Low-GI diets not superior to high-GI diets for weight loss and obesity prevention: Study
USA: Scientists in a new study published in the journal Advances in Nutrition disapproved the myth that consuming high-glycemic foods, such as white bread or soft drinks, is more likely to result in weight gain and promote fat storage, and increase obesity risk.
The study found that the consumption of high-glycemic foods, otherwise known as "fast carbs," do not lead to more weight gain than eating low-glycemic foods.
"There is scant scientific evidence that low-GI diets are superior to high-GI diets for weight loss and obesity prevention," the authors write.
High-glycemic index (high-GI) foods have been hypothesized to promote fat storage and increase obesity risk. Glenn A Gaesser, College of Health Solutions, Arizona State University, Phoenix, AZ, USA, and colleagues searched the online databases for observational studies reporting an association between BMI and dietary GI, and for meta-analyses of randomized controlled trials (RCTs) comparing low-GI and high-GI diets for weight loss to clarify whether dietary GI impacts body weight.
Based on the study, the researchers reported the following findings:
- Data on 43 cohorts from 34 publications, totaling 1,940,968 adults, revealed no consistent differences in BMI when comparing the highest with the lowest dietary GI groups.
- In the 27 cohort studies that reported results of statistical comparisons, 70% showed that BMI was either not different between the highest and lowest dietary GI groups (12 of 27 cohorts) or that BMI was lower in the highest dietary GI group (7 of 27 cohorts).
- Results of 30 meta-analyses of RCTs from 8 publications demonstrated that low-GI diets were generally no better than high-GI diets for reducing body weight or body fat.
- One notable exception is that low-GI diets with a dietary GI at least 20 units lower than the comparison diet resulted in greater weight loss in adults with normal glucose tolerance but not in adults with impaired glucose tolerance.
- While carbohydrate quality, including GI, impacts many health outcomes, GI as a measure of carbohydrate quality appears to be relatively unimportant as a determinant of BMI or diet-induced weight loss.
"The findings from observational cohort studies and meta-analyses of RCTs showed that there is scant scientific evidence that low-GI diets are superior to high-GI diets for weight loss and obesity prevention," concluded the authors.
The study titled, "Perspective: Does Glycemic Index Matter for Weight Loss and Obesity Prevention? Examination of the Evidence on "Fast" Compared with "Slow" Carbs," is published in the journal Advances in Nutrition.