Based on research collected in 2017 by IMMAF volunteer Ben Crighton and fellow researchers, the group’s latest case study was published in the International Journal of Sport Nutrition and Exercise Metabolism, documenting performance effects and harmful consequences through the ‘physiological and metabolic impact of extreme weight cutting by an elite male MMA athlete.’ Ben Crighton MSc is a performance nutritionist and PhD researcher in mixed martial arts, who has produced multiple studies with credited colleagues and medical specialists from Liverpool John Moores University. Abstract: The aim of the present case study was to quantify the physiological and metabolic impact of extreme weight cutting by an elite male MMA athlete. Throughout an 8-week period, we obtained regular assessments of body composition, resting metabolic rate (RMR), VO2peak and blood clinical chemistry to assess endocrine status, lipid profiles, hydration and kidney function. The athlete adhered to a “phased” weight loss plan consisting of 7 weeks of reduced energy (ranging from 1300 – 1900 kcal.d-1) intake (phase 1), 5 days of water loading with 8 L per day for 4 days followed by 250 ml on day 5 (phase 2), 20 h fasting and dehydration (phase 3) and 32 h of rehydration and refuelling prior to competition (phase 4). Body mass declined by 18.1 % (80.2 to 65.7 kg) corresponding to changes of 4.4, 2.8 and 7.3 kg in phase 1, 2 and 3, respectively. We observed clear indices of relative energy deficiency, as evidenced by reduced RMR (-331 kcal), inability to complete performance tests, alterations to endocrine hormones (testosterone: ❤ nmol.L-1) and hypercholesterolemia (>6 mmol.L-1). Moreover, severe dehydration (reducing body mass by 9.3%) in the final 24 hours prior to weigh-in induced hypernatremia (plasma sodium: 148 mmol.L-1) and acute kidney injury (serum creatinine: 177 μmol.L-1). These data therefore support publicised reports of the harmful (and potentially fatal) effects of extreme weight cutting in MMA athletes and represent a call for action to governing bodies to safeguard the welfare of MMA athletes. Affiliations: 1Research Institute for Sport and Exercise Sciences. Liverpool John Moores University, Liverpool, UK. 2Pure Sports Medicine, London, UK. 3Department of Nephrology, Royal Liverpool University Hospital, Liverpool, UK. *Address for Correspondence: Dr. James P. Morton, Research Institute for Sport and Exercise Sciences Liverpool John Moores University Byrom Street, Liverpool, L3 3AF, UK Email: J.P.Morton@ljmu.ac.uk Full study available HERE. Ben frequently volunteers in event operations at IMMAF championships where he also delivers educational seminars, in addition to collecting weight cutting and performance data from international amateur MMA athletes. Previous research from Liverpool John Moores University was highlighted by IMMAF.org via the British Journal of Sports Medicine in 2015, shortly after the tragic death of professional Chinese flyweight Yang Jiang Bing, who was reported to have shockingly passed away as a result of weight cutting complications. The editorial and study concluded in a Call for Action. Click HERE for the full article and PDF download.