Journal Article

Low-Fat Versus Low-Carbohydrate Weight Reduction Diets: Effects on Weight Loss, Insulin Resistance, and Cardiovascular Risk: A Randomized Control Trial

MCKINLEY, Michelle C, BRADLEY, Una, BELL, Patrick M, HUNTER, Steven J, COURTNEY, C. Hamish, ENNIS, Cieran N, YOUNG, Ian S, MCCANCE, David R, MCENENY, Jane, SPENCE, Michelle

2009

Overview

Low-fat hypocaloric diets reduce insulin resistance and prevent type 2 diabetes in those at risk. Low-carbohydrate, high-fat diets are advocated as an alternative, but reciprocal increases in dietary fat may have detrimental effects on insulin resistance and offset the benefits of weight reduction. We investigated a low-fat (20% fat, 60% carbohydrate) versus a low-carbohydrate (60% fat, 20% carbohydrate) weight reduction diet in 24 overweight/obese subjects ([mean +/- SD] BMI 33.6 +/- 3.7 kg/m(2), aged 39 +/- 10 years) in an 8-week randomized controlled trial. All food was weighed and distributed, and intake was calculated to produce a 500 kcal/day energy deficit. Insulin action was assessed by the euglycemic clamp and insulin secretion by meal tolerance test. Body composition, adipokine levels, and vascular compliance by pulse-wave analysis were also measured. Significant weight loss occurred in both groups (P < 0.01), with no difference between groups (P = 0.40). Peripheral glucose uptake increased, but there was no difference between groups (P = 0.28), and suppression of endogenous glucose production was also similar between groups. Meal tolerance-related insulin secretion decreased with weight loss with no difference between groups (P = 0.71). The change in overall systemic arterial stiffness was, however, significantly different between diets (P = 0.04); this reflected a significant decrease in augmentation index following the low-fat diet, compared with a nonsignificant increase within the low-carbohydrate group. This study demonstrates comparable effects on insulin resistance of low-fat and low-carbohydrate diets independent of macronutrient content. The difference in augmentation index may imply a negative effect of low-carbohydrate diets on vascular risk.

• Publisher: American Diabetes Association
• Subject: Adult / Biological and medical sciences / Body composition / Body fat / Carbohydrates / Cardiovascular Diseases - etiology / Cardiovascular Diseases - prevention & control / Clinical trials / Comparative analysis / Diabetes / Diabetes. Impaired glucose tolerance / Diet / Diet, Carbohydrate-Restricted / Diet, Fat-Restricted / Diet, Reducing - methods / Dietary Carbohydrates - administration & dosage / Dietary Fats - administration & dosage / Endocrine pancreas. Apud cells (diseases) / Endocrinopathies / Energy / Energy Intake / Etiopathogenesis. Screening. Investigations. Target tissue resistance / Exercise / Female / Glucose / Glucose Clamp Technique / Health aspects / Humans / Insulin Resistance / Lifestyles / Low carbohydrate diet / Low fat diet / Male / Medical sciences / Middle Aged / Obesity / Original / Overweight / Physiological aspects / Prevention / Research design / Risk Factors / Type 2 diabetes / Vascular Resistance / Weight control / Weight Loss