If only because the accelerated metabolism harms the entire body. The first to suffer is the heart and the vascular system. Behind it is the nervous system, digestion and further along the chain. So for those who want to lose weight and stay healthy at the same time, the best way so far is to go on a diet and count calories.
Why don't they use it? They even use drugs that directly increase the basal metabolism, namely the hormone thyroxine. But the problem is that it all works while the drug is being used. When it is canceled, everything returns to the starting point, and you will not take increased doses of thyroxine all your life. Diet and exercise work well on an ongoing basis.
How can you constantly increase your body temperature? Is there a pencil around the clock?) And not far from poisoning. Unless there is some kind of chronic disease that will give subfebrile temperature. The increase in t outside was written above
Ummm ... Why not? For example, a sauna after exercise is a "classic of the genre".
But there is still such a moment. In order for the body to begin to "burn reserves", it must be adjusted to it. Only after 20-25 minutes of running do fat begin to be consumed. So, just warming yourself up with external heat sources is not the most effective way))).