Novel methods of acute weight loss practiced by combat sport athletes include ‘water loading’; the consumption of large fluid volumes for several days prior to restriction. We examined claims this technique increases total body water losses, while also assessing the risk of hyponatremia. Male athletes were separated into control (CON, n=10) and water loading (WL, n=11) groups and fed a standardised energy-matched diet for 6 days. Day 1-3 fluid intake was 40 mL. kg-1 and 100 mL. kg-1 for CON and WL, respectively with both groups consuming 15 mL. kg-1on Day 4 and following the same rehydration protocol on Days 5-6. We tracked body mass (BM), urine sodium, specific gravity (USG) and volume, training-related sweat losses and blood concentratio...