- Time-restricted eating is a form of intermittent fasting that some believe could bring metabolic benefits.
- Animal studies on time-restricted eating that have demonstrated weight loss and lower blood glucose have proved difficult to reproduce in humans.
- However, a recent small study has shown that time-restricted eating may have a positive effect on overweight older people with type 2 diabetes.
Whether or not eating in a fixed time window each day has any metabolic benefits is a question researchers have been asking in recent years.
Referred to as time-restricted eating, which is a form of intermittent fasting, animal and human studies have shown significant benefits of this practice, including improved blood glucose and weight loss.
According to researchers, one group that could benefit from time-restricted eating is people with type 2 diabetes, as losing weight and reducing blood sugar could help reduce the risk of developing complications.
Now, a small study on 14 overweight and obese type 2 diabetes patients in the Netherlands has shown that a time-restricted eating window of 10 hours, both improved the amount of time spent in a healthy glycaemic range and decreased fasting glucose compared to a 14-hour eating window.
The results of the study have been published in Diabetologia.
How fasting may help diabetes
Type 2 diabetes is a form of diabetes where the cells in the body become resistant to the hormone insulin, which normally helps to move glucose—a form of sugar—from the blood into the cells to provide them with energy.
In people with type 2 diabetes, cells become less able to do so. As blood sugar levels rise, the body fails to adequately compensate for insulin activity. This increase in blood sugar can lead to many complications, including cardiovascular disease and nerve damage if left untreated or not controlled.
The number of cases of type 2 diabetes has almost quadrupled in less than 40 years and makes up around 95% of the total number of cases of diabetes worldwide, according to a recent World Health Organization report.
Losing weight can help to reduce insulin resistance, and improving blood sugar levels through diet can reduce the risks associated with type 2 diabetes.
While some studies have shown that time-restricted eating can help with weight loss, its impact on blood sugar in patients with type 2 diabetes is less well established.
Finding a time window that works
Researchers so far have investigated time-restricted eating windows as short as 6 hours, but generally the shorter the eating window and longer the fast, the harder it is for people to stick to, which makes adherence less likely.
Dr. Lucy Chambers, head of research communications at Diabetes U.K., told Medical News Today:
“It’s important to remember that there’s no one diet for type 2 diabetes, and the best diet is one you can stick to. If you’re living with type 2 diabetes and are trying to lose weight, having the right support is also crucial.”
One of the reasons researchers think that time-restricted eating could help improve metabolism is that humans (and other animals) are designed to have a fasting period during their rest or sleep phase each day. Demands of modern life, including shift work and increased availability of food, have made it less likely that we observe this fasting period, disrupting our metabolism.
The researchers in this study hypothesized that levels of glycogen, a way the body stores sugar, would be lower following time-restricted eating. They suggested lower glucose availability could improve insulin sensitivity due to an increased need to replenish glycogen stores.
They also wanted to investigate whether a 10-hour eating window could lead to metabolic improvements in overweight and obese type 2 diabetes patients ages 50-70, making it potentially easier to follow in everyday life.
To test this hypothesis, researchers divided the participants into two groups: The first group’s eating times were restricted to a 10-hour window and the placebo group to at least 14 hours for a period of three weeks.
They observed a 4 week “wash-out period” before researchers switched the groups and repeated the experiment. This meant each participant “was their own control,” explained author Charlotte Andriessen, a Ph.D. student at Maastricht University, Netherlands, who worked on the study, to MNT.
As part of the trial, the researchers fitted participants with a glucose monitoring device for both of the three-week trial periods, which measured blood glucose every 15 minutes. They also measured their fasted glycogen stores in the middle week of each phase of the experiment. Lastly, they measured participants’ body compositions and energy expenditures inside a respiration chamber for a 36-hour period in a clinic.
Limiting eating to 10 vs. 14 hours
Researchers found no decrease in glycogen stores in the liver following time-restricted eating. However, they note they didn’t measure this at night when individuals would have been fasting.
However, they did find that overall time in a healthy glycaemic range increased by approximately 3 hours a day, and fasting glucose was lower when the participants’ eating was restricted to a 10-hour window.
The study didn’t account for the potential impact of some participants’ glucose-lowering drugs. The group was also small and the participants older, making the results not generalizable to a wider population.
“It may be possible that a younger group of volunteers would be more sensitive to a time-restricted eating regime, as aging also decreases insulin sensitivity and mitochondrial function, both of which are important in switching from using more glucose for energy during the day to fats during the night,” Andriessen said.
“The main reason for us to include postmenopausal women as opposed to pre-menopausal women is related to the fluctuations in hormones that occur with menstruation,” she pointed out.
The results, Andriessen said, are also not generalizable to people with prediabetes, another group that has been touted to potentially benefit from time-restricted eating.
The authors behind the study say larger studies are needed to look at the “more feasible” 10-hour restricted eating window.
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