Sara Hayward conducted a research study bent towards observing intermittent fasting’s effect on “markers of body composition and mood state.” The experiment was recorded in the Journal of the International Society of Sports Nutrition. It was published in 2014, on December 1.

Hayward continually stressed the fact that “Optimal athletic performance is often linked to body composition, therefore depending on the sport and position, a decrease in body fat would lean toward an increase in athletic fitness.” Fair enough, right?

Hayward continued her rant by making the point that intermittent fasting has been shown and proven as a way to decrease body fat while maintaining muscle mass. “The purpose of this study,” says Hayward, “is to investigate the effects of intermittent fasting and resistance training on body composition, mood state, and resting energy expenditure.”

Here is how the study went…

8 males and 16 females (a total of 24), all of which were volunteers, were randomly assigned 1 of 3 groups. The 3 contrasting groups consisted of:

1. Resistance Training only (RT). In this group, participants performed 4 upper and lower body split workouts a week.

2. Intermittent Fasting only (IMF). Participants in this group were subjected to only consuming calories in an 8-hour window, but were allowed to maintain normal and free-living activity.

3. Intermittent Fasting plus Resistance Training (IMFRT), “this group participated in 4 workouts per week as well as only ingesting calories within the 8-hour window.”

The participants were required to complete baseline testing, which consisted of Resting Energy Expenditure on a TrueOne ParvoMedics metabolic cart in order to discern the participant’s caloric needs, as well as measuring the body composition with a dual-energy x-ray absorptiometry scan (DEXA).

For the thirty days following this, participants followed the protocol that their group was under. They came in on day fifteen for a weigh-in and a questionnaire designed to test the person’s mood state.

The final test session was conducted after the thirty-day workout and/or dietary restriction. “Data analysis was performed using a MANCOVA [3(group)x2(time) gender as a covariate], as well as Independent Sample T-Test to determine individual group differences, post hoc set was set at p<0.05.”

It was discovered that the group undergoing the Intermittent Fasting plus Resistance Training experienced a decrease in fat mass and weight when compared to the Resistance Training only group.

However, no difference was detected between the Resistance Training only group and the Intermittent Fasting group, which suggested that intermittent fasting alone may not be any more effective in decreasing body fat percentage than resistance training.

Sara Hayward concludes her experiment by sharing the observation that when intermittent fasting is “paired” with resistance training, lean mass is easily “retained” and/or “enhanced” while “decreasing body fat, thus enhancing body composition.”

For further reading check out: Fasting For Depression


Bibliography:

  1. Sara Hayward, et al. “Effects of Intermittent Fasting on Markers of Body Composition and Mood State.” Journal of the International Society of Sports Nutrition, BioMed Central, 1 Dec. 2014, jissn.biomedcentral.com/articles/10.1186/1550-2783-11-S1-P25.