I have noticed my cat about 5 yrs old, start to bulk up, wanting more food and increasing weight that seems to go to muscle (btw she is spayed). This seems to coincide to visitations into her territory by 2 other cats, one male (neutered) and another unknown status or gender.
Is there any evidence that such a gain may be caused by territorial threats?
Could be. Territorial threats are known to cause stress in cats, and stress often leads to overeating.
I suspect your cat’s internal dialogue is not so much, 'The enemy approaches, must bulk up to defeat them" but more likely, 'Oh crap, invaders outside, must eat all the food so they don’t get it."
Or what t-bonham@scc.net suggested. Your cat is stressed, and stress causes overeating. Happens to me, too.
Yeah, evolutionarily speaking a ‘fatter’ cat would be ***less ***of a threat, not more. They’re slower & much less agile. Cats are ninjas, not sumos!