What is the preferred type of exercise when dieting?
Dieting is often combined with aerobic exercise (i.e. cardio) with the aim to lose as much fat mass as possible. Resistance exercise is recommended to prevent some of the muscle mass loss that typically occurs during a diet. But what type of exercise, or combination, has the most beneficial impact on body composition during a diet?
This study investigated the effects of resistance training, aerobic training, and a combination of both on body composition while dieting in obese subjects.
Subjects were all put on the same diet plan providing an energy deficit of 500-700 kcal per day. The subjects trained 3 times per week, but were divided into 3 different training groups:
- 60 min of aerobic training
- 60 min of resistance training,
- 75-90 min of combined aerobic and resistance exercise training.
All groups lost around the same amount of weight over the 6-month period (~9 kg). However, muscle mass loss was less in resistance exercise (-1.7 kg) and combined exercise group (-1.0 kg) when compared to the aerobic exercise group (-2.7 kg).
While not statistically significantly different, fat loss appeared to be greatest in the resistance exercise group (-7.3 kg), followed by the combined group (-7.0 kg), and the least in the aerobic exercise group (-6.3 kg).
As to be expected, these data show that incorporating resistance exercise can reduce muscle mass loss while dieting. But perhaps surprisingly, resistance training appears to result in the same, if not more, fat mass loss when compared to aerobic exercise.
A major strength of this study was the relatively large number of subjects and long study duration. In conclusion, resistance training appears to be the preferred type of exercise to improve body composition during a diet.
Study:
Villareal et al, Aerobic or Resistance Exercise, or Both, in Dieting Obese Older Adults. New Eng J Med, 2017
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In regard to body composition, it is true that resistance training seems to be the best option because it minimizes muscle loss during dieting. However, because the combined intervention improves cardiovascular health to the same extend as aerobic exercise only, isn’t that a better approach to overall health? Imo, the article shares this point of view.
Furthemore, what would you expect in 1) young, obsese adults and 2) young, overweight adults or 3) when subjects are in energy balance ?
Hey Lucas, yes for overall health I would say a combination of resistance and aerobic exercise is best. But if you have to pick either resistance or aerobic exercise, I would pick resistance exercise.
I think the conclusions would be the same in other populations. Just the numbers would be different. For example, in energy balance, resistance would still be more beneficial for muscle mass, but subjects would build instead of loose muscle.