“Have a drink, it’ll warm you up!” It’s freezing, and we make you this friendly proposition based on popular common sense: drinking a glass of alcohol would help you cope with the cold, we believe. Really ? Well no. This perception is in reality a pure illusion that our body plays on us: despite the impression of being warmer after consuming an alcoholic beverage, alcohol does not increase body temperature. And on the contrary, he can help bring it down! Explanations.
When it is cold, the body adapts to keep its heat stock available to the vital organs (heart, brain, lungs, etc.). To do this, it “forces” the superficial vessels to contract, on the surface of the skin and at the extremities of the body, including the hands, feet and ears. This therefore reduces the flow of blood to where it is “less needed”, to ensure that it is available in sufficient quantities to vital organs. This is called vasoconstriction, and this explains why we tend to feel very cold in the extremities of our body in winter. This thermoregulation mechanism is also shared by many mammals.
Let’s add alcohol to the equation. The immediate feeling is a small inflammation in the throat, then, more generally, hot flashes, sweating or even redness. A priori, so many witnesses to an increase in body temperature. However, this feeling of being hot is illusory. In reality, a mechanism opposite to that observed in the scenario without alcohol occurs: vasodilation of the vessels. “Under the effect of alcohol, the superficial vessels will tend to temporarily widen, which causes a greater influx of blood to the extremities and therefore an impression that our body temperature is increasing,” explains Bernard Basset, doctor and president from Addictions France.
The feeling, however, is very fleeting. After a few minutes, this vasodilation causes central heat loss. “The heat felt comes from the redistribution of blood towards the surface of the skin, which is to the detriment of vital organs,” emphasizes Dr Basset. Result ? Vital organs have difficulty maintaining their ideal operating temperature, and the heat that has reached the surface dissipates more easily. We’re even colder than before. So, contrary to popular belief, alcohol inhibits the body’s ability to detect and respond to temperature changes. If you drink too much, this can lead to prolonged exposure to the cold without being aware of it, and sometimes to hypothermia.
Also read: Our wise advice for resisting the cold (and avoiding some pitfalls)
A second mechanism is put in place with alcohol, which maintains our illusion of feeling less cold, and prevents the body from resisting. When it is cold, a natural source of heat is provided by shivering: by contracting to cause shivering, our muscles produce energy, which warms us. However, this mechanism can be bypassed by an unknown effect of alcohol on the liver. “By complex mechanisms, alcohol prevents the liver from producing sugar, which creates hypoglycemia. However, in the event of hypoglycemia, the muscles do not have enough nutrients immediately available to provide the necessary heat and therefore we warm up less by shivering,” explains Mickael Naasila, president of the French Society of Alcoholology and neurobiologist specializing in hypoglycemia. alcohol addiction at Inserm.
In addition to these two metabolic pathways, the effects of alcohol on body temperature will depend on other parameters, such as the dose ingested or the speed with which it is metabolized by the body. “Some people are more tolerant of alcohol than others, which means they assimilate it and eliminate it more quickly. This differs in particular with gender but also according to one’s drinking habits because the more one drinks, the more one’s tolerance threshold increases,” indicates Professor Naasila. These harmful effects of alcohol will also be exacerbated if the stomach is empty, hence the importance of eating well in preparation for a drunken evening. “It is important to remember that when the body does not have enough sources of energy provided by food, it will have to draw on its reserves. If you drink without eating, the risk of hypoglycemia is even greater,” adds Dr Basset. For some people suffering from chronic illnesses, particularly diabetes, alcohol is even more dangerous because it can contribute to increased blood sugar dysfunction.
For all these reasons, it is incorrect to attribute a “thermogenesis” function to alcohol. “This is a false belief and still too few people are aware of it,” insists Mickael Naasila. Specialists therefore urge vigilance, especially during cold spells. They remind us of the importance of dressing well in all circumstances and of ensuring that anyone who is heavily intoxicated at the end of the evening is accompanied home.
