Within the process of rapid weight loss (RWL)/rapid weight gain (RWG) to make weight for combat sports, there is always a trade-off between the advantages of being heavier than the opponent, and the disadvantages of impaired performance and potentially serious negative side effects.
21 competitive male (16) and female (5) Italian Muay Thai athletes underwent a supervised RWL/RWG protocol to observe changes in health markers and hormone concentrations. The protocol consisted of a 3-day RWL followed by an 8-hour rapid weight gain. The RWL intervention involved a 1000 Kcal/day deficit, with a macronutrient breakdown of 30g carbohydrate, 2kg/g BM protein and 0.5g/kg BM fat, along with potassium, omega 3, vitamin c, polyphenols, astaxanthin and cucumin supplementation. The goal of the intervention was to maximally deplete glycogen stores in an attempt to reduce fluid content. Training was kept to <2 hrs of low intensity exercise/day.
The average weight loss was 4.1% BM. During the RWL period there was a significant increase in blood glucose levels, total cholesterol and blood urea nitrogen (BUN). Creatitine was only increased in the male participants. There was a significant decrease in testosterone and thyroid-stimulating hormone (TSH).
The RWG protocol increased carbohydrate intake to 4.5g/kg, with 2 hourly intake of high-GI, calorie-dense meals. Fluid intake was set at 250ml every hour.
On average, the athletes regained 85% of the weight lost. Total cholesterol recovered to 87%, BUN to 90%, TSH to 71% Blood glucose and creatinine levels continued to rise, while testosterone levels continued to fall dramatically. Intracellular and extracellular fluid content failed to recover (although this was measured with bioimpedance, which has questionable validity for this purpose).
Despite being performed in a supervised and structured manner, with only a modest degree of weight loss, some health and hormonal markers showed poor recovery following rapid weight gain. These results should be viewed in the context of relevant weigh-in time (many combat sports will have a 24hr window) and the degree to which these markers may make a meaningful impact on performance.