Effects of Intermittent and Continuous Calorie Restriction on Body Weight and Insulin Sensitivity Among Prediabetics

Abstract

Background: Type 2 diabetes is a worldwide health concern. Intermittent calorie restriction (ICR) may be a promising dietary approach to prevent type 2 diabetes, as it has been suggested to improve insulin sensitivity among individuals with prediabetes. Objective: The present research aimed to evaluate whether ICR leads to stronger improvements than continuous calorie restriction (CCR) with regard to weight loss and insulin sensitivity among study participants of a randomized controlled trial (RCT), who had prediabetes at baseline. Methods: A secondary analysis of published data from a 50-week RCT on the metabolic effects of ICR vs. CCR vs. a control diet among overweight or obese persons was carried out, restricted to study participants with prediabetes at baseline (n=63, age range 35-65 years, 49% women). Differences in insulin sensitivity parameters (HOMA-IR, fasting insulin, fasting glucose, HbA1c, and IGF-1) were evaluated by mixed linear models. Results: Although individuals in the ICR group showed slightly greater weight loss compared to those in the CCR group, there were no statistically significant differences in weight loss or biomarkers of insulin sensitivity between the groups after week 12, week 24, or week 50 of the study. Additional exploratory analyses showed that triglycerides decreased more strongly with ICR than CCR after week 12 (-37% ±30.3% vs. -18.8% ±26.5%) and week 24 (-40.3% ±44.3% vs. -8.6% ±32.5%), but not after week 50 (-26.3% ±31.7% vs. -13.3% ±35.5%). When assessing the effects of overall weight loss, irrespective of the method used to achieve it, on biomarkers, stronger weight loss was statistically significantly associated with greater decreases in fasting glucose, insulin, HOMA-IR, and HbA1c. By contrast, an increase in IGF-1 at week 12 was observed with greater weight loss. It was also found that higher baseline HOMA-IR predicted lower overall weight loss during the trial. Conclusions: The present study showed that there are no differences between ICR and CCR with regard to weight reduction and insulin sensitivity among people with prediabetes. However, this study did show that ICR could be more beneficial than CCR with regards to reducing triglyceride levels, a finding that needs to be confirmed in other studies.