With dogs the link is more obvious. Or rather, without any further research on my part, the link seems obvious. If you have a bit extra on your plate, or a biscuit with your tea, or if you are a fat glutton trying to shovel food into your mouth and some of it misses, then it is very easy for a dog to just hoover up some of that food.
And the problems that cats and dogs get through being overweight are just the same sorts of problems that humans face. Diabetes, heart disease, arthritis, skin problems, cancers.
But why do fat cats have fat owners? Maybe they don't. However this fat owner, who ought to know better, has fat cats. This is primarily because they are fed ad lib and aren't allowed out of the house. So they get as many calories as they like and they don't get enough exercise. Eat less and move more. Sometimes we make a real effort to get weight off them. Sometimes we succeed. But it is hard to remember that not all interactions with our pets require some kind of food handover. Often when a pet comes and looks at you, or woofs/miaows at you, it is not saying, 'Feed me!' it is saying, 'Give me a bit of attention! That can be food, or you could throw a toy for me, or you could stroke me. I don't care what you do so long as you just give me some attention. I love that!'
Anyway, in honour of Tybalt who was ill today and I had to take him into work and, as a consequence weigh him, here are some pictures of our cats! You may have seen some of these around the site already. But look at their little faces! Aren't they cute?