Dieting to lose weight is not a new concept; however, using an optional intermittent fast to lose weight represents a new twist as the U.S. population become increasingly obese, with escalating diagnoses of diabetes and other metabolic consequences of weight gain. Intermittent fasting is one option of incorporating a very low–calorie diet using a schedule of caloric restriction on some days combined with less restricted calorie intake on others.

Such a calorie-restricted schedule could vary daily, ranging from complete to partial caloric restriction and including a different duration of fast ranging from several hours per day to several days per week. New research from New Zealand suggests this alternation of feast and famine may help decrease weight and A1c values in patients with type 2 diabetes mellitus (T2DM).

Corley BT, et al evaluated 41 participants who were randomized to consecutive (n = 19) or nonconsecutive (n = 22) day fasts, of whom 37 (n = 18 and n = 19, respectively) were included in the final analysis. The primary outcome was a difference in the rate of hypoglycemia between the two study arms; however, secondary outcomes included change in diet, quality of life, weight, lipid, glucose and HbA1c levels, and liver function. The participants had a BMI of 30 to 45 kg/m2, T2DM treated with metformin, and/or diabetic medications and an HbA1c value within the rage of 6.7% to 10%.

A total of 53 hypoglycemic events were reported in the 15 subjects who experienced low blood glucose. Although hypoglycemia was twice as likely on fasting days when compared to nonfasting days, the rates of low blood glucose were no different when consecutive versus nonconsecutive day fasts were compared. In terms of secondary outcomes, both groups experienced weight loss and decreased A1c values; however, there was no statistically significant difference between those two groups.

As would be expected, fasting of any kind increased the rate of hypoglycemia, especially in individuals with T2DM receiving antidiabetic medications. The authors concluded that patient education and medication dose reduction would likely result in fewer than expected hypoglycemic events. According to written correspondence from the researchers to Endocrineweb, “Our study protocol could be adopted for the longer-term studies that will be required to assess the tolerability and sustained efficacy of an intermittent fast.” Unfortunately, they did not respond to further questions about how the groups differed and whether any of the participants were willing to stay with the diet long-term.

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