A lot of my snakes can gain 100 grams a month no problem, no matter their age. I feed rats and feed appropriately sized rats at that. I feed about once a week now cus my schedule is terrible. But when I had more free time for the snakes I was feeding ALL my snakes every 3-5 days. If they eat great, if not it's ok. I have never had an "obese" ball python. Instead I have had balls with some good girth on them, which helps for egg laying. I have personally never had an issue whatsoever.

Now back to someone talking about the feeders eating each other. I have only had them eat each other on the way the home if they are dehydrated or hungry. For the most part they will be fine for a while. Heck when we would put away the feeders that didn't get eaten, we hardly saw acts of cannibalism. But I have seen rats eats rats (they usually eat the smaller ones, fuzzies, crawlers), I have seen mice eat fuzzy rats, and I have seen rats eat mice.