Monkey Bum

Does my bum look big in this?
he question made me reminisce.
For the answer it would bring
was yes, it's big in anything.

Now months of watching what I ate
leave me glad I'm overweight.
With a new world to explore;
for yes I was obese before.

Where once I said, I know, I know,
my rear end's like an old rhino.
Today I don't seem half as dumb
for now I've got a monkey bum.