During the sweaty, sticky, dog days of summer, you may notice that you’re not as hungry as the cooler weather. But what is the relationship between temperature and appetite? Why do we feel less hungry when it’s hot?
The influence of temperature with appetite has long been noticed by scientists. “What we do know is that people in colder climates eat more calories,” Allison Childressregistered dietitian and associate professor at Texas Tech University, told Live Science.
There is a basic biological reason for this. Calories it is a part of power; burning them can release heat, helping people maintain their body temperature in very cold climates. But as winter warms up, “people realize they’re less hungry” — a trend Childress has seen in her clinical practice. in the extensive scientific literature.
However, the mechanisms behind this phenomenon are unclear. Many factors influence caloric intake, Childress said.
Matt Carter, a neuroscientist at Williams College in Massachusetts, agreed. Many variables — including hormones, proteins and environmental factors — affect why we’re hungry, and ultimately, why those feelings decrease on hot days, Carter said.
Related: What is the hottest temperature the human body can withstand?
Our body is always trying to keep internal conditions stable. This is called homeostasis. That’s why we sweat on a hot day or drink water after a vigorous workout. Hunger is also homeostatic; we feel hungry when our body is low in calories and we feel full after eating, to maintain our internal body balance.
Many homeostatic processes are maintained by hormones, which act as chemical messengers in the body. In appetite and satiety, two hormones play a major role: ghrelinwhich is aborted when it is empty, and leptinwhich is produced by fat cells and tells the brain when the body is full.
To influence our emotions and behavior, these hormones signal the hypothalamus, which is the part of the brain that works to control aspects such as body temperature, hunger and thirst. At the base of the hypothalamus is a cluster of specialized neurons that “regulate feelings of hunger and hunger,” Carter said. There, ghrelin stimulates hunger-related neurons, called AgRP neurons, making you feel hungry. Leptin, in turn, inhibits these neurons and stimulates POMC neurons, which make you feel full.
But how temperature affects this complex system “is still an open area of research,” Carter said. The brain has sensors for temperature – proteins that change shape once your body hits a certain temperature level. A study published in a journal eLife in 2020 found that in mice, certain brain cells send information to AgRP neurons when the temperature is cold, which increases feelings of hunger.
On the other hand, when it’s hot, POMC neurons contain a heat-sensing protein that kicks in when the body’s temperature increases, then activates neurons associated with the fullness, according to a 2018 study in the journal. PLoS Biology.
“But perhaps there is more to it than that,” said Carter; Other brain circuits may also work together to influence how much we eat.
Childress also notes that there are other reasons. “While we still have these natural processes and heat and cold, it’s also important to know that we can eat these natural processes,” he said. Sometimes we lose that ability to listen to our body – for example, we eat more when we are full or we don’t eat when we are hungry.
Regardless of the symptoms, Childress noted that in the summer, it’s important to stay hydrated, whether it’s eating water-rich foods like vegetables and fruits or drinking water. Conversely, frozen foods can increase body temperature because they are usually high in calories.
Hot or not, appetite is a complex balance – the way our body adapts to the environment. “Eating and drinking are things that seem to happen naturally,” Carter said. “But actually, behind the scenes, the brain correctly calculates the need for calories, for water, for the correct body temperature. And I think it’s amazing.”
#feel #hungry #hot