Here is a sample of how to sketch out overweight characters by drawing different shapes in the beginning sketch lines and then refining them. You can watch a video of this on my Youtube channel if you like.

Jerome Okutho's insight:
A unique reference guide for anyone interested in learning about the anatomical differences between overweight and muscular characters.
Una guida di riferimento unica per chiunque sia interessato a conoscere le differenze anatomiche tra personaggi in sovrappeso e muscolosi.