Several years ago I read a statement to the effect that you don't accumulate fat cells as an adult, you just enlarge the ones you have. It was a statement in commentary on a website, with no supporting evidence.
It was one of those comments in passing, that rolls around in the brain as having superficial merit, and so you wait, until the evidence catches up with it, or doesn't.
In this case, the evidence did.
From the magazine "Nature":
The factors determining fat mass in adult humans are not fully understood, but increased lipid storage in already developed fat cells (adipocytes) is thought to be most important4, 5. Here we show that adipocyte number is a major determinant for the fat mass in adults. However, the number of fat cells stays constant in adulthood in lean and obese individuals, even after marked weight loss, indicating that the number of adipocytes is set during childhood and adolescence.
People find roly poly puppies irresistible. Cute little round fur balls are often proclaimed 'what a healthy looking pup'!
(Same goes for children too.)
But the life time of problems (Hip Dysplasia, anyone?) that obesity brings with it, are anything but healthy.