So, you'd starve a snake with poor muscle tone thin?
If you have hundreds of snakes you know better than allow them to get this way. Fix the husbandry issue that's causing the inactivity/poor muscle tone, then handle them to get them active again. If your husbandry is good, they will be active and you won't need to. Older snakes sometimes get fat and lazy (But not all of them.), same as people, but those snakes are eventually not fit for breeding because of poor muscle tone. They still make fine pets with proper care. If you know a snake is obese it's your fault it got this way. Handle him a few minutes a day, and it will be better soon.