Plain language summary
A global rise in overweight and obesity has created uncertainty around the efficacy of current nutritional guidelines that favour a high-carbohydrate, low-fat (HCLF) diet. Evidence has shown a low-carbohydrate, high-fat (LCHF) diet, compared with a HCLF diet, is at least as effective in reducing body weight and waist circumference and is more effective for improving metabolic health. The aim of this study was evaluate changes in weight and metabolic health between these two dietary approaches among 26 overweight and obese defence force personnel. Participants were randomly allocated to a HCLF or LCHF diet for 12 weeks. Weight, waist circumference, fasting lipids and glycaemic markers were assessed at baseline and 12 weeks. Both study groups demonstrated a significant reduction in weight and waist circumference, and the LCHF group showed further improvements in metabolic markers. Based on these results, the authors conclude a high-fat dietary approach shows promise for short-term weight loss and improved metabolic health compared with current dietary guidelines among the defence force population.
Abstract
Overweight, obesity, and poor health is becoming a global concern for defence force personnel. Conventional nutrition guidelines are being questioned for their efficacy in achieving optimal body composition and long-term health. This study compared the effects of a 12-week low-carbohydrate, high-fat diet with a conventional, high-carbohydrate, low-fat diet on weight reduction and metabolic health outcomes in at-risk New Zealand Defence Force personnel. In this randomised controlled trial, 41 overweight personnel were assigned to intervention and control groups. Weight, waist circumference, fasting lipids, and glycaemic control were assessed at baseline and at 12 weeks. Within-group change scores were analysed using the t statistic and interpreted using a p < 0.05 level of statistical significance. Between-group mean differences and confidence intervals were analysed using effect sizes and magnitude-based inferences. Twenty-six participants completed the trial (14 intervention, 12 control). Both groups showed statistically significant weight and waist circumference reductions; the intervention group significantly reduced triglycerides and serum glucose and significantly increased high-density lipoprotein cholesterol (HDLc). Relative to control, the intervention group showed small, possibly to likely beneficial effects for weight, triglycerides, glucose, insulin, and homeostasis model assessment of insulin resistance; moderate, likely beneficial effects for HDL cholesterol, triglyceride:HDLc ratio and HbA1c; and a small, likely harmful effect for low-density lipoprotein cholesterol. This dietary approach shows promise for short-term weight loss and improved metabolic health outcomes conditions compared with mainstream recommendations. It should be offered to defence force personnel at least as a viable alternative means to manage their weight and health.
Methodological quality
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