Is a Combined Calorie- and Time-Restricted Diet Best?
The trial recruited 139 Chinese adults (ages 18 to 75) in free living conditions and randomized them to either the time/calorie-restricted diet or the calorie-restricted diet alone. The extent of caloric limits were sex-specific: a diet consisting of 1,500-1,800 kcal per day for men and 1,200-1,500 kcal per day for women. For the 69 participants randomized to the time-restricted group, they could consume the same amount of calories but only between 8:00 a.m. and 4:00 p.m. Outside of this window, only noncaloric beverages were permitted.

All had obesity, defined as a BMI between 28 and 45. Some exclusion criteria included chronic viral hepatitis, malignant tumors, diabetes, serious liver dysfunction or chronic kidney disease, current smoking, and either serious cardiovascular or cerebrovascular disease.

Both diets appeared to be safe, with no deaths or serious adverse events reported in either group. There was a similar rate of mild adverse events among both diet types, which included fatigue, dizziness, headache, decreased appetite, upper abdominal pain, dyspepsia, and constipation.

Men and women in both intervention groups also adhered to the same caloric restrictions: consuming a combination of 40% to 55% of calories from carbohydrates, 15% to 20% from protein, and 20% to 30% from fat. This diet accounted for about 75% of the participants' baseline daily caloric intake.