During the summer months, they may eat more frequently than in winter. If they don't want to eat, they won't eat. It may be possible to over-feed some snakes and see them get obese, but I think it's far more common to see some owners under-feed their animals. If they are healthy and have a proper environment they should want to eat very regularly (once a week) especially during the warm spring and summer months. If you watch them closely you may even notice behavior clues that say "I'm hungry". Mine usually move around as if they are "on the hunt" when its about time for a feeding.
My Coastal Carpets eat one very large, jumbo rat once a week during the summer. It's easy to let time pass and skip feeding them, so I make it a very regular habit to feed them every week during the summer. One way to make this a habit is to designate a particular day as "snake feeding day". I usually do all my feeding on Sunday. Mine usually eat well, but there are occasional times when they won't eat and that's alright but best not to go for long periods without feeding.
Sounds to me like maybe you could improve your temperature. You should try to maintain a proper temperature gradient. Although certain types of carpet pythons are more tolerant of a broader temperature range, I believe that Jungle Carpets are one that prefer to have a warmer temp (someone can correct me if I'm wrong about that). In nature, JCP live in a warmer climate that others like diamond carpets. They should have a temperature gradient with one end of the enclosure warmer (85-90 degrees) and the other end not so warm (75-80 degrees) so that they have a choice of temperatures to thermo-regulate. A warmer temperature is also valuable to them when they are feeding well. Mine usually bask, fat and happy, in their warmest spot after feeding. If the snakes are simply too cold it can effect the digestion of their food items. But you want to set up a proper heat source and not have it directly exposed to the snakes so they can't burn themselves if they touch it. I use ceramic heat lamps that are placed on one end of the enclosure and separated from the snake by a piece of metal screen. The heat source is about 3 feet above the floor of the enclosure. This spot, under the heat lamp, is where my snakes spend a lot of time.
On a related note, I took in an adopted ball python that was badly neglected and was very underweight. I focused on feeding him as much as he would eat, and on providing him a very proper temperature gradient, and he is now a beautiful, robust snake. It took several months to really see his weight come up to what it should be, but it's a pleasure to see him healthy now.
Good luck!
Hayseed
1.1 Coastal Carpets
1.3 Corn Snakes
1.0 Ball Python
2.2 Leopard Geckos
