My two cats are now about one year old. When we first got them, Roo in particular was quite skinny and didn't seem to put on much weight, so I fed them as much wet food as they would eat and made sure they always had lots of dry to graze on. They were inside only cats. Suddenly, we realised that Roo was quite fat. I started cutting back on their food in October and a month later we constructed an outdoor enclosure. Now they spend most of the day outside, so they are getting more exercise and not so bored, hence not eating as much. Now I am worried that Roo is not eating enough again! Although she has dropped the fat over about 5 months, I don't want her to lose any more. I have been mixing tuna with their cat food to try to entice them to eat more. Is this OK? Is there any danger of feeding tuna for extended times? How do I know if she is too light? I don't feel her ribs, so I know she's not too thin, but I don't want her to continue to lose weight. She never eats much, just grazes throughout the day.