How effective are low energy diets, in which calories are strictly limited, for weight loss, glycemic control, and reducing insulin burden?
Diet intervention is considered a mainstay in diabetes management. Weight control can be difficult for people who have both obesity and type 2 diabetes mellitus (T2DM), especially if they are receiving insulin therapy. Studies have proven that weight reduction in a person with diabetes leads to better glycemic control, less microvascular complications, and can even lead to remission of T2DM. Bariatric surgery has shown great promise, but because of its economic restraints, its availability is limited for most people. Questions remain about the best diet for a person with diabetes. This study focused on low energy diets, which consist of dense foods with fewer calories.
This trial was a prospective, parallel–group, non-blinded, randomized clinical trial in two hospitals in London, UK. The goal of the trial was to compare the effects of a low energy diet program with behavior modification and physical activity, versus standard treatment of diabetes, on weight loss, insulin burden, and glycemic control in patients with type 2 diabetes and obesity receiving insulin therapy. The 12-week low energy diet started after randomization. It was followed by 12 weeks of structured food reintroduction, and then ongoing follow up in combination with an energy deficit diet at three-month intervals until 12 months. The primary outcome was body weight loss at 12 months. Secondary outcomes included insulin usage, HbA1c, fasting plasma glucose, fasting plasma C- peptide, hormonal responses during the MMTT, serum lipids, blood pressure, body composition, and QoL.
Between November 2014 to June 2017, 90 participants were recruited and grouped in a 1:1 ratio. Follow up ended in May 2018. Twenty-one participants were lost to follow up with no apparent reason for withdrawal. The results of the primary outcome found that the mean reduction in body weight at 12 months was 9.8 kg in the intervention group and 5.6 kg in the control group (adjusted difference −4.3 kg, 95% CI −6.3 to −2.3; p<0.0001. During the initial 12 weeks, body weight in the intervention group reduced by 13.3 kg compared with 4.5 kg for the control group (p<0.0001), which continued to reduce during the food reintroduction phase to 14.1 kg vs. 6.1 kg, respectively. At 12 months, weight loss of ≥5% of body weight occurred in 26 of 33 (79%) participants in the intervention group compared with 17 of 36 (47%) in the control group (OR 4.15, 95% CI 1.43 to 11.99). Weight loss ≥10% occurred in 16 of 33 (48%) in the intervention group compared with 7 of 26 (19%) in the control group (OR 3.90, 95% CI 1.34 to 11.38).
The results of the secondary outcomes found at 12 months, 13 of 33 (39.4%) participants in the intervention group had discontinued insulin compared with 2 of 36 (5.6%) in the control group (p<0.001). At 12 months, there was a reduction in daily total insulin dose, reducing by 47.3 units (26.6 units/day) in the intervention group and 33.3 units (52.4 units/day) in the control group. At 12 months, mean HbA1c fell by 0.43% in the intervention group and by 0.09% in the control group with an adjusted difference of −0.56% (95% CI −1.17 to 0.04; p=0.07). There was no difference in fasting and postprandial levels of C- peptide or GLP-1 between the two groups. Mean waist circumference reduced by 9.9 cm in the intervention group compared with 4.6 cm within the control group (adjusted difference −4.8, 95% CI −7.4 to −2.2; p<0.0001). There was no significant difference in the adverse events experienced by both groups. Those in the intervention group reported a significantly improved QoL score at 12 months, while QoL was unchanged in the control group.
This randomized clinical trial demonstrated that a low energy total diet replacement based lifestyle intervention safely induces weight loss, reduces insulin requirements, and improves the quality of life, specifically in participants with long–standing type 2 diabetes and obesity receiving insulin therapy. Postprandial glucose clearance and fasting plasma glucose had more significant improvement with the intervention group at 12 months, indicating enhanced insulin sensitivity.
Weight loss for someone on insulin therapy can be difficult. In the study, those who stopped insulin were mainly men, had lower baseline insulin dosage and HbA1c, and achieved a more significant weight loss at 12 months. Lower energy diet, including behavior modification and physical activity, was proven to be successful. Questions still remain about how to maintain weight loss after six months.
- Low energy diets, including behavior modification and physical activity, are effective at reducing weight, lowering insulin burden, and improving quality of life.
- Diet and exercise are mainstay treatments of T2DM.
- Low energy diets are safe and effective.
Brown, Adrian, et al. “Low-Energy Total Diet Replacement Intervention in Patients with Type 2 Diabetes Mellitus and Obesity Treated with Insulin: A Randomized Trial.” BMJ Open Diabetes Research & Care, vol. 8, no. 1, BMJ Specialist Journals, Jan. 2020, p. e001012, doi:10.1136/bmjdrc-2019-001012.
Villani, Valentina, and Laura Perin. “Diet as a Therapeutic Approach to Diabetes Management and Pancreas Regeneration.” Transplantation, Bioengineering, and Regeneration of the Endocrine Pancreas, Elsevier, 2020, pp. 215–27, doi:10.1016/b978-0-12-814831-0.00015-4.
Antonio Bess, Pharm D Candidate, Florida A&M University