>>40591498 (OP)if you stop eating entirely, your body assumes your are starving due to a famine and slows down your metabolism to keep you from dying.
If you want to burn your winter fat that you spent the bountiful summers storing away, you must convince your body it is winter.
Grains and sugary produce are gone, the plants have all died back, food must come from hunting now. (keto)
The temperature is cold but we are still active, so we cannot simply hibernate to preserve energy stores for emergencies, we must retain muscle mass and begin thermogenesis. (cold room exercise)
It's all pretty simple really. just imagine you're a caveman, humans as a wild animal.
What are the natural cycles your body would go through in that life, your biologically-thoroughly-evolutionarily-adapted, ecologically-intended life? Which parts of those cycles are not occurring due to your highly artificial life of modern conveniences? Add them back. Suddenly you're healthy.
High blood pressure due to retaining water from high salt intake? When's the last time you sweat, water-cooled chase ape? You'll lose a lot of salty water really quickly if you take a 2 hour jog in 96 degree noon day heat.
Ulcers and indigestion? When's the last time you ate a bush, ground-dwelling primate? Your ancestors spent a millenia or more selectively breeding brassicas to be the most compact, nutritionally complete, helicobacter-killing bush possible, then into a million flavor and texture varieties, and you still won't eat it because "vegetables are icky."
It's all incredibly obvious once you put it into that mindset.