“Time-restricted eating is not just about shrinking the eating window; it is about placing that window in the right part of the biological day,” Dr. Muhammad Usama, a triple board-certified sleep and obesity medicine physician, told The Epoch Times.
Why Timing Matters
“Early time-restricted eating is generally more metabolically favorable than late time-restricted eating,” Usama said. Skipping dinner, or finishing it earlier, aligns better with circadian biology because insulin sensitivity, glucose handling, and diet-induced thermogenesis (the energy burned during digestion) are all stronger earlier in the day, he added.
“Skipping breakfast and eating late may still reduce calories for some people, but metabolically it is often swimming against the body clock,” Usama said.
The Biology of Eating Earlier
Why does eating earlier seem to work better? The answer lies in chrononutrition—the study of how meal timing interacts with the body’s circadian rhythm.
A master clock in the brain synchronizes clocks throughout the body, including those in the liver, gut, pancreas, and fat tissue, that help regulate metabolism. As a result, when we eat can influence how efficiently our bodies process food.
Glucose tolerance naturally peaks in the morning after the overnight fast and declines as the day goes on, so the morning is a good time to eat and metabolize food.
Additionally, GLP-1 hormones, which trigger insulin response, are naturally higher in the morning.
“The same meal eaten at 8 a.m. and 9 p.m. is not the same metabolic event,” Usama said.
Who Should Be More Careful
Although eating in line with your body’s natural rhythms can benefit most people, women—particularly those managing insulin resistance, polyendocrine metabolic ovarian syndrome, or perimenopause—may have even more at stake.
Mpho Tshukudu, a functional nutritionist, recommends a protein-rich breakfast, a substantial lunch, and a light, early dinner for this group. A protein-rich breakfast helps stabilize blood sugar after the overnight fast while also helping to moderate the natural morning rise in cortisol.
Skipping breakfast, by contrast, places extra stress on the hypothalamic-pituitary-adrenal axis, the body’s main stress-response system, and reproductive hormones over time.
“Women are generally more sensitive to energy restriction because of the way stress and reproductive hormones interact,” she told The Epoch Times.
Children, pregnant or breastfeeding women, people with a history of eating disorders, and those taking glucose-lowering medication should seek professional advice before fasting.
“Most importantly, timing cannot compensate for a poor-quality diet,” Tshukudu said. It is better, she added, to eat a healthy breakfast within a sensible fasting window than to extend a fast—only to break it with an unhealthy meal.
An Ancient Perspective on Meal Timing
The idea of eating in tune with the body’s natural rhythms isn’t new. Traditional Chinese medicine, a centuries-old healing framework, reaches a similar conclusion, though through a different lens.
According to TCM, stomach energy is at its peak between 7 a.m. and 9 a.m.—the ideal time to eat breakfast. A warm, nourishing meal is believed to provide fuel for the body and support steady energy throughout the day.
Because evenings are considered a time for the body to wind down, TCM favors eating a lighter, more modest dinner to avoid placing unnecessary strain on digestion before sleep.
The frameworks differ—one draws on circadian biology research, the other on a traditional medical system—but both point the same direction.
“I see time-restricted eating less as magic fasting and more as metabolic alignment,” Usama said. “It works best when it helps people eat during the hours when the body is biologically better prepared to handle food.”
