No matter why you’re trying to lose weight, adjusting the timing of your meals may help. In fact, changing the hours you eat may be just as important as the foods you eat or pass up.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
Eating only during the first eight to 10 hours of the day — a form of intermittent fasting known as “early time-restricted feeding”— makes your body more sensitive to insulin. If you have prediabetes or borderline high blood pressure, your blood sugar levels and blood pressure will normalize.
This eating pattern works because it is in sync with our internal clock (circadian rhythm). Our digestive system is programmed from birth to eat during the day and rest at night when we sleep.
Eating at night requires our bodies to continue producing insulin during the hours we do not require much sugar for energy. As a result, more sugar gets stored as fat. This is why eating at night increases the risk of diabetes and obesity.
“Eating for only eight hours early in the day allows your pancreas to take a break. This improves your metabolism. You will store fewer calories as fat and burn the fat you have,” dietitian Kate Patton, MEd, RD, CSSD, LD, explains.
Our bodies break down simple carbohydrates into sugar, which is released into the bloodstream. We need sugar for energy, but when we have overweight or obesity, any excess sugar we don’t utilize to meet immediate energy needs is stored in cells as fat. Insulin produced in the pancreas facilitates the storage process.
When we don’t eat for a period of time, insulin isn’t needed, and our blood insulin levels drop. This signals our fat cells to release sugar to be used as energy. When insulin levels drop far enough, we burn enough fat to lose weight.
Several intermittent fasting patterns have been studied. Not all were shown to be equally effective.
Alternate-day fasting did not produce greater weight loss or offer any heart healthy benefits above and beyond those obtained from eating a low-calorie diet.
Studies of time-restricted feeding have shown the early eating pattern (8/16, or eating for eight hours after rising and abstaining for 16 hours) to be more effective than a 12/12 pattern in helping to lower insulin levels and normalize blood pressure in men with prediabetes and prehypertension.
Study participants who followed the 8/16 pattern also found they were not hungry in the evening, which made the eating pattern sustainable over the long term.
Not everyone in these studies lost weight, but none gained weight. “There is some flexibility in the schedule. You can eat from 7 a.m. to 2 p.m. or from 9 a.m. to 5 p.m., depending on when you go to sleep and when you rise. The point is that you eat early in the day, and never before bed,” says Patton.
Early time-restricted feeding is a new enough concept that its impact over the long term is unknown. It is thought to be appropriate for most people who could benefit from losing a few pounds, particularly if they are at risk for diabetes.
The diet may not be safe for people with type 1 diabetes, who do not make insulin. “This eating pattern could cause your blood sugar levels to go dangerously high or low,” says Patton.
People taking diabetes medication, people who are pregnant or breastfeeding and anyone with an eating disorder should consult their physician before trying this eating pattern.
As is true with any diet, the best results are obtained by combining early time-restricted feeding with healthy food choices.
“You have to eat well. You won’t lose weight if you are eating poorly,” says Patton. “A plant-based or Mediterranean-style diet is ideal. Such diets emphasize fruits, vegetables, lentils, whole grains and healthy fats and restrict the intake of refined grains and sugars,” she explains.
“If you stay active, follow a healthy diet and avoid mindless snacking, restricting the hours you eat will improve your health, and you will likely lose weight, too.”
This article originally appeared in Cleveland Clinic Heart Advisor.