Why is obesity so prevalent in the human species but doesn't seem to be in other animal species?

Obesity we all know is a big problem now, and I was wondering about humans compared to other animal species. You don’t tend to see overweight giraffes or birds etc. They have just as easy access to food as we do, especially those that eat mostly vegetation. So what is it in the human species that we can’t just eat to be satisfied like other animals, instead we eat and become overweight?