The effect of an 8-week low carbohydrate high fat diet on maximal strength performance, body composition and diet acceptability in sub-elite Olympic weightlifters and powerlifters

摘要

In the current sports nutrition literature there is a lack of insight into the weight loss procedures for weight-restricted power and strength athletes (e.g. Olympic weightlifters and powerlifters). Broadly speaking, methods of rapid weight loss such as severe caloric restriction, dehydration, purging, sauna sessions and the use of laxatives are still practiced, with only a few athletes leaning towards safer, more gradual weight loss practices. In addition to the health concerns associated with rapid weight loss methods, there is also a performance element, as rapid weight-loss schemes have been associated with significant decrements in strength performance, whereas longer gradual weight loss will preserve or allow for an increase in strength performance (Garthe, Raastad, Refsnes, Koivisto, & Sundgot-Borgen, 2011). Most gradual approaches involve the reduction of calories, which primarily comes from a reduction in fat as fat is very calorie dense. There is a ‘best practice’ approach which works for many athletes, but it is often associated with feeling hungry. An alternative approach for athletes who experience hunger issues could be a low carbohydrate high fat (LCHF) diet, whereby a desired weight loss can be achieved through a spontaneous reduction in calories from an increase in satiety. As a disparity exists between the current literature and the various weight loss strategies used by competitive athletes, the question still exists regarding the optimal method for weight loss in competitive strength and power athletes. Instead of drastically reducing calories or sweating away all undesired bodyweight, a simple change in switching from a carbohydrate-dominant diet to a fat-dominant diet could be a worthwhile option to consider in order to increase the satiety of the weight-loss diet. Previous research has reported a spontaneous calorie reduction can occur during an LCHF diet, reducing bodyweight, while strength and power performance is maintained (Paoli et al., 2012; Sawyer et al., 2013b). An LCHF diet is where there is an extreme restriction of carbohydrate-based foods (50-130 g.kg.day) and an unlimited consumption of fat and protein (Feinman et al., 2015). However, there has only been limited research in this area and many questions still remain regarding its suitability to the energy demands of anaerobic-based sports and whether such diets can be adhered to by these athletes. Therefore, more comprehensive research is needed to investigate the application of such a diet and if it has any benefit for strength and power performance.Thus, my research design will help to quantify what effects an 8-week LCHF diet (1.0g.kg.day) has on relative and absolute strength performance, anthropometrics and diet acceptability in sub-elite Olympic weightlifters and powerlifters. The aim of this study is to determine if both strength performance and lean muscle mass can be maintained while losing undesirable bodyweight. In addition, through qualitative measures of what the athletes are experiencing during the diet, the study will determine if the diet is appropriate for this particular cohort.