New clue in battle of the bulge
THE body burns more kilojoules in the early evening when you have your feet up on the couch than at other times of the day when you're at rest.
The surprise findings from Harvard University scientists highlights that it's not just what you eat, but when you eat, that is important, and puts a question mark over the idea that eating at night piles on the kilos.
When at rest, people burn 10 per cent more kilojoules in the late afternoon and early evening than in the early morning.
The research, published today in Current Biology, is a small but important US study that highlights the vital role of the circadian clock in governing metabolism.
It comes from the Division of Sleep and Circadian Disorders at Brigham and Women's Hospital and Harvard Medical School.
Lead author Kirsi-Marja Zitting said: "The fact that doing the same thing at one time burned so many more calories than doing the same thing at a different time surprised us."
Co-author Jeanne Duffy added: "It is not only what we eat, but when we eat and rest that impacts how much energy we burn or store as fat.
"Regularity of habits such as eating and sleeping is very important to overall health."
Brisbane registered nutritionist Katie King said she didn't believe "a calorie is a calorie" and was worth the same no matter when consumed.
"Just because two types of food have the same calories does not mean that they will impact the metabolism in the same way," she said.
"I think it is feasible that the body at rest will behave differently at different times of the day."
The diet expert said hormones played a big role in how the body operated, especially cortisol, the main stress regulator.
"Cortisol levels will be low in the morning, and perhaps higher later in the day if the day has been stressful or overly busy," she said.