Using Inkscape I explored different ways in which I could make up a basic body shape which would be easy to identify. I think the best one to use for the obesity poster would be the circles possibly in conjunction with the swirls because they can portray a similar shape to the cells of fat present and I can effectively mutilate the size and shape of them to show different body sizes. However I do not think having the objects grouped so closely together is a good idea and may choose to just use a plain body outline and then have something inside the body such as a graph with my ideas which I experimented with below.
I think this is a better layout to consider, I used some further image research and recreated this from the following photograph which I found on shutterstock.
I have also found some other photographs I will take into consideration when picking the layout of my A2 poster and working out which shapes to use to recreate similar images.