A new small-scale study has found that men at risk of developing type 2 diabetes could benefit from eating all their meals within a restricted 9-hour time frame. Doing so, even without changing other dietary habits, can help keep blood sugar levels under control, the research suggests.
Many factors contribute to a person's risk of developing type 2 diabetes, and some of these, particularly lifestyle and diet, are fully modifiable.
So far, researchers and other specialists have mostly focused on the impact of dietary choices, when it comes to preventing type 2 diabetes in people at risk.
Numerous studies have suggested that eating healthful foods can help people keep their weight in check, as well as avoid glucose intolerance, a characteristic of diabetes that is defined by the body's inability to process blood glucose (sugar).
However, more recently, some investigations have uncovered evidence that in order to keep diabetes and other metabolic conditions at bay, it is important to control not just what and how much you eat, but also when you eat your daily meals.
Studies conducted in mice have shown that time-restricted eating can improve blood glucose levels, even when the animals have a diet that is high in fats.
This kind of diet involves eating all of a day's meals within a restricted period of time, for instance, between 9:00 a.m. and 6:00 p.m. every day.
A team of researchers from the University of Adelaide, in Australia, and the Salk Institute for Biological Studies, in La Jolla, CA, was eager to try to replicate these findings of animal studies in humans.
Thus, associate professor Leonie Heilbronn, a research leader at the university's department of medicine, and colleagues recently conducted a 1-week trial involving 15 men at risk of type 2 diabetes.
A strict time frame, but no other restrictions
The participants, who were aged between 30 and 70 years and who each had a waist circumference of at least 102 centimeters, agreed to eat their meals within a specific 9-hour time frame every day.
"The men, who are at high risk of developing type 2 diabetes, limited their food intake to a 9-hour period per day. Participants undertook time-restricted eating, either from 8:00 a.m. to 5:00 p.m. or later in the day, from midday to 9:00 p.m.," explains Heilbronn.
All through the experiment, the researcher adds, the participants "ate their normal diet." "In fact," Heilbronn notes, "we told them to keep eating all the foods they usually eat," without any other restrictions.
The researchers measured the participants' blood glucose levels every day for the entire week over which the study took place.
Their findings — which now appear in the journal Obesity — indicated that both models of time-restricted eating tested in the study helped improve the participants' glucose control.
"Our results suggest that modulating when, rather than what, we eat can improve glucose control," says Heilbronn, though she admits that she and her colleagues "did see a tiny amount of weight loss in this study, which may have contributed to the results."
Eating food 'at the right time of day'
One study participant, who also took part in an 8-week follow-up study, agreeing to restrict his meals so that they would all fall into the 9:30 a.m. to 7:30 p.m. time slot, notes that he has found the experiment helpful.
"The restricted eating regime was initially challenging," he admits, but it "soon became more manageable." He also notes that he was able to choose a time frame that worked well for him.
"I only ate up until 7:30 p.m., as I found this worked well with my lifestyle," he explains.
"Over the trial," the participant says, "I found that my fasting blood glucose tolerance improved significantly. It changed from 'increased risk' level to 'normal.' This was without changing any of the foods that I like to eat."
This also appears to be one of the main appeals of time-restricted dieting — that a person can continue to indulge in all the foods that they enjoy, without having to worry about the calorie count.
Heilbronn argues that the benefits occur thanks to the fact that such a dietary schedule allows a person's body to process the nutrient intake at the times at which it is most active.
"Time-restricted eating regimes demonstrate that we can enjoy foods that are perceived to be 'bad' for us if we eat them at the right time of day, when our bodies are more biologically able to deal with the nutrient load. And perhaps more importantly, if we allow our bodies to have more time fasting each night."
However, the researcher also cautions that "While these early results show some promise for controlling blood glucose, a larger study over a longer duration is required to fully investigate the effectiveness of this pattern of time-restricted eating."