FEED THE FURNACE
No clothing (without batteries in it) is actually going to create heat for you, so we’re reliant on the chemical processes of our bodies to keep us warm. Key to that is energy – which means food.
In winter you’ll burn far more calories trying to generate heat than you will in summer, so you need to pack in a good balanced diet of complex carbohydrates, fat and protein. Cereals, rice, potatoes, brown bread and fruit are all good carb sources to give a quick energy boost. Protein and fat help with a slower energy release and keep your metabolism firing to create heat.
Drink warm (not hot) drinks. A study in 2012 suggested that ingesting a hot drink can trigger a sweat response, and the cooling effect of that sweat can outweigh any heat-energy you get from the drink itself. A warm drink will be less likely to trigger sweating or trick your body core in to thinking it’s warm.
Bear in mind that cold weather diminishes your body’s thirst response, so you may feel like drinking less water in winter. But this is a big mistake –
keep hydrated so your body can fire on all cylinders and break down food into energy.