New research suggests that intermittent fasting, cycling through periods of normal eating and fasting may regulate blood sugar (glucose) levels even when accompanied by little-to-no weight loss. The study is published ahead of print in the American Journal of Physiology- Regulatory, Integrative and Comparative Physiology.
In people with mild obesity, intermittent fasting has been found effective for weight loss and an associated reduction of high blood pressure and cholesterol. However, less is known about its effects on people who are extremely obese and whose obesity is caused more by genetics than by lifestyle.
Researchers examined mice with genetic obesity and high insulin and glucose levels. These mice do not produce the appetite-regulating hormone leptin. Previous research suggests that impaired leptin signaling can be a primary cause for obesity in humans. The obese mice followed an alternate day feeding schedule for two and a half weeks, with unlimited access to food on feeding days.
Neither a control group of lean mice following the same alternate day eating pattern nor the obese mice lost weight throughout the trial. However, on non-feeding days, "improvement [of glucose control] in both control and [obese] mice occurred in the absence of weight loss," the researchers wrote. The fact that blood glucose regulation improved only on non-feeding days, but occurred without significant weight loss, suggests that the benefits of intermittent fasting "likely vary considerably on a day-to-day basis," the researchers said.
Swoap, S.J. et al. (2019) Alternate day feeding leads to improved glucose regulation on fasting days without significant weight loss in genetically obese mice. American Journal of Physiology- Regulatory, Integrative and Comparative Physiology. doi.org/10.1152/ajpregu.00140.2019.