Please answer only if you actually have knowledge of biochemistry and can give a scientific answer. Thanks.
that's because our body burns more fuel to keep the optimal body temperature of 36°. When the exterior is much colder than the interior the body needs to burn much more, our enzymes and pathways work at best at 36°. Part of the energy coming from the breakdown of glucose or fatty acids turns into heat (the brown adipose tissue is specialized in getting heat instead of ATP from glucose breakdown)
in winter the body use aerobic respiration which needs alot of ATP(energy),,this is why we eat alot>>