I agree that woodsman would not have been so out of shape and carrying extra pounds. Until middle age, farmers would not have been carrying extra pounds.
However, townspeople and the rich had their share of folks carrying extra pounds. Cooks especially were often not trusted to cook well if they were skinny. Some tradesmen would have been skinny, but some tradesmen would have packed extra pounds on when their trade did not require as much physical exertion. Tailors, cordwainers and the like would have been more likely to have extra pounds.
What we often do not think about is the quantity of booze they drank in those days. That can easily pack on pounds they didn't get from food.
I'm too old and am carrying too many pounds to truly be representative of even a "professional private" in the Major's Coy, 42nd Royal Highland Regiment - though I'm still in better shape than some folks 20 or even 30 years my junior. Most enlisted soldiers of the British Army would have been skinny, though some of the Officers were pudgy to downright fat.
Packing extra pounds was often looked upon as being prosperous then.
Many of these gentlemen are packing some extra pounds.
http://images.quickblogcast.com/4/6/0/6/4/155407-146064/declaration_of_independence_signers.jpg