2 low-calorie days a week could aid weight loss, blood sugar control in diabetes

Medical News Today

6 days ago

Weight loss can be effective in managing type 2 diabetes, a condition where a person cannot control their blood glucose levels.However, losing weight can be challenging, so finding a method of weight control that fits with a person's lifestyle is important.A new study has shown that several forms of energy restriction can help people with obesity and type 2 diabetes to lose weight and manage their blood glucose.As the 5:2 diet, time-restricted eating, and continuous energy restriction were all beneficial, experts suggest that people opt for the form of energy restriction they find easiest to follow.Type 2 diabetes is an increasingly common condition, and a serious public health concern. Forecasts predict that it will affect close to 10% of the world's population by 2050.The condition, in which a person's cells stop responding to insulin, resulting in uncontrolled blood glucose (sugar) levels, is strongly linked to overweight and obesity. Losing weight can help to manage the symptoms, and significant weight loss may even reverse type 2 diabetes in some people.A new study from The First Affiliated Hospital of Zhengzhou University, China, tested three methods of energy restriction for weight loss and blood glucose control in people with obesity and type 2 diabetes. The study, which was presented at ENDO 2025, the Endocrine Society's annual meeting in San Francisco, CA, suggests that while all three methods showed benefits, intermittent energy restriction (IER) — characterized by 5 days normal eating and 2 days of very low energy intake each week — was slightly more effective in reducing fasting blood glucose, improving insulin sensitivity, and lowering triglycerides.These findings are yet to appear in a peer-reviewed journal.Lead researcher Haohao Zhang, PhD, chief physician at The First Affiliated Hospital of Zhengzhou University in Zhengzhou, China, told Medical News Today:'All three dietary approaches — IER, TRE [time-restricted eating], and CER [continuous energy restriction] — were beneficial because they reduced total calorie intake, a key factor in improving glycemic control (HbA1c) and promoting weight loss in obese individuals with type 2 diabetes. Regardless of the method, calorie restriction facilitated weight loss, reducing insulin resistance and improving glycemic control.'3 ways to reduce energy intake in diabetesThe researchers recruited 90 people with type 2 diabetes and obesity into their study. They then randomly assigned them to three groups, each of which followed a different diet program. At the start, participants had a mean age of 36.8 years, and a mean duration of type 2 diabetes of 1.5 years.In total, 63 people (18 women and 45 men) completed the 16-week, nutritionist-supervised program.The researchers measured glycated haemoglobin (HbA1c) — a standard test for type 2 diabetes that measures blood glucose over the previous 90 days — at the start and end of the trial. Optimal HbA1c is less than 5.7%, with 6.5% or over indicating type 2 diabetes.At the start of the study participants had a mean HbA1c, of 7.42%, and a mean body mass index (BMI) of 31.7 kilograms per square meter (kg/m²).Each group followed one of three low-calorie diet programs, with the same overall energy intake each week, as Zhang explained to MNT:intermittent energy restriction (IER) — This group consumed very low calories (500–600 kilocalories [kcal]) on two nonconsecutive days per week, with normal eating on the remaining 5 days, adhering to a weekly total calorie goal. Eating times were not restricted, but calorie intake was limited on fasting days.time-restricted eating (TRE) — Participants ate within a 10-hour window (6–8 am to 4–6 pm) each day, fasting for the remaining 14 hours. Within the eating window, food intake was controlled to match the weekly calorie goal consistent across all groups.continuous energy restriction (CER) — These people followed a low-calorie diet without specific time restrictions, maintaining a consistent weekly calorie deficit to match the other groups' weekly calorie intake. Which diet leads to weight loss and better blood glucose control?Participants in all three groups lost weight and showed better blood glucose control by the end of the 16-week study. Mean weight loss for the 3 groups was 7.5 kilograms (kg), with those in the IER group losing the most, and participants in all three groups reduced their HbA1c by more than 1%.David M. Cutler, MD, a board-certified family medicine physician at Providence Saint John's Health Center in Santa Monica, CA, not involved in the study, told MNT that:'Data from the study showed statistically significant benefit in weight loss and reduction in hemoglobin A1c, which indicates better control of diabetes. However, there was no statistically significant difference between the three groups for these measures.'Further research needed in diverse populationsCutler pointed out that: 'This study was conducted at The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan Province, China. So, it remains to be seen if such dietary restrictions would yield similar results in an American population. Further research would need to be done in a larger, more diverse population to see which form of dietary restriction is most likely to be beneficial.'Zhang agreed, saying that future studies should 'include broader populations — e.g. [of] varying ages, ethnicities, or diabetes durations — to assess the generalizability of these dietary approaches, and explore psychological and behavioral factors affecting adherence to IER, TRE, and CER to optimize patient support and intervention design.'What is the best way to lose weight and manage type 2 diabetes?'The fact that only 63 of the 90 patients actually completed the study speaks to the fact that adhering to dietary restrictions is difficult,' Cutler told MNT.Zhang recommended the 5:2 diet 'due to its greater benefits in reducing fasting blood glucose, improving insulin sensitivity, lowering triglycerides, and achieving higher compliance (85%).'He added that it 'offers flexibility, allowing normal eating for five days and calorie restriction on two non-consecutive days, which may be easier to sustain than daily restrictions (CER) or strict eating windows (TRE).''However,' he told MNT that people should consult a dietitian and that, 'the choice should be individualized, considering patient preferences, lifestyle, and adherence capacity.'Both he and Cutler emphasized that any weight-loss regime will benefit people with obesity and type 2 diabetes, with Cutler concluding that:'The major take home message seems to be that any dietary restriction can be helpful for weight loss and managing type 2 diabetes if [the] patient will stick to it. My personal recommendation is to eat less, and mostly vegetables. And for people who want more structure than that, they should try any form of intermittent fasting or specific calorie restriction which is most appealing to them.'