Are there any statistics / findings on obesity rates in strictly indoor cats as compared to outdoor cats? Does giving a mostly indoor cat some time outside often result in noticeable weight loss?
That's a really interesting question. Here's what I found online. https://www.friendshiphospital.com/friendship-news/cats-indoor-versus-outdoor/ :
As a result, outdoor cats have a lower risk of obesity and stress related disease processes such as Feline Idiopathic Cystitis, among others. Despite these benefits, most studies have demonstrated that urban cats who remain indoors can live up to 2 years longer than their outdoor counterparts.
I couldn't find any specific studies, but I hope that helps with part of your question.
I am not sure about any specific statistic or method, but there are some facts through which we can get some points regarding this.
I have assumed that: From Indoor cats, you mean the cats which we keep with us, and don't let them go outside. And From Outdoor cats, you mean the cats which we keep with is but let them go outside, to spend some time there.
This can be the reason because at home, cats got limited and same place. That is why, they simply less explore and walk as compare to outdoor cats. That's why they are slightly obese than those.
Cats feel safe when they are at home, but at the same time, some wants to go outside (just to visit or explore) but when they are tired, they come back to home for relaxation. That is another reason, that cats don't feel safe outside so they don't sleep or take rest there. So this activity is considered as extra as compare to the indoor cats.
It is believed that the outdoor cats, which we keep with us are more active and healthy as compare to the indoor cats. Because they have observed and seen multiple environments and are aware of.
@akuminari has also catch the correct point, that the outdoor cats have low risk of obesity and stress. Most of the internal function and system of cats are similar to human. Like: loving nature, attract to those who care, digestive system, they are having emotions, etc. The scale of sensitivity is different!
So for healthy, stress less, active, and normal weighted human some visits, activities etc are necessary. The same case is with cats.
I have shared such views, based on my experience. I had two cats, one was indoor and other was outdoor. I have personally felt that outdoor cat was not obese as compare to indoor one. And outdoor cat was more active than other one.
You may feel some difference in the weight when you decide to go out with your cat in few months or weeks.
Hope this will help you!