Calorie Restriction vs. Bariatric Surgery for T2D Remission

Calorie restriction vs. bariatric surgery: a low-calorie diet was a safe and effective treatment for individuals with newly diagnosed T2D and obesity.

First-line treatment for patients with T2D includes anti-diabetic medication therapy. Bariatric surgery has also been endorsed for individuals with new onset of diabetes and a BMI >30. National guidelines briefly mention dietary recommendations and completely omit any reference to diabetes remission.

The researchers of this study believe lifestyle can be an essential component for the remission of the disease. Previous studies looked at lifestyle modifications and T2D remission. Limm et al. found that insulin resistance and pancreatic beta‐cell loss can be reversed with an energy‐restricted 600 kcal/day diet. Steven et al. found a sustainable normalization of fasting plasma glucose in 40% of individuals on an eight-week 624–700 kcal/day diet. Previous findings were flawed due to the broad definition of remission that included fasting plasma glucose, HbA1c, oral glucose tolerance test, and beta-cell function. This review assessed the safety and efficacy of energy-restricted interventions that achieved remission of T2D. The primary outcome measured A1c <6.5% in individuals without hypoglycemic medications who used an energy-restricted diet as an intervention. The secondary outcome measured weight change, decrease in A1c, and serious adverse events.

This systematic review looked at the remission of patients with T2D on a calorie-restricted diet. The search selected randomized control trials or intervention studies published in English within the last ten years. The population included adults >18 years with T2D of any duration and any medication regimen. The intervention was an energy-restricted diet, and the control group was standard of care. The study excluded cohort, crossover, and case-control trials and any studies with children or animals. Studies with a drug-based intervention above standard care, bariatric surgery, or carbohydrate restriction were also excluded. The Pearson correlation coefficient (r‐value) was used to calculate some of the final variables, while the Downs and Black quality assessment tool measured the risk of bias.

The researchers analyzed four randomized controlled trials and four single‐arm studies, with a cumulative sample size of 5,764 individuals. They found that weight loss was associated with an increased rate of remission (r = 0.83). Gregg et al. found that the probability of a one-year remission was highest among individuals who lost >6.5% weight (16.4%; 95% CI: 14.5%–18.6%). The DiRECT study found that remission of T2D was achievable for 70% of those who maintained >15 kg weight loss; however, only 24% could attain this weight loss despite a severe calorie restriction diet. Sarathi et al. found that no patients had a recurrence of T2D if they achieved remission and maintained/decreased their weight from their three-month weight loss. Gregg et al. found that 33% of those who had remission returned to having T2D every year.

The researchers also found no association between baseline weight and remission rates (r = −0.43). Lean et al. found no association between baseline BMI and probability of remission at 24 months. Umphonsathien et al. and Sarathi et al. found no association between baseline weight and remission rates. Gregg et al. did find an association between lower BMI and the probability of further remission (p < 0.001). There was an inverse association between the length of diabetes and the remission rate (r = −0.94). The calorie-restricted diet had few adverse events and no participant withdrawals from an adverse event.

A low-calorie diet had similar T2D remission rates to bariatric surgery, and calorie restriction had few adverse events and can be safely used on newly diagnosed individuals with diabetes. Emphasizing lifestyle modification can be an excellent tool for combating the disease. New recommendations should include the target weight loss of >10% body weight in individuals with obesity. More research is needed to determine the ideal level of calorie restriction and the assistance necessary for long‐term remission. Weaknesses of the study include the omission of unpublished research, not calculating odds ratios. The inclusion of single-arm studies might have increased the risk of bias.

Practice Pearls:

• The weight loss of >10% body weight in people with obesity was associated with an increased rate of T2D remission.
• The remission rate of T2D achieved through calorie restriction is high and comparable to bariatric surgery.
• The DiRECT study found that remission of T2D was achievable for 70% of those who maintained >15 kg weight loss. However, only 24% were able to attain this weight loss.

References for “Calorie Restriction vs. Bariatric Surgery for T2D Remission”:
Jacob E, Avery A. Energy-restricted interventions are effective for the remission of newly diagnosed type 2 diabetes: A systematic review of the evidence base. Obes Sci Pract.

Steven S, Hollingsworth KG, Al‐Mrabeh A, et al. Very low‐calorie diet and 6 months of weight stability in type 2 diabetes: pathophysiological changes in responders and nonresponders. Diabetes Care.

Kornelia Ilias, Pharm.D. Candidate, Creighton University School of Pharmacy and Health Professions