A new study led by Dr. Courtney Peterson from the University of Alabama at Birmingham shows that eating early in the day and then fasting for the rest of the day can improve blood sugar, lower blood pressure, and reduce stress in the body—even if people don’t change what they eat.
Intermittent fasting has already been shown to help with weight loss and better metabolism.
But it wasn’t clear whether the health benefits were just because people were eating less. Dr. Peterson wanted to find out if the timing of meals alone could improve health, even without cutting calories.
This small but carefully controlled study was the first to test a special kind of intermittent fasting in people called early time-restricted feeding, or eTRF.
This method involves eating within a 6-hour window early in the day and fasting for the remaining 18 hours. It’s designed to align eating with the body’s natural clock, known as the circadian rhythm, which controls when our bodies perform best.
The study involved eight men with prediabetes. They followed two meal schedules for five weeks each. In one schedule (eTRF), they ate breakfast between 6:30 and 8:30 a.m., ate all their meals within six hours, and finished dinner no later than 3 p.m.
In the other schedule, they ate meals spread across a typical 12-hour period, similar to the standard American meal pattern. Importantly, the men ate the exact same foods on both schedules, and researchers carefully tracked their food intake and meal timing.
The results were striking. On the eTRF schedule, the men had better insulin sensitivity—meaning their bodies processed blood sugar more effectively.
Their pancreases responded better to rising blood sugar levels, their blood pressure dropped, and they had less oxidative stress (a type of damage caused by unstable molecules in the body). They also felt less hungry in the evening.
This study is important because it proves for the first time in humans that intermittent fasting has health benefits beyond simply eating fewer calories. It shows that when you eat may be just as important as what you eat.
Dr. Peterson and her research partner Dr. Eric Ravussin believe these findings highlight how important it is to eat in sync with the body’s natural rhythms.
They explained that eating late in the day can negatively affect metabolism, while eating earlier can support better health. For example, our ability to control blood sugar is strongest in the morning, so eating most of our food earlier in the day may be more beneficial.
The researchers hope their findings will lead to better ways to prevent diseases like type 2 diabetes and high blood pressure. They also believe that more research is needed to learn how meal timing can improve health and to find fasting routines that are realistic for everyday life.
If you care about nutrition, please read studies about A guide to diet choices for healthy kidneys and findings of Scientists find why limiting calories in diet could boost healthy aging and muscles.
For more about nutrition, please read studies about This nutrient in diet can prevent inflammation in older people and findings of Diet high in protein, zinc and niacin may protect heart health during weight loss.
The study is published in Cell Metabolism.
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