Intermittent fasting may be effective weight loss strategy in patients with type 2 diabetes

A systematic review and meta-analysis of seven studies found that intermittent fasting induced a greater decrease in body weight compared to regular diet but was not associated with any greater reduction in HbA1c levels.


Intermittent fasting may be a viable alternative strategy for weight loss in patients with type 2 diabetes, a systematic review and meta-analysis found.

Interventional studies of adults with type 2 diabetes that compared any intermittent fasting intervention to a standard diet consisting of either healthy-pattern dietary recommendation with caloric deficit or normal caloric intake were eligible for inclusion. Intermittent fasting interventions included 24-hour complete fasting, intermittent restricted energy intake (25% total caloric intake), and time-restricted feeding (feeding allowed for only a window of four to eight hours daily, with 16 to 20 hours of fasting). Researchers examined the impact of fasting versus regular diet on two primary outcomes: weight reduction (mean change in body weight) and glucose-lowering effect (mean change in HbA1c). Results were published online on Dec. 15, 2020, by the Journal of Clinical Endocrinology & Metabolism.

Seven studies (six randomized parallel-arm trials and one randomized crossover trial) with a total of 338 participants (mean age, 56.3 years; mean body mass index [BMI], 35.65 kg/m2; mean baseline HbA1c level, 8.8%) were included in the analysis. Compared to regular diet, intermittent fasting induced a significantly greater decrease in body weight (difference, −1.89 kg; 95% CI, −2.91 to −0.86 kg), with no significant between-study heterogeneity. In sensitivity analyses, the additional weight loss induced by fasting was greater in studies with populations with BMI greater than 36 kg/m2 (difference, −3.24 kg; 95% CI, −5.72 to −1.15 kg) and in studies with a duration of four months or fewer (difference, −3.73 kg; 95% CI, −7.11 to −0.36 kg). However, compared to standard diet, intermittent fasting was not associated with further reduction in HbA1c levels (difference, −0.11%; 95% CI, −0.38% to 0.17%), with no significant between-study heterogeneity.

Among other limitations, different intermittent fasting protocols were used across studies, the authors noted. In addition, most included trials lasted between one and 24 weeks, so it is uncertain whether participants had long-term adherence to the plan, they said.

“In conclusion, given the historical challenges of non-pharmacological approaches in [type 2 diabetes], our results support IF [intermittent fasting] as a non-inferior alternative strategy for weight loss. Our analyses demonstrate the therapeutic potential of IF as a weight reduction strategy in [type 2 diabetes] and highlight the need for further research in this field,” the authors wrote.