It does show that Tolkien did not think these particular hobbits (or Bilbo...remember him on the barrel?) were all that chubby. This pictures make me think that he considered them fairly graceful, much like small elves. More than once, wasn't it mentioned that Frodo had an elvish quality about him? Because of these pictures, it's easy for me to visualize. And E. Wood does a good job of completing the picture, in my mind.
Now I know that Tolkien mentions that hobbits are inclined to being fat, but I suspect that is the result of a leisurely life, and with age. An inclination, not a rule. And our hobbits were mobile, not couch potatoe hobbits!
I expect that by the time they reached Fanghorn, M and P were a couple of lean hobbits. (Quite unnatural!)