Is sweating possible if surrounding temperature is below the body temperature? How the sweating occur due to the combustion of food?
Most people most of the time live in the environments that have lower temperatures than it is their normal body temperature (36-37 °C). And most people sweat sometimes at these temperatures.
In the summer, when it is 30 °C and you wear only swimming trunks, even light walking can make you sweat. The same can occur in the winter when the ambiental temperature drops below 0 °C and you wear warm clothes. This is because the muscles, when working, can generate more heat than you need and sweating is the way to get rid some of it.
When you eat food and the food is broken down to release energy, some of this energy will be released as heat. If the food generates more heat than your body needs, eating foods, especially ones high in protein, can make you sweat.
Some people get sweaty after eating certain spicy foods. This is called gustatory sweating, which is not related to food combustion, but it is a neurological phenomenon.
Capsaicin in red hot chili peppers can also trigger heat generation and sweating.
Drinking alcohol dilates the blood vessels in your skin, which results in increased flow of warm blood through your skin, which can signal the thermoreceptors in your skin to trigger sweating.