As a slightly controversial conclusion (perhaps) I’d say that we have altered what we consider to be the norm with respect to size. We accept larger as normal. Portion sizes at McDonald’s are much larger than they were 70 years ago. Cars are much larger than they used to be. We are larger than we used to be – and that mostly means wider but also taller. Consequently our cats are wider too. Or to put it another way cat obesity is a problem in 2015 as is diabetes (a consequence of obesity and certain commercial cat foods, it is believed). So the Big Mac is linked to the domestic cat.