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MAASTRICHT, Netherlands — Eating only during the daytime hours could improve the health of people living with Type 2 diabetes, a new study reveals.

Limiting food intake to a 10-hour window improves metabolism, according to scientists from Maastricht University Medical Center. Time-restricted eating (TRE) has become a trendy dieting plan, with some increasing daily fasting periods for up to 16 hours.

The study, led by Professor Patrick Schrauwen, notes that the modern 24-hour society typically lends itself to endless food availability and disrupted day-night rhythms resulting from irregular sleep activity and regular exposure to artificial light.

In Western nations, people often spread their meals over a 14-hour period, which can lead to the absence of a true nighttime fasting state. Study authors add that these factors all contribute to the development of diabetes. The World Health Organization estimates that the condition causes more than 1.5 million deaths per year.

Diabetes typically develops in middle age, with unhealthy lifestyles playing a major role. In the study, researchers found TRE decreases a person’s 24-hour glucose levels, mainly through lowering nocturnal blood sugar. Average time spent with blood glucose in the normal range increased from 12.2 to 15.1 hours.

Morning fasting glucose was also consistently lower among the TRE group than those on a control diet. Moreover, the diet did not increase the risk of low blood sugar, or hypoglycemia, and there were no serious adverse side-effects of time-restricted eating.

“A daytime 10 h TRE regimen for 3 weeks decreases glucose levels and prolongs the time spent in the normal blood sugar range in adults with Type 2 diabetes as compared with spreading daily food intake over at least 14 h. These data highlight the potential benefit of TRE in T2D,” researchers write in a media release.

10-hour eating window a safe and realistic plan for diabetes patients?

Study authors say an eating window of approximately 10 hours is a safe and effective lifestyle intervention for people with Type 2 diabetes.

The Dutch team described the findings in Diabetologia as “promising.” They also add to a growing body of evidence that late night snacking is bad for your health. Previous studies have shown TRE helps overweight or obese individuals burn more fat, reduce blood sugar, and increase sensitivity to the glucose-controlling hormone insulin.

However, studies hadn’t analyzed these diets in detail and researchers had only used extremely short eating windows of six to eight hours in highly managed settings — making them difficult to implement in daily life.

TRE is sometimes accompanied by unintended weight loss which could increase metabolic health. However, such improvements have also been reported in the absence of weight loss, indicating that additional mechanisms at play when it comes to how restricted eating influences metabolism.

People engaging in TRE lost more weight

Prof. Schrauwen and the team recruited 14 patients between 50 and 75 with a BMI (body mass index) of at least 25. They all had a confirmed case of type 2 diabetes. The study consisted of two three-week interventions, during which the participants either engaged in TRE or were part of the control group — with a four-week “wash-out” period in between each session.

At the start of each period, the team measured each person’s weight and fitted them with a continuous glucose monitoring (CGM) device which measured their blood sugar level every 15 minutes. The groups had to keep to their normal sleep patterns and physical activity and maintain a stable weight.

A food and sleep diary completed during the first intervention helped to ensure that diet during the second session stayed similar in both quantity and quality. During TRE, participants had to consume their normal diet within a 10-hour window during the daytime only — completing their food intake by 6 p.m.

Outside of this time window, the TRE group could only drink water, plain tea, black coffee, or zero-calorie soft drinks. Control volunteers were only required to spread their normal food intake over at least 14 hours, with no other restrictions.

The average eating window for TRE volunteers lasted 9.1 hours compared to 13.4 hours for the control group. Sleep-wake patterns were similar in each case with mean sleep durations of 8.1 hours and 8.0 hours, respectively.

Mean body mass was comparable at the start of both time-restricted eating and control groups and, although volunteers had to remain weight stable, a small but statistically significant weight loss occurred in response to TRE participants.

Half-way through each intervention, study authors assessed liver glycogen levels in the morning following the 10 or 14-hour nighttime fasting period. They measured again at the end of each study period after an 11-hour fast for both groups. In both cases, liver glycogen did not differ significantly between the two groups and an analysis of liver fats revealed no difference in their quantity or composition between interventions.

“Mechanisms underlying the improvement in glucose regulation upon TRE remain unclear. Our results show that TRE did not improve peripheral and liver insulin sensitivity, skeletal muscle mitochondrial function, energy metabolism or liver fat content, all of which are known to be affected in T2D,” study authors say.

Can TRE improve insulin sensitivity?

The researchers say the mechanisms involved in the effects and their implications should be investigated further, with particular focus on studying nocturnal glucose metabolism in more detail. Unlike a previous study into TRE, this one did not show that the protocol had any effect on insulin sensitivity.

However, earlier research used a much shorter six-hour food intake window with the last meal coming at 3 p.m. This resulted in a longer fasting period which may have been more effective but researchers considered it unrealistic to incorporate into the lifestyles of most adults with type 2 diabetes.

“Future studies will be needed to reveal whether the duration of the fasting period is indeed crucial in determining positive effects on insulin sensitivity,” the team recommends.

“Since our TRE protocol was feasible and safe, and resulted in improved 24 h glucose levels, it would be interesting to examine the impact of 10 h TRE on glucose regulation and insulin sensitivity in type 2 diabetes in the long term to address the clinical relevance of TRE,” the team concludes.

South West News Service writer Mark Waghorn contributed to this report.

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