By David LIu, PHD

Thursday March 22, 2012 (foodconsumer.org) -- Calorie restriction or fasting may be a therapy to help improve the metabolic profile in obesity people with type 2 diabetes, according to a new study published recently in the American Journal of Clinical Nutrition.

The study led by Ilaria Malandrucco of University of Rome Tor Vergata, Rome, Italy and colleagues found that obese people with type 2 diabetes increased their capability of  disposing the glucose load from 59+/-6.3 to 75.5+/- 6.3 ml min -1. m-2 body surface area after they were on a very low calorie diet (VLCD) for seven days.

The authors say calorie restriction in obese diabetics quickly improves glucose control, independently from weight loss.  

The study, according to the authors, was intended to examine the effect of a very low calorie diet on insulin sensitivity and insulin secretion in morbidly obese diabetics which had been unknown until this study.

For the study, 14 severely or morbidly obese people with type 2 diabetes were subject to one-week of calorie restriction and then insulin sensitivity and insulin secretion were assessed in the patients who had body mass index greater than 40 kg/m2.

At the end of the study, the very low calorie diet resulted in a 3.22% weight loss of which 42% was fat loss.   The diet also caused a decrease in fasting plasma glucose and triglycerides.

Additionally, the dietary regimen improved indexes of both first and second-phase insulin secretion, but did not change insulin sensitivity.

The researchers concluded "The marked improvement in metabolic profile, observed in severely obese patients with type 2 diabetes after a 7-d VLCD, was primarily due to the amelioration of β cell function, whereas no contribution of insulin sensitivity was shown."

Calorie restriction is well known to extend one's lifespan.  Recently this dietary intervention and fasting have been also found to be effective in preventing and treating chronic diseases such as cancer.

Keywords: Calorie restriction, type 2 diabetes mellitus, obesity, insulin sensitivity, very low calorie diet