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Be the tortoise or the hare: it doesn’t matter for fat loss

Interval training and moderate-intensity aerobic exercise can affect the body in different ways. But do these differences extend to fat loss?

Study under review: A systematic review and meta-analysis of interval training versus moderate-intensity continuous training on body adiposity


Rarely does the ERD cover a study that does not involve a nutrition or supplementation component. However, there are exceptions for studies that provide valuable information on related topics. The study under review is one such exception because it addresses whether interval training is more effective than steady-state cardio training for fat loss.

Exercise combined with diet modifications has been shown to be more effective[1] than either alone for promoting weight loss. Moreover, as seen in Figure 1, exercise has been identified[2] as a key player in long-term weight loss maintenance. Therefore, establishing exercise habits during the weight loss phase can help prevent weight regain and yo-yo dieting down the road. Yet, roughly 80% of adults in the U.S. do not currently meet the recommended physical activity guidelines from the CDC, which are the same recommendations made by the American College of Sports Medicine[3] (ACSM). One of the most common excuses[4] for lack of exercise is a lack of time.

The ACSM recommends that most adults engage in moderate-intensity cardiorespiratory exercise training for a minimum of 150 minutes per week, preferably through performing at least 30 minutes per day on at least five days per week. However, they state an alternative means to obtaining sufficient physical activity is to engage in vigorous-intensity cardiorespiratory exercise training for at least 75 minutes per week, preferably through performing at least 20 minutes per day on at least three days per week. Interval endurance training satisfies the vigorous-intensity requirement and has therefore been suggested to be a time-efficient alternative[5] to regular moderate-intensity steady-state cardio.

Numerous studies investigating the health effects of interval and steady-state cardiorespiratory training have been published, with some directly comparing the two. Previous meta-analyses have suggested that interval training might[6][7] produce superior improvements in cardiorespiratory fitness compared to steady-state cardio, and one large systematic review[8] suggested that higher training intensities, as would be observed with interval training, have a more favorable effect on body composition than lower training intensities common to steady-state. Yet, despite the time efficiency of interval training for promoting cardiorespiratory fitness, it remains unclear whether it is more efficient for fat loss.

The purpose of the study under review was to pool data from studies that have directly compared interval training to steady-state cardio training and use a meta-analysis to determine whether one method resulted in greater fat loss than the other.

About 80% of the U.S. population does not meet physical activity recommendations, with many people citing a perceived lack of time. However, exercise not only benefits changes in body composition when combined with a weight loss diet, but also plays a key role in long-term weight loss maintenance. Interval training has been proposed to be a time-efficient alternative to steady-state cardio for improving health and fitness. The study under review is a meta-analysis of studies directly comparing the two modalities for their ability to reduce fat mass.

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