Does Your Metabolic Rate Change According to the Time?

Does Your Metabolic Rate Change According to the Time?

A group of researchers has concluded that the metabolic rate of a person does not stay the same for the whole day. Instead, it goes up and down- and might go up even if a person is sitting on a couch doing nothing. This shows that the energy-burning ability of a person can fluctuate across the day.

A recent study shows that a person’s metabolism does not stay the same for 24 hours — in fact, there are times of the day where their body is chewing through a greater number of calories while they are just sitting there.

During a morning time, watching the sunrise, a person may feel like he is not burning any calories and similarly, in the evening after a long office day, sitting on the couch watching TV, he may feel like he’s not burning any calories, but science states otherwise.

Research states that the person will start burning 10 percent more energy later in the day as compared to that at the start of the day. That means that the body will start burning up more and more nutrients as the day passes by.

This goes against the commonly held belief that our bodies metabolize very slowly in the evening. Everyone is burning up calories every time, whether he is in the state of sleep or wakefulness. The body is always in need of energy and will function accordingly to fulfill its needs. These needs don’t depend on whether the body is at sleep, rest, or slightly working.

Effect of Isolation

To see how our internal-combustion system works, researchers had to free people from the bounds of the world. Seven participants were chosen for the study and each one of them were given consent forms to ensure they were there on their own will. The setting of the experiment had to be in such a way that participants couldn’t know what time or date it was.

To achieve this goal, they had to place the subjects under a situation that had no internet, windows, clock, or phones. This ensured that the time, either dawn or dusk, had no influence on the internal combustion system of the body.

Every person was assigned a time to go to bed and to wake up. Although this felt like living in a terrorist jail cell, applaud goes to the participants who would give anything for science. The study went for 3 weeks and the schedule for their wake-sleep cycle was rotated every four hours.

This rotation was equivalent to circling a globe every week as researchers had to make sure that the time had no effect on the metabolic rate of a body. The four-hour rotation ensured that scientists saw every little detail that how the body’s metabolic rate changes when the wake-sleep cycle is changed.

As the body was unable to start a rhythm of the wake-sleep cycle, it had to develop a new pattern. Participants waking and sleeping at different times ensured that their bodies were not getting used to a rhythmic metabolism. The results of this experiment gave scientists the detail of how the body would perform around a clock even if there wasn’t a rhythm.

The results were astounding. It was something that most people never knew. The results showed that the metabolic rate of a person was slowest during their biological night meaning the metabolism of a normal person would be lowest at night. This shows that eating late at night is harmful to the body as the enzymes used for digesting that food are already sleeping.

Does Your Metabolic Rate Change According to the Time?
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However, the metabolism was highest just after 12 hours of waking up. For a normal person, this shows that the metabolism is at the peak during the afternoon and evening time. The fact comes as a surprise due to the fact the people didn’t know earlier that doing the same thing over different times of the day would burn different calories.
For example, if you were doing your regular work at the morning, versus you were doing that same regular work at the noon, then obviously you would be burning up more calories at the noontime compared to that of the morning.

The lead author, Kirsi-Marja Zitting of the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital and Harvard Medical School, both in Boston, MA, told in an interview that the research would help people change their lifestyles for a better quality of life. This can help people with obesity and those who are demotivated for running or gym.

Calories being Burnt Continually

Humans are like a never stopping engine. They burn calories every time every day nonstop, from the day they are born to the time they die. People are regularly burning calories whether they are laying down, running a marathon, walking across the office or a block, or even when they are sleeping.

Calories are in taken through various foods and drink we eat over the day. These calories are then used up our digestive system to digest the foods and then, in turn, produce more calories. These calories are burnt to help us with breathing, and various other bodily functions. The more a person moves, the more calories are burnt.

Calorie intake and calorie burning are the two most important determinants that people use to check if their overall intake of calories is increasing or decreasing. The people who are into weight loss are usually seen calculating their intake of calories. If their intake of calories is increased, this would mean that their weight is on the rise- which is correct most of the time. These people should take into note this research while calculating their overall increase or decrease in calories.

What Does this Indicate?

Everyone has his own basal metabolic rate (abbreviated as BMR). Basal metabolic rate indicates how much a person is burning calories at rest. This also indicates that how much energy is burnt by a person who is not actively participating in physical exertion.

This study reveals how much BMR of a person will fluctuate in 24 hours. As this study indicates that our bodies use the most energy during the morning to noontime, this could show that it’s a rather good idea to make lunch the biggest meal of the day. Usually, people prefer making dinner as the biggest meal of the day, but now it would be better if people switch this to lunch.

Jeanne Duffy, also in the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital has mentioned that it is not important what people eat, but it’s more important when they eat and when they rest.

This can have a much larger impact on how much energy our bodies store as fat and how much it burns away. All in all, regulation of habits, such as eating and sleeping is one of the biggest factors to the overall increase in health.

This team of researchers is now planning to study how appetite and the response of body towards food differ according to the time of the day. These scientists would also research deeper into how the duration and the frequency of sleep can affect a person’s response to food and weight gain.


Nancy Walker

Nancy holds a Medicine degree and a Masters of Science MS in Infectious Disease and Global Health (MS-IDGH) from Tufts University. She worked as a lecturer for three years before she turned towards medical writing. Her area of interest are infectious diseases; causes, mechanism, diagnosis, treatments and prevention strategies. Most of her writings ensure an easy understanding of uncommon diseases.

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