You may have heard that cold weather makes you lose weight. In reality, as often happens with clichés related to health, this is not exactly the case. Several studies confirm that when we spend a lot of time in low-temperature environments, the body activates Brown Adipose Tissue (BAT) which increases energy expenditure using fat and glucose to produce heat (thermogenesis) and keep our body temperature constant. But it’s not enough for aeffective and visible weight loss. These studies could, however, provide new therapeutic targets and methodological strategies to be combined with a healthy diet and physical exercise. Let’s see how.
Cold increases energy expenditure
The idea that cold makes you lose weight starts from the assumption that, as recalled by the WHO, for a healthy weight loss you need to reduce the energy introduced with food (being in deficit caloric) and increase the body’s energy expenditure. Simply put, eat fewer calories and move more. Now, when it’s cold our body is forced to burn energy to keep your body temperature constant, and this increases energy expenditure even without having to get up from the couch. Think for example of shivering from the cold, which uses up a certain amount of energy to help keep your body temperature constant.
Although this topic has interested researchers since the 1970s, only recently (early 2000s) has research discovered how it could work. We should therefore point out that this is still a “very young” field of research in scientific terms, and for this reason there is a lack of solid literature that can allow us to give precise indications, but from the data currently available, exposure to the cold seems reduce fat mass and improve insulin resistance and lipid profile.
Brown Adipose Tissue Transforms Nutrients into Heat
This thermogenesis induced by cold is called non-shivering thermogenesis or NST, because it does not involve shivering, but activates the release of noradrenaline. This in turn activates Brown Adipose Tissue (BAT), which uses fatty acids and glucose (stored or free in the bloodstream) to produce heat.
It was thought that BAT was present only in newborns and children, until by chance, as often happens in science, it was discovered also in adults: in PET (positron emission tomography) scans of cancer patients, some brown spotssimilar to metastases, but too symmetrical and precise to be so. Only after analysis was it discovered that they were BAT.
It is a tissue located mainly in the cervical area, between the shoulder blades, around the kidneys and blood vessels and is characterized by the presence of mitochondriathe cell’s energy factories, also responsible for the brownish colorIt is precisely the mitochondria that make this tissue so special, because the fat defined as white does not have them and cannot consume energy.
This discovery, however, opens up an infinite new world of questions, such as: but don’t mitochondria only produce ATP? And how does brown adipose tissue use fatty acids? Let’s proceed in order. Since There is still much to study about BATit is not exactly clear how it works, but some key points have been established.
First, BAT activation increases mitochondrial activity and cellular respiration, increasing glucose consumption.
Second, BAT mitochondria are equipped with a protein, called UCP1, which is able to direct fatty acid metabolism towards heat production instead of ATP. It also appears to reduce inflammation induced by excess weight by releasing an anti-inflammatory molecule, maresin.
How cold and for how long?
On average we are talking about spending every day from 2 to 6 hours in environments at temperatures between 15°C and 18°C. To get results we should feel cold, but without “freezing”.
The effect depends on many factors which vary from person to person: from the quantity to the activity of BAT cells; from lifestyle to white adipose tissue that we have, which could act as an insulator and make us tolerate lower temperatures.
Another positive aspect would be that repeated exposure for short periods to low temperatures forces some cells to white fat, the inactive one, to produce mitochondria and to behave like brown fat. Again based on their color, these fat cells are called “beige”: not as active as the brown ones, but not as helpless as the white ones either.
Yes, but how much weight do you lose in the cold?
Here’s where the problem lies: With exposure to cold alone, weight loss is not noticeable. Of course, when brown adipose tissue is activated, our body’s energy expenditure increases, but the most flattering studies report an increase of 5% at most, or less than 20 kcal per day. Not much then.
But BAT is also activated by physical exercise, so as usual It is not a single strategy, a single food or drug that gives us the solution for a better life or a sculpted body, but always a synergy of healthy eating and an active lifestyle… and maybe even setting the thermostat a few degrees lower than usual could be an extra help.
What we can take home from this research is first of all a better understanding of how our body works, and furthermore BAT, UCP1 and the other molecules involved can represent targets for new therapeutic approaches in the treatment of obesity and other metabolic diseases.
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