Low-Carbohydrate vs Low-fat Diet Success In Patients With Prediabetes Differs According to Fasting Insulin Levels

Fruit and vegetables
Fruit and vegetables
Fasting plasma glucose, insulin, and insulin sensitivity levels were measured to determine their prognostic value as markers for long-term weight loss.

This article is part of Endocrinology Advisor’s coverage of the American Diabetes Association’s 77th Scientific Sessions (ADA 2017), taking place in San Diego, CA. Our staff will report on medical research and technological advances in diabetes and diabetes education, conducted by experts in the field. Check back regularly for more news from ADA 2017.

The effectiveness of a low-carbohydrate diet compared with a low-fat diet in patients with prediabetes and obesity varied by the patients’ fasting insulin levels, according to research presented at the American Diabetes Association (ADA) 77th Scientific Sessions.1

There has been considerable debate regarding the most effective diet for achieving sustainable weight loss. Although some findings support the benefits of a low-carbohydrate diet, other evidence suggests that a low-fat diet is the optimal approach.2

A new study conducted by researchers from several US and international universities aimed to clarify this issue by comparing the results of each type of diet in individuals with obesity.

To investigate the potential prognostic value of fasting plasma glucose (FPG) level, insulin level, and insulin sensitivity as markers for long-term weight loss, the researchers measured these values in 171 participants and assigned them to 1 of 2 diets for a period of 2 years: a low-carbohydrate diet, which consisted of 20 g/d low-glycemic vegetables and unlimited fat and protein, with subsequent intermittent increases in carbohydrates (5 g/d per week) as appropriate; or a low-fat diet consisting of 1200 to 1800 kcal/d and ≤30% calories from fat. Participants also received comprehensive behavioral treatment.

Among participants with prediabetes (FPG ≥100-125 mg/dL; n=38) with high fasting insulin levels, the findings showed a greater mean weight loss on the low-fat diet vs the low-carbohydrate diet (–6.93 vs 0.26 kg, respectively; P=.004). Participants with prediabetes with low fasting insulin levels, however, lost more weight on the low-carbohydrate diet vs the low-fat diet (–16.03 vs –9.94 kg, respectively; P =.084).

In individuals with normal FPG levels (FPG <100 mg/dL, n=133), no difference was observed between those with high vs low fasting insulin levels on either diet (0.58 kg; P =.78), and similar results were found when using measures of fasting insulin sensitivity vs fasting insulin levels.

“Pretreatment fasting insulin in individuals [with prediabetes and obesity] determines long-term weight-loss success by ad libitum low-[carbohydrate] or caloric-restricted low-fat diets,” the researchers concluded. “These results may be helpful [in] developing personalized strategies for weight loss.”

Disclosures: The researchers report numerous financial relationships with pharmaceutical and other companies, including Novo Nordisk A/S, Weight Watchers, Inc., Eisai, Atkins Nutritionals, Takeda Pharmaceutical Company Limited, Janssen Pharmaceuticals, DuPont, and Gelesis, among others.

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  1. Hjorth MF, Zohar Y, Astrup A, et al. Pretreatment fasting plasma glucose and insulin determine long-term dietary weight loss success on low-carbohydrate vs low-fat diet. Presented at: American Diabetes Association (ADA) 77th Scientific Sessions; June 9-13, 2017; San Diego, CA. Abstract 73-LB.
  2. Hu T, Katherine T. Mills KT, Yao L, et al. Effects of low-carbohydrate diets versus low-fat diets on metabolic risk factors: a meta-analysis of randomized controlled clinical trials. Am J Epidemiol. 2012;176(suppl 7):S44-S54.