Time-restricted Eating Controls Glucose Levels

A small study determined if time-restricted eating during the day would help blood glucose levels stay under control.

Type 2 diabetes can be caused by a number of modifiable risk factors pertaining to a person’s lifestyle. Some of these modifiable factors may include weight (obesity), physical inactivity, dyslipidemia, and hypertension. Most type 2 diabetes risk factors are modifiable with dietary changes and lifestyle changes. Health care providers suggest increasing physical activity, losing weight, eating healthier, and scheduling regular check-ups as ways to control glucose levels. To avoid glucose intolerance, experts recommend eating healthier foods to regulate weight. Not only is it important to keep control of what foods are ingested and portion sizes, but what times of day foods are eaten is also fairly important. Time-restricted eating can be essential in improving glucose levels. This restricted diet includes eating all meals during a limited period of time of the day. For example, a time restricted diet can involve all meals to be eaten within the hours of 9:00 AM to 6:00 PM every day. So, the question posed is how beneficial the time-restricted eating is.

A small- scale study observed the benefit of a restricted 9-hour time frame diet from developing type 2 diabetes in men. The primary objective of the study was to determine if, without changing other dietary habits, time restricted eating during the day would help blood glucose levels stay under control. Researchers from the University of Adelaide in Australia and the Salk Institute for Biological Studies in La Jolla, CA replicated previous studies experimented in mice in humans. The study lasted for 1 week, observing 15 men who were at risk of type 2 diabetes. The inclusion criteria for the men participating was ages 30-70 years, waist circumference that measured at least 102 centimeters, nonsmoker, weight stable for 6 months prior to trial, up to light physical activity, consumption of less than 140g of alcohol per week, no antihyperglycemic medication, and no personal history of cardiovascular disease, eating disorders, or psychiatric disorders. The 15 men wore a CGM device to measure blood glucose for 7 days from the baseline entry. An accelerometer was also worn to measure activity and sleep patterns. Diaries were kept by each participant to maintain a record of the meals, snacks, and beverages that were consumed during the 7 days.

The men in the trial were only allowed to eat meals within a specific 9-hour time frame each day for a week. The time frame was within 8:00 AM to 5:00 PM, or from noon to 9:00 PM. Water and limited volumes of low-calorie drinks (e.g. diet drinks, herbal tea) were allowed to be consumed outside the eating window. During the restricted time frame, the participants could partake in a normal diet. No restrictions were placed on what the participants could or could not eat. Participants’ activity was measured by the SenseWear armband, worn on the back of the right upper arm. Energy expenditure, number of steps, and time spent sleeping were all collected from the armband.

The mean age and BMI of the fifteen men was 55 years and 33.9 kg/m2, respectively. The body weight on day 0 compared to day 7 was a significant decrease (P < 0.001). The results summed a significant effect from the time-restricted eating starting at 8 AM (P= 0.001) by reducing the glucose by almost 36%. The men consuming meals at 12 PM (P= 0.002) showed about 21% decrease in glucose levels. The differences of reduction in glucose levels between 8 AM consumption and 12 PM consumption reflected the changes in the circadian rhythm. The fasting and postprandial insulin, triglycerides, and gastrointestinal hormones were statistically insignificant. The rate of gastric emptying showed no effect on mealtime. Mean 24-hour glucose showed no statistical difference.

One of the participants in the trial described the time restricted eating as being initially challenging until he found the timeframe that worked for him. The participant noted that his fasting blood glucose tolerance improved significantly, from going from an increased risk level to normal, without changing any foods he ate.

To truly show effectiveness of controlled free-living periods, this trial should be duplicated in larger cohorts.

Practice Pearls:

• Studies proved that the human body is more biologically able to digest the nutrient load at certain times of the day.
• Patients who set a strict time frame for eating between the hours of 8:00 AM and 5:00 PM experienced a greater reduction in blood glucose by almost 36%.
• Time-restricted eating showed that patients at risk of type 2 diabetes can enjoy foods that are considered to be unhealthy, as long as they consume them during the right time of the day.

References:

Cohut, Maria. “To Control Blood Sugar, Set Strict Meal Times.” Medical News Today, MediLexicon International, 2 May 2019, www.medicalnewstoday.com/articles/325072.php.

Hutchison, Amy T., et al. “Time‐Restricted Feeding Improves Glucose Tolerance in Men at Risk for Type 2 Diabetes: A Randomized Crossover Trial.” Obesity, John Wiley & Sons, Ltd, 19 Apr. 2019, onlinelibrary.wiley.com/doi/full/10.1002/oby.22449.

Maya Rudolph, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences, PharmD Candidate