“Air conditioning is fattening because when cool, our appetite awakens,” said by Javier Sánchez Perona, a researcher at the Fat Institute of the Higher Council for Scientific Research in Spain, who 20 years ago, when surprised by the heat in Seville, made him study the link between temperature and appetite.

According to a report by CNN Portugal, the specialist is from the Basque Country, where the temperatures are much milder, which is why he noticed the difference when he arrived in the Andalusian capital.

Like him, most Sevillians did not have air conditioning – something difficult to imagine in one of the hottest cities in Europe. At the same time, Javier Perona noticed that the city seemed to have fewer overweight people at the time leading him to begin his research.

If there was an apparent cause-effect relationship in the fact that Seville is a hot city and there are few obese people, the evolution of the population suggests that this relationship does exist. Air conditioning has arrived in the city, while Andalusia has become the region with the highest obesity rate in Spain.

Javier Perona does not state that the manipulation of air temperature is the only cause of obesity, because he has not found any studies that specifically demonstrate this relationship. However, says the researcher, it is more likely that such a study does not exist “because probably no one has ever done it”.

“What has been scientifically proven is the relationship between temperature and appetite. The higher the temperature, the less the appetite. Thus, it seems obvious that if we live and eat with air conditioning, we will eat more and gain more weight”, said the graduate in Food Science and Technology in statements to El País.

“Thermal sedentary lifestyle”

It is what some experts have dubbed “thermal sedentary lifestyle”, an adoption of behaviours that make us move less because we do not want to leave an environment where the temperature is controlled.

This relationship between temperature and appetite is proven by multiple investigations. In 1963 a study carried out with rats concluded that the animals ate much less when exposed to higher temperatures. At 35 degrees they ate 10% of what they had eaten at 24 degrees, and at 40 degrees they stopped eating.

More enlightening is a study published by the University of Birmingham, in the United States, which showed that, every time the temperature increased by one degree, human beings ate 85.9 kilocalories less of the food they were given, in this case pizza.