Abstract
As the obesity epidemic continues unabated, further investigation of novel weight loss approaches is warranted. Low carbohydrate diets (LCDs) provide one possible dietary strategy for weight loss. This thesis addresses continuing concerns regarding this weight loss approach by comphrensively investigating LCDs. The effects of a LCD, with and without exercise, on CVD risk factors was investigated in a 6 month randomised study. Fifty-six overweight or obese men were instructed to follow a LCD whilst either increasing or maintaining baseline activity levels (Chapter 3). Results demonstrated LCDs to be a safe and effective weight loss strategy with no significant additive effects of exercise seen. Low levels of compliance to exercise instructions were evident therefore subjects were regrouped according to reported exercise levels (Chapter 4). An additive effect on the reduction of weight, body fat mass, diastolic blood pressure, glycaemic response and C-reactive protein (CRP) was seen in subjects who reported increasing activity levels. In order to elucidate the nature and extent of the rapid initial weight loss associated with LCDs a second study investigated the early changes in weight and body composition (Chapter 5). Overweight or obese women (n=17) followed a LCD for 8 weeks with rapid initial weight loss observed and body fat reduced from the outset. Finally, a systematic review with a meta-analysis was conducted to assess the current evidence investigating the efficacy and CVD risk of reduced carbohydrate diets with exercise as a weight loss intervention (Chapter 6). No significant added effect of exercise on weight loss or CVD risk reduction was seen. This evidence demonstrates that LCDs are an effective means of reducing adiposity and inducing positive effects across numerous CVD risk factors. Regular but modest amounts of exercise may induce additional positive effects on weight and CVD risk. Therefore a whole lifestyle approach incorporating a LCD with exercise is an efficacious alternative to more conventional weight loss strategies.