Restricting your food intake to an eight-hour window — between 7:00 a.m. and 3:00 p.m. — may help with weight loss and improve blood pressure in people with obesity, according to a new study published in the journal JAMA Internal Medicine.
Time-restricted eating, which is a form of intermittent fasting, involves eating only during a set period of time each day — although the details vary when it comes to the length of this period, how early or late in the day it is, and whether this restriction applies every single day or just on some days. Even though there isn’t a set definition for time-restricted eating, studies have shown that some forms of it may have health benefits in areas of metabolic health like weight loss and blood glucose control. But some studies have also failed to show any significant weight loss or other health benefits from time-restricted eating, so it remains an active topic of research.
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For the latest study, researchers compared the effects of time-restricted eating and eating without time restrictions (over 12 or more hours) in 90 adults with obesity over a period lasting 14 weeks. All participants followed a calorie-restricted diet, but some were randomly assigned to also restrict their food intake to between 7:00 a.m. and 3:00 p.m. each day. The researchers were interested in any potential effects on body weight and body fat, as well as indicators of cardiovascular and metabolic health like blood pressure, glucose, insulin, and lipid (cholesterol and triglyceride) levels.
Time-restricted eating linked to greater weight loss
The researchers found that while participants in both diet groups lost weight during the study period, this weight loss was significantly greater, on average, in the time-restricted eating group — 6.3 kilograms (13.9 pounds) compared with 4.0 kilograms (8.8 pounds). When it came to body fat loss, though, the difference between the two groups was smaller and not statistically significant (meaning it could have been due to chance alone) — those in the time-restricted eating group lost an average of 4.7 kilograms (10.4 pounds) of body fat, compared with 3.4 kilograms (7.5 pounds) in the group without time restrictions.
The effect of time-restricted eating on weight loss, the researchers concluded, was equivalent to reducing participants’ caloric intake by another 214 calories each day — in other words, they could eat this many more calories each day and still experience the same amount of weight loss as they would without any time restrictions. What’s more, participants in the time-restricted eating group also experienced lower diastolic blood pressure (the “bottom number” measured between heartbeats) — by an average of 4 mmHg — than those without time restrictions. They also were less likely to report mood disturbances during the study, such as fatigue or symptoms of depression.
There were no significant differences between the two groups when it came to other indicators of cardiovascular or metabolic health, physical activity levels, or sleep outcomes.
The researchers noted that while the results of this study show that time-restricted eating may be helpful for weight loss and other health benefits in people with obesity, more research is needed — with more participants, followed for a longer period of time — to demonstrate the long-term benefits and safety of this eating strategy.
Want to learn more about intermittent fasting? Read “Can Diabetics Do Intermittent Fasting?” and “Intermittent Fasting Can Work.”
