BRIEF REVIEW – Weight Cutting in Muay Thai


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. 

  1. Cannataro R, Cione E, Gallelli L, Marzullo N, Bonilla DA. Acute Effects of Supervised Making Weight on Health Markers, Hormones and Body Composition in Muay Thai Fighters. Sports. 2020;8(10):137.

About the author

Sam Gilbert

Sam Gilbert is a registered physiotherapist with the Australian Physiotherapy Association (APA) and certified strength and conditioning specialist (CSCS) with the National Strength and Conditioning Association (NSCA). He holds a bachelor’s degree in Physiotherapy from Latrobe university (Melbourne, Australia) and a master’s degree in Exercise Science (Strength and Conditioning) from Edith Cowan University (Perth, Australia).

A 3rd Dan black belt in Shinkyokushinkai Karate under the World Karate Organisation (WKO), Sam participated for over 20 years in full contact competition, winning multiple state and national titles, and culminating in a 4th place in the heavyweight division of the Shinkyokushinkai World Cup in 2009.

As the co-founder and clinical director of Club 360, the premier multi-disciplinary health and fitness center in Tokyo, Japan, Sam has combined his practical experience with an in-depth study of sports performance in relation to combat sports, and strives to help other combat athletes reach their full competitive potential, whilst at the same time decreasing injury risk and increasing competition and training potential.

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By Sam Gilbert