I was recently discussing a published case study on my last bodybuilding contest prep [1] with some of my professors. During this discussion, the topic of refeed days came up. I mentioned the proposed benefits of refeed days: keeping metabolic rate elevated, improving workout performance, increasing muscle retention while dieting, and providing a mental break to help prevent binging, and was asked if I had any scientific evidence to back up these claims. I didn’t have a great answer. From an applied standpoint, I knew a majority of successful bodybuilders do not eat the same macronutrient distribution daily while dieting for a contest and most incorporate things like: carb cycling, refeed days, cheat meals, cheat days, etc. This approach is even something most individuals who use a science-based approach and broscientists would agree on. Therefore, I assumed there had to be something to it or it wouldn’t be so widely incorporated into bodybuilding contest prep plans. However, I was not sure if this was another example of an approach that bodybuilders use that science hasn’t caught up to or if there was science to support this practice so I decided to dig into the scientific literature and see what I could find. What follows is a summary of peer-reviewed scientific literature related to refeeding.

 

Metabolic Rate/Fat Loss:

Many individuals incorporate refeed days while dieting in an attempt to keep metabolic rate elevated. This rationale for this is centered on leptin, a hormone secreted from fat cells [2]. Reductions in fat cell size or energy intake (both of which happen while dieting) decrease leptin secretion [3]. In obese individuals, reductions in plasma leptin concentrations of 36% in 4 days [4] and 54% in 1 week [5] of energy restriction have been observed. Leptin levels in bodybuilders during contest prep are lower than those observed in obese participants. A recent case study following a professional natural bodybuilder during a 6 month contest preparation observed leptin levels below the normal range (3.7 – 11.1 ng/ml) at the start of contest preparation which were further decreased to 1.36 ng/ml by the end of contest preparation [6].

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