Feeding adults is usually a very easy process if they have settled into their new enclosure.
Adults will generally eats larger sized rats or even small rabbits for some bigger species. Care must be taken not to over feed snakes after they are two years old. A fat snake is very unhealthy and can cause many health issues. Fatty liver disease is common in overweight snakes. A good muscle tone should be maintained.
If your snake starts to look round and bulging in the body it you need to reduce food size and/or feeding frequency. Adults can be few every 2-3 weeks depending on their condition and whether they will be used for breeding. Don’t be concerned if your adults don’t eat during the regular breeding season (May-Nov). Adults will often not want to eat during this period as they are more concerned with breeding activities (especially males).