Or, he could just cut out processed sugar.
Re: “Or, he could just cut out processed sugar.”
That’s what makes the 24 hour fast so interesting.
When you try to restrict your caloric intake by just eating less food or less sugar, your body responds by converting almost everything you eat - including protein - into sugar.
Most likely, that response is a digestive artifact from our hunter-gatherer ancestors.
Every day tended to be feast or famine, and our digestive system optimally adapted itself to that reality.