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Limiting one’s eating window to a certain period may help with weight loss and blood sugar control in people with type 2 diabetes. Morsa Images/Getty Images
  • New research suggests that time-restricted eating could be an effective strategy for weight loss and improved blood sugar levels in individuals with type 2 diabetes.
  • A recent randomized controlled trial found that participants who limited their eating to an eight-hour window from noon to 8 p.m. experienced greater weight loss compared to those who reduced their overall calorie intake through calorie counting.
  • However, researchers caution that individuals should work closely with their physician, as medications and specific dietary requirements may influence the effectiveness of their diet plan.

Weight loss is an important target for individuals diagnosed with type 2 diabetes, a condition closely linked to excess weight or obesity; however, the most effective dietary approach remains unclear.

In a new study, participants who limited their eating to a specific window from noon to 8 p.m. experienced greater weight loss compared to those who simply reduced their overall calorie intake through calorie counting.

Time-restricted eating has gained popularity, but prior to this study, no research had specifically explored an eight-hour eating window in individuals with type 2 diabetes.

The study involved 75 individuals, ages 18–80 years, who had both obesity and type 2 diabetes and who were divided into three groups: one followed time-restricted eating, another practiced calorie restriction and the third served as the control group.

Those in the time-restricted eating group consumed their meals only from noon to 8 p.m., while the calorie restriction group had the flexibility to eat at any time of the day but monitored their calorie intake using the MyFitnessPal mobile app.

Their goal was to reduce their caloric intake by 25% of the maintenance calories required to maintain their current weight, while the control group continued with their regular diet without any specific interventions.

The study was presented at Nutrition 2023, the annual meeting of the American Society for Nutrition, held on July 22–25 in Boston.

During the six-month duration of the study, the researchers observed that individuals following the time-restricted eating diet experienced a 3.55% reduction in body weight compared to the control group.

To put this into perspective, this would equate to a person weighing 275 pounds losing approximately 10 pounds.

The group practicing calorie restriction, however, did not show any significant weight loss compared to the control group.

Both the time-restricted eating and calorie restriction groups exhibited decreased blood sugar levels (HbA1C) in comparison to the control group, with reductions of approximately 0.91% and 0.95%, respectively.

The researchers also investigated whether these dietary strategies could improve cardiometabolic risk factors, such as blood pressure, LDL cholesterol levels, and fasting glucose.

However, the weight loss achieved through time-restricted eating fell short of the 5% threshold typically associated with improvements in these factors.

Vicky Pavlou, registered dietitian nutritionist, and a doctoral student at the University of Illinois at Chicago, and author of the study, spoke to Medical News Today, saying “we found that eating all calories within an 8-hour window is a good alternative to calorie counting for people with type 2 diabetes who want to lose weight and improve their A1C.”

“The time-restricted eating (TRE) group lost 4.28% of their body weight in 6 months and the calorie counting group lost 2.55% of their body weight in 6 months. Both groups reduced their HbA1C by 1%,” she said.

Dr. Seun Sowemimo, board certified surgeon at Prime Surgicare in Freehold, New Jersey, who was not involved in this research, highlighted that “using a combination of disease management tools is more effective than a single effort.”

“Time-restricted eating (intermittent fasting) is a powerful strategy for weight loss and blood sugar control because it allows the body to switch from burning sugar to burning fat, resulting in weight loss,” he said.

“It also reduces the frequency of blood glucose spikes, which can trigger insulin spikes, and supports diabetes control,” Dr. Sowemimo explained.

“Consuming foods with naturally high fiber content, rather than processed foods with added sugar, can also improve diabetic control. Natural fiber foods help regulate sugar absorption, allowing for a gradual release into the bloodstream, unlike processed foods with free sugar, which are rapidly absorbed, leading to elevated sugar levels and insulin spikes. I also recommend people with diabetes eat fresh fruits because the myth regarding the sugar content in fruit is false.”
— Dr. Seun Sowemimo

Crystal Scott, registered dietitian at Top Nutrition Coaching, who was also not involved in the study, told MNT that “time-restricted eating may help improve blood sugar control in individuals with type 2 diabetes.”

“By avoiding constant grazing and giving the body longer periods without food intake, the insulin response may become more efficient,” Scott explained. “Studies have shown that time-restricted eating can lead to better glucose levels, reduced HbA1c levels (a marker of long-term blood sugar control), and improved insulin sensitivity. But in this study, it didn’t.”

Dr. Sowemimo noted that this “study adds another layer of clinical evidence that the timing of food consumption is a major contributing factor to diabetes management, weight loss, and overall well-being.”

“Patients with diabetes can be safely prescribed time-restricted eating but should do so in partnership with their physician,” Dr. Sowemimo said.

Scott also pointed out how important it is to explore confounders, such as the participants’ diabetic medication usage, water intake, activity level, and stress-management approaches.

“For a study like this one regarding dieting strategies to be fully successful, many other components need to be accessed at the same time,” Scott explained.

Scott also highlighted that this study shows that although individuals may recognize the need to practice time-restriction measures to see weight loss, it also demonstrates that there are “easier approaches to weight management that doesn’t involve tracking every piece of food.”