The effect of a 12-week low glycaemic index diet on heart disease risk factors and 24 h glycaemic response in healthy middle-aged volunteers at risk of heart disease: a pilot study

Abstract

Objective: To compare the effects of two energy-restricted healthy diets, one with a low GI and one with a high GI, on heart disease risk factors and weight loss in subjects at risk of heart disease. Design: A 12-week randomized parallel study of low and high GI, healthy eating diets was carried out. Setting: The study was carried out at the Hammersmith Hospital. Subjects: Eighteen subjects were recruited by advertisement and randomized to one of the two diets. Fourteen completed the study but one was excluded from the final analysis. Methods: At randomization, subjects were advised to follow the intervention diet for 12 weeks. Before randomization and on completion of the study, anthropometrics, fasting cholesterol and glucose blood tests and 24-h glucose measurements were taken using a continuous glucose monitoring system (CGMS). Statistical analysis was carried out using non-parametric tests. Median (IQR) are presented. Results: A significantly different dietary GI was achieved in the low GI (median: 51.3 (IQR: 51.0-52.0) compared to the high GI (59.3 (59.2-64.0) (P ¼ 0.032) group. By week 12, both groups reduced their energy intake by: low GI group: À 167 ( À 312-À 123) kcal/day (P ¼ 0018) vs high GI group: -596 ( À 625-À 516) (P ¼ 0.018) kcal/day, the difference between the groups being significant (P ¼ 0.010). However, only the low GI group lost weight ( À 4.0 ( À 4.4-À 2.4) kg (P ¼ 0.018) whereas the high GI group did not significantly change in weight ( À 1.5 ( À 3.6-0.8) kg (P ¼ 0.463). By week 12, the low GI group also had a significantly lower 24-h area under the curve (AUC) (7556 (7315-8434) vs 8841 (8424-8846) mmol-h/l (P ¼ 0.045) and overnight AUC (2429AUC ( (2423AUC ( -2714 vs 3000 (2805-3072) mmol-h/l (P ¼ 0.006) glucose as measured by CGMS. There were no differences in the other heart disease risk factors assessed. Conclusions: This pilot study provides some evidence that consuming a low GI diet in addition to weight loss and healthy eating may reduce cardiovascular risk. Other potential benefits of GI might have been masked by weight loss in the low GI group. Larger-scale studies need to follow.

Exercise Training and Dietary Glycemic Load May Have Synergistic Effects on Insulin Resistance in Older Obese Adults

“…However, this does not take into account that the metabolic response varies substantially between carbohydrates, as evidenced by different glycemic and insulinemic responses [3] . Diets that include carbohydrates with a low-glycemic response result in lower glucose and lipid levels when compared to high-glycemic diets [8,36,37] . While there are no long-term clinical trials examining the effects of high-or low-glycemic diets on insulin resistance or obesity in the elderly, two small clinical trials report greater weight loss utilizing a low-glycemic approach [8,38] .…”

“…Diets that include carbohydrates with a low-glycemic response result in lower glucose and lipid levels when compared to high-glycemic diets [8,36,37] . While there are no long-term clinical trials examining the effects of high-or low-glycemic diets on insulin resistance or obesity in the elderly, two small clinical trials report greater weight loss utilizing a low-glycemic approach [8,38] . Studies conducted by our group observed improvements in insulin and glucose metabolism in insulin-resistant cirrhotic patients after a low-glycemic diet [39] .…”

“…Frost et al [5] performed a 3-week randomized trial using high-and low-glycemic diets in young women with a family history of coronary heart disease; insulin sensitivity was increased on the low-glycemic diet and decreased on the high-glycemic diet. A recent study by Philippou et al [8] provided energy-restricted high-and low-glycemic diets to overweight/obese volunteers for 12 weeks and found that weight loss and glucose metabolism were more favorably improved following the low-glycemic diet. To date, there are no comprehensive studies on the effects of more prolonged high-or low-glycemic diets on insulin resistance in older obese adults.…”

Macronutrients and type 1 diabetes (revision number 6)

“…Ten randomised controlled trials were identified that presented evidence on GI in relation to fasting blood lipid concentration, all of which were included in a meta-analysis (Wolever & Mehling, 2003;Raatz et al, 2005;McMillan-Price et al, 2006;Bellisle et al, 2007;Sichieri et al, 2007;Abete et al, 2008;Jensen et al, 2008;Philippou et al, 2008;Philippou et al, 2009a;Philippou et al, 2009b). Two trials were subsequently identified in the update search Gogebakan et al, 2011) 10.16.…”

“…Four randomised controlled trials were identified that presented evidence on GI in relation to the ratio of fasting total cholesterol:HDL-cholesterol ratio, all of which were included in a meta-analysis (McMillan-Price et al, 2006;Bellisle et al, 2007;Philippou et al, 2008;Philippou et al, 2009b) Glycaemic index and fasting non-esterified fatty acid concentration…”