I keep having to repeat this: in my experience, fasting and food quantity restriction is seriously prodromal for mania. And a good unrestricted euphoric mania can ruin your life.
Let us not forget that mood stabilizers are notorious for making you put on and retain weight. (Mine makes my body use its muscles for energy before it taps into my fat - hooray!) But honestly, lots of people with mood disorders - like mine, which prior to medication inspired me to periodically drop out of school and quit lucrative jobs - do that math every day. In the grand scheme of things, there are worse ways to be than overweight.
I fast for five to seven days a year plus intermittent fasting. In my experience it causes something close to a high. Elevated energy levels. A long fast allows you to change your guts flora which has a lasting effect on me. YMMV but n.b most cultures and religions include yearly fasting, and the is a lot of medical evidence that it's a good thing.