The Scientific Connection Between Body Heat and Metabolism

It's commonly believed that you burn more body fat when you get hotter. We look at the research to determine whether this is fact or fiction.

What is metabolism and body temperature?

Metabolism refers to your body's ability to make energy from food and fat stores. The higher your metabolism level, the more fat you will naturally burn. People with high metabolisms often have lower body fat percentages. People with low metabolisms have less energy and struggle to lose fat mass.

Body temperature (also referred to as core temperature) is the overall temperature within your body. Being too hot or too cold is dangerous, so your body tries to keep it within a healthy balance (from 97 - 99 degrees Fahrenheit or 36.1 - 37.2 degrees Celsius).  A single shift upward or downwards of a single degree has significant health implications. Some people have a higher natural body temperature than others (We are covering whether this is related to metabolism). The environment, physical activity and general health play a role in your current body temperature. 

Reasons why people might believe that temperature affects your metabolic rate

Before we get into whether this is true or not, I want to list the most popular reasons why people believe that increasing your body temperature will burn fat.

Exercise makes you hot

Exercise raises your core temperature and burns fat. Many believe that you can determine how much fat you are burning during exercise by how hot the exercise is making you.

You can sweat fat away

Commercials have sold products that make specific parts of your body sweat, based on the premise that heat melts fat away. Many people use steam rooms in an attempt to lose weight. Others suggest that fat is one of the things that makes up sweat deposits. It is often assumed that sweating can help you achieve a better looking body.

Heat makes your body more active

Another theory is that heat increases bodily activity, and that this increased activity uses energy from fat.

Natural instinct

People notion the fact that your body will instinctively want to store up energy in the form of fat when the environment is cold (the hibernation effect) as a primal instinct. This notion will also stipulate that people will have more energy (and therefore a higher metabolism) when it is warmer.

The science: Is metabolism is affected by body temperature, and is body temperature affected by metabolism?

Higher body temperatures burn more calories

Fitday.com quotes a report by the American Clinical and Climatological Association. This report showed that higher body temperatures do indeed increase metabolism (or metabolic rates) within the body. This study provides evidence that you can burn 10 - 13% more calories for every 1 degree Celsius that your body temperature is elevated.  It is important to note that this is calculated regarding internal body temperature, not your environmental surroundings. 

Fit day says that this could mean that you would burn 100 to 130 extra calories per day, per degree by which your body is heated up. This is calculated on the estimate that you burn an average of 2000 calories per day, divided by two. The amount is divided by two because body temperature accounts for about half of your total caloric expenditure.

Low body temperatures burn less calories

The same study also showed that the opposite is true. It said that each drop in body temperature (calculated by degrees Celsius) decreased caloric expenditure by the same amount (10-13% of energy burned).

External factors: Cool environments burn fat

Cooler external environments cause the body to burn more calories to maintain the right core temperature. This is according to the National Institute of Health's research on how cool temperatures alter human fat and metabolism. The researches exposed men to cooler environments for a month to study the effects. They found that these men had higher metabolic rates than before. It appears that their bodies became better at burning calories to maintain optimal body heat. It was almost like their bodies were being trained to use more calories in a similar way that exercise trains muscles to perform better at doing a certain task.

External factors: Hot temperatures burn fat too

Another study measured the calories burned by people who exercised in different temperatures. The people who performed physical exercise at higher temperatures burned more calories than those who worked out at lower temps. The people who exercised in warmer surroundings burned more calories because their bodies had to spend more energy to cool them down. 

How can low and high external temperatures burn more calories?

It seems that energy expenditure boils down to the difference between what your bodily systems want and the external challenges that they are currently facing. Your body burns calories to warm itself up when it is feeling too cold. It also burns calories to cool itself down when it feels too hot. 

Therefore, the greater the challenge that the body faces in regulating body temperature, the more calories that it burns in order to do so. The effects on calories burned and overall metabolism are both immediate and gradual. Your body will use more calories during the exact time that it needs to regulate internal heat (or lack thereof) more intensely. When it needs to regulate temperature more often, it adapts by becoming better at opening fat cells for energy, which improves over metabolism.

Thermal weight loss: How to use heat to burn fat

Don't be scared to let your body regulate heat by itself sometimes

Compensating for the weather or environmental factors by adjusting the air conditioner and layers of clothing could be hampering your body's self-regulatory mechanisms. The more they are used, the better they become at tapping into fat to regulate themselves. In nature, our bodies had to face the usual increases and decreases in temperature without all the vices that we have today.

Don't overdo it

The trick is not to shock your system by sharply changing the surrounding warmth all at once. Gradually adjust it up or down to allow your body to naturally adapt. Dropping temperatures too low can cause hypothermia, which can have serious health risks. Also, increasing the temperature too quickly can lead to hyperthermia. Hypothermia and hyperthermia can both cause a variety of health problems. Gradually experimenting with different temperatures to stimulate your metabolism over time will give you better long-term results, just like how exercise should start off easy and increase in difficulty as your body adjusts.

There are times when you shouldn't use thermal weight loss techniques at all

As much as playing with the thermostat sounds more beneficial than ever, you should not try this if your body is already challenged. For example, exercising in hotter temperatures will decrease physical performance because your body will need to dedicate more energy to regulate itself. Sleeping in rooms that are too cold can disturb your sleep cycle and reduce sleep quality. Keep your body at the most comfortable heat when you are sick or feeling ill. It needs all the energy that it can get to recover. STAY STRONG!

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