It's normal to lose weight after a large defecation, as obviously they'd lose the weight of the feces. The real question should be whether he's losing weight after taking the feces into account, i.e. does he weigh less empty now than he weighed empty before? It's important to do an apples to apples comparison.

At 288g empty, which is the real weight, you should not be feeding anything near a medium rat. A weanling rat would be much more appropriately sized.

Give your snake a long break before its next meal, as you've been way overfeeding him, so that he has time to catch up. Definitely wait until the next defecation if he's eaten since the last time, and then maybe another week after that. He's also approaching the age where you can start slowing down feedings in general, if he doesn't slow down on his own. My 2016's would gladly continue eating every week, but I've slowed them down to every other week already, as I was noticing they were a bit more pudgy and less toned/muscular than I thought they could be. They're still growing like weeds fed less often. Growing up ball pythons isn't a race, or at least shouldn't be.

Quote Originally Posted by Deborah View Post
By feeding large prey you will end up with an animal that will not feed with consistency and that is overfed.
This is not necessarily a bad thing. Consistency in feeding is not natural for ball pythons, which are binge feeders in the wild. They'll go into a rodent burrow, eat multiple prey items at once, and then just sit there until another rodent comes in, which they will eat also. Then, after they've fully digested and defecated, they'll move on in search for another burrow with rodents inside. They're not such effective hunters that they're able to accomplish this immediately either, so it can take a while to find the next meal(s).

Given what's now known about organ remodelling in most boids, it's likely that larger meals less often more similar to their feeding habits in the wild is likely preferable to smaller meals more often. The benefits in doing so (e.g. effect on longevity) may take 30+ years to demonstrate, assuming someone actually gathers the data of snakes fed one way vs the other. Ball pythons are so forgiving that it's hard to tell in the short term either way, as they can be successfully kept and bred either way, although slug rates or breeding related issues or fatalities could perhaps be measured.

In more challenging species, more success is usually had when husbandry better approximates conditions in the wild (minus of course more obvious threats like predators). So presumably, there should be similar benefits with ball pythons also even if these benefits are not noticeable in the short term.