Thermal sedentary lifestyle: the reason why air conditioning makes you fat

The researcher at the CSIC Fat Institute Javier Sánchez Perona is clear about it: "Air conditioning makes you fat because being cool makes us hungry," he says in an entry on his blog malnutridos.com, in which he begins by wondering precisely that " Does air conditioning make you fat?

In his blog, Sánchez Perona explains that when he arrived in Seville to work at the Fat Institute more than twenty years ago from Mondragón, his native Gipuzkoa, he was surprised by the heat of the Andalusian capital and how it reduced the appetite of the.

He says that then he, like most Sevillians, did not have air conditioning.

And this researcher from the Department of Food and Health also explains that he thought that this could be one of the reasons why there were few overweight people in Seville.

Years passed,

air conditioning became popular, and Andalusia became the Spanish region with the highest rate of obesity.

Is it a coincidence or are these two events related?

"I have not found any study that specifically demonstrates a cause/effect relationship between the increased use of air conditioning and the increase in obesity, probably because it has not been done," says Sánchez Perona.

“What is scientifically proven is the relationship between temperature and appetite.

The higher the temperature, the less appetite.

So it seems obvious that if we live, and eat, with air conditioning, we will eat more and get fatter."

"It is evidence that when you eat with a cooler temperature, you eat more," explains María José Castro, a medical specialist in nutrition at the University of Valladolid.

“The body at rest has a certain energy expenditure, what we call basal energy rate.

And human beings are homeothermic;

that means that we have the ability to regulate our metabolism to maintain a constant body temperature regardless of the temperature of the environment.

And what the body uses to produce that energy that keeps it at a constant temperature is food,” she adds.

This relationship between temperature and appetite has been proven with multiple investigations.

Already in 1963, a study carried out with rats showed that, exposed to a temperature of 35 °C, the animals ate only 10% of what they had consumed at 24 °C.

And at 40 ° C they stopped eating completely.

But not only rats eat less with heat.

Another 2015 investigation carried out at the University of Birmingham (USA) showed that for each degree increase in ambient temperature, the study participants, this time humans, ate 85.9 kcal less of the food they were given in the study (pizza).

But if, as Sánchez Perona explains, there are no studies specifically focused on showing that air conditioning makes us fat, what there is is research that proves that living in an environment with little variable temperatures does make you gain weight.

And those little variable temperatures in which more and more people live, we achieve them with air conditioning in summer and heating in winter.

These two magnificent inventions give us what has been called "thermal sedentary lifestyle".

A study published in 2014 by researchers also from the University of Birmingham concludes that “with the widespread adoption of climate control, humans are protected from extreme temperatures and spend more and more time in a thermally comfortable state in which stresses are minimized. energy demands”.

That is, since we are less hot and less cold, we need less energy to maintain the constant temperature of our bodies.

And for this reason, this study concludes, "the time spent in that

zone could contribute to greater energy efficiency with a decrease in the metabolic rate and a consequent weight gain".

The question is of pure logic: if we eat the same, but our body spends less, that excess food becomes extra kilos.

All these studies are related to the interest of scientists to unmask the causes of the so-called obesity epidemic that is spreading throughout the world.

Because what is evident is that since that epidemic began to grow, human genetics has not changed, so the cause must be in the environment.

For a long time, the two big ones were accused: the growing consumption of food, including processed and ultra-processed foods, and a sedentary lifestyle.

But many people in the scientific world believed that there must be more reasons.

And little by little some are revealed.

The massive abandonment of tobacco, which has been so beneficial to combat cancer, has, however, this negative side of favoring the increase in obesity rates.

Also the increasing consumption of some drugs, including antidepressants, contraceptives and antihistamines, seem to influence them.

All together, together with the two big ones and the constant and comfortable air conditioning in which we live, more and more people make our lives easier, and apparently fatter.

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