A younger sibling to intermittent fasting, time-restricted eating (TRE) limits food consumption to an 8-to-12-hour window each day. Its approachable focus on timing, rather than food choice or portion size, makes TRE easier to follow than other weight-management plans, experts say.
Plus, studies over the past decade have demonstrated weight loss and other health benefits of TRE for everyone from healthy young adults to people with obesity and metabolic syndrome to shift workers.
"If you're eating from 9 a.m. to 7 p.m. on Monday, you're doing that on Tuesday, Wednesday, and Thursday for the foreseeable future," said Emily Manoogian, PhD, at the recent World Sleep Conference in Singapore. The steady schedule is “one of the main factors that has separated it from other forms of intermittent fasting.”
Why TRE Works
The most straightforward explanation: If you’re eating in predefined windows of time that don’t stretch late into the night, you’re likely to eat fewer calories — and burn more energy than you take in, resulting in weight loss. But recent studies reveal other, more complex biological mechanisms at play.
Researchers attribute some of TRE’s benefits to metabolic switching — the process wherein your body “switches” to breaking down stored fat for energy after using up stored glucose. This usually happens following 10 to 12 hours of fasting and can reduce body fat.
Other TRE benefits have been linked to its effect on our circadian rhythm, the internal clock that regulates our sleep-wake cycles and helps control our metabolism. Late-night eating can disrupt that rhythm and has been associated with chronic diseases like obesity, Manoogian said. Some studies have shown that an early TRE plan (starting as early as 8 a.m.) improves circadian clock gene expression, which may promote a healthy rhythm and more efficient metabolism. “The circadian system is anticipatory,” Manoogian said. “You need to be able to prepare for when you're going to eat.”
The Research Behind TRE
Research by Manoogian and others in 2020 included 19 adults with metabolic syndrome who followed a 10-hour TRE plan. After 12 weeks, they lost weight, had lower blood pressure and atherosclerosis-causing fats, and slept more restfully. They also “naturally” adopted consistent meal and wake times, Manoogian said.
She and her collaborators expanded the study to 108 adults with metabolic syndrome for a three-month randomized controlled trial published in 2024. Half of participants followed a personalized 8-to-10-hour TRE plan. They saw a 0.1% decrease in A1c (average blood sugar over the past three months) — an amount that’s been shown to slow type 2 diabetes progression, Manoogian said.
Another 2025 study by scientists at the National Institutes of Health found that adults with obesity on TRE lost more weight compared to those who ate a Mediterranean diet. The TRE followers lost a similar amount of weight whether they restricted eating to an eight-hour window in the morning, afternoon, or self-chosen period. But those on a morning TRE plan lost more subcutaneous fat (stored in areas like the abdomen and buttocks) and had lower fasting blood sugar levels, the research showed.
How to Make TRE Fit Your Schedule
If you are considering TRE, speak with your doctor about its benefits and risks. Keep in mind that long-term health effects are still under investigation — a large study published in 2025 suggests that an eight-hour TRE schedule may carry some risks to cardiovascular health.
If your doctor agrees that TRE is safe to try, Manoogian recommends collaborating with them on a “personalized TRE” plan that takes into consideration your lifestyle and sleeping habits.
“The first thing we do [at our lab] is understand when you’re sleeping,” Manoogian said. She advises waiting one hour to eat after waking up and not eating for at least three hours before going to bed. You can drink water, black coffee, and unsweetened tea during fasting periods.
Next, she has people identify any “important meals,” such as family dinners. If your family eats together at 6 p.m., your eating window should end at 6:30 p.m. or later, whatever gives you enough time to participate. Work backward to determine the best window for you. For example, you could have a 10-hour eating window from 8:30 a.m. to 6:30 p.m. or a 12-hour eating window from 7:30 a.m. to 7:30 p.m.
“By doing it this way, you can make it fit anyone's schedule,” Manoogian said.
