Researchers found that when at rest, people burn 10 percent more calories in the late afternoon and early evening than in the early morning hours. The findings have been published in the journal Current Biology. They reinforce the important role of the circadian clock in governing metabolism. They also help to explain why irregularities in eating and sleeping schedules due to shift work or other factors may make people more likely to gain weight. "The fact that doing the same thing at one time of day burned so many more calories than doing the same thing at a different time of day surprised us," said lead author Kirsi-Marja Zitting of Harvard Medical School.
To determine changes over the course of the day in metabolism apart from the effects of activity, sleep-wake cycle, and diet, the researchers studied seven people in a special laboratory without any clues about what time it was outside. There were no clocks, windows, phones, or Internet. Study participants had assigned times to go to bed and wake up. Each night, those times were adjusted four hours later, the equivalent of traveling westward across four time zones each day for three weeks.
"Because they were doing the equivalent of circling the globe every week, their body's internal clock could not keep up, and so it oscillated at its own pace," co-author Jeanne Duffy explained. "This allowed us to measure metabolic rate at all different biological times of day." The researchers found that participants' respiratory quotient, which reflects macronutrient utilisation, varies by circadian phase, too. This measure was lowest in the evening and highest in the biological morning. "It is not only what we eat, but when we eat–and rest–that impacts how much energy we burn or store as fat," Duffy said. "Regularity of habits such as eating and sleeping is very important to overall health."
Foods That Boost Metabolism
1. Vitamin-D enriched foods: A deficiency of vitamin D can slower your metabolism. Sunlight is the most important source of Vitamin D but since most of the time we don't enough of it, we should try and supplement our daily dose of Vitamin D by including foods like fish, eggs, tofu, soya milk and mushrooms.
2. Natural coolers: According to a study, staying cool and hydrated can assist in maintaining a high rate of metabolism. Balancing bodily fluids is very essential in maintaining a healthy metabolic rate, hence, natural coolers like melon and cucumber can help in keeping you cool.
3. Milk and yogurt: Milk is a rich source of calcium and some of the recent studies hold that regular calcium intake can help the body metabolize fat efficiently. Yogurt is well known for being rich in probiotics, the good bacteria that helps in digestion and keeps you cool. Cottage cheese is rich in protein and it can help you build, maintain and repair muscles.
4. Green tea and coffee: According to a study that was published in the American Journal ofClinical Nutrition, men who consumed a combination of caffeine and green tea extracts burned more calories. Green tea is rich in antioxidants like polyphenols which have numerous health benefits and also aid in weight loss. Caffeine helps in warding off lethargy and can even increase your endurance during workouts. Green tea also contains a plant compound called EGCG that helps in burning fat.
5. Lentils and Whole Grains: Lentils are a great source of proteins, carbohydrates and fibre that helps in good digestion. The iron content facilitates the flow of oxygen throughout the body which further helps in boosting metabolism and energy production. Also, include whole grains in your diet as they require extra energy to break down and digest and help in burning fat.