Calories burn more quickly in the evening, according to new research

The number of calories that people burn while at rest are changing at hour time, according to a new study by Harvard Medical School.

The findings strengthen the important role of circadian clock in governmental metabolism. It also helps to explain why irregularities in diet and sleep schedules due to shift work or other factors can make people more likely to gain weight.

Kirsi-Marja Zitting, the lead author of the study, said: "The fact that we did the same thing once a day burned so much more calories than doing the same thing at a different time of day surprised us."

To determine changes during the day in metabolism in addition to the effects of activity, sleep-wake-up and nutrition cycles, researchers surveyed seven people in a special lab without any indication of when they were out. There were no clocks, windows, phones or the Internet. The participants in the study had given hours to go to bed and wake up. Every night, these times were adjusted four hours later, the equivalent of moving westward to four time zones each day for three weeks.

"This allowed us to measure the metabolic rate in all the different biological hours of the day," said Zitting.

Data showed that energy expenditure was higher in the afternoon until evening.

"It's not just what we eat, but when we eat – and rest – it affects how much energy is burned or stored as fat. The regularity of habits such as eating and sleeping is very important for general health. "