Fasting may make it easier to stay in a caloric deficit, and therefore lose weight!
Chances are that you’ve heard of fasting or intermittent fasting in some way or another. The main principle is that you limit eating hours of the day, i.e. you put yourself in a fasted (catabolic) state for longer. As we are all about evidence based training we can´t just adopt anything and give it a try without reading up on the subject.
There are some limitations on current literature on fasting: different fasting procedures, training regimens, macro inclusions, populations (e.g. obese, young men, fit people, unfit people and so on) and short study durations. With that said, much can be extrapolated from the studies, but keep these things in mind before drawing conclusions.
This will be an introduction to fasting and we’ll dig deeper into the topic further on. For now, we can mention that data seems to show that some form of fasting is effective for reducing body weight, triglycerides and cholesterol in normal-weight, overweight and obese individuals! (1)
Study outcome
An RCT on young men performing resistance training for 8 weeks found that they reduced energy intake by 650 kcal per day on fasting days (4 days a week) although they had no caloric or food restriction. However, body composition after 8 weeks was the same as in the control group, exercising the same amount. Subjects in the fasting group thus probably compensated for their caloric deficit by eating more on non-fasting days. No strength or lean mass losses were seen in the fasting group, but the control group actually gained lean mass over the period (2).
Take home message: the strict eating window of fasting seems to make caloric restriction easier, but for results you may have to follow the protocol for more than 4 days a week.
Article by Jonas Liefke, 4rd year Medical Student, BSc Physiotherapy
Sources:
1. Grant m. Tinsley. Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition reviewsvr vol. 73(10):661–674 .
2. Grant m. Tinsley. Time-restricted feeding in young men performing resistance training: a randomized controlled trial. European journal of sport science, 2016
