24 and 72 hours after training.
In still another study, adults who endurance trained for a year showed no change in their resting metabolic rate, although they did lose body fat and increased the maximum amount of fat they oxidized during exercise. This means they were better able to use fat as an energy source during exercise due to training, although there were no changes in fat oxidation at rest.
What about Resistance Training?
Based on one study, resistance training combined with green tea was effective for boosting resting metabolic rate. Participants in this study showed an increase in resting metabolic rate, decreased waist measurement, a decline in body fat and an increase in lean body mass. Another study showed that resistance training increased resting metabolic rate in older adults. This makes sense since resistance training increases lean body mass so you burn more calories at rest.
The Bottom Line?
Most research shows endurance exercise doesn’t increase resting metabolic rate longe term. If you do high-intensity exercise, you’ll benefit from the after-burn effect but even high-intensity exercise doesn’t increase your metabolic rate once you’ve recovered from a workout. If you do long periods of endurance exercise without adequate calories, it may actually reduce your resting metabolic rate as your body adapts to a calorie deficit. Long endurance training sessions can also increase cortisol levels, making it more difficult to control your weight.
On the other hand, resistance training may modestly boost your resting metabolic rate when you use enough resistance to build muscle. If you want to burn more calories even at rest, resistance training using a weight that’s challenging enough to damage muscle fibers and stimulate growth is the best option. Endurance training may improve the health of your heart but it doesn’t boost your metabolism at rest.
References:
The Journal of Clinical Endocrinology and Metabolism. Vol. 87, No. 3. 1004-1009. (2002)
Am. J. Clin. Nutr. 68(1): 66-71. (1998)
Int. J. Sports Med. 2010 Jul; 31(7): 498-502.
Cardoso GA, et al. J Med Food. 2012 Nov 9.
J Appl Physiol. 2000;89(3):977-84.
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