How do I determine if my pleco is a healthy weight?

[redmare]

I've got a beautiful juvenile bristlenose (who I've named Princess Peach) and I was wondering what to look for to make sure she's getting enough food. If anyone has photos of healthy, overweight, and underweight plecos that would be super helpful! Or just any descriptions that can help me make sure she's eating enough but not too much.
I've put a photo of her below. I've only had her about 2 weeks now.

 

[Flyfisha]

Long term under feeding produces a big head with a narrow short body.

In that photo I see a nice shape, particularly half way from nose to tail .
I don’t recall ever seeing an overweight BN pleco?