At the time I wrote that piece, I did not have any medical or scientific references to back it up. I had spent a bit of time trying to find something to support the idea, but it was difficult to find anything. There is not too much research out there on being overweight and running barefoot. What I wrote was just my opinion based on my own experience and kind of using my own logic based on my limited knowledge so far about barefoot running.
However, today, I have found a reference that might indicate that I'm thinking in the right direction when I suspect that running barefoot is better for overweight runners.
On Dr. Michael Nirenberg's blog (America's podiatrist), in his post "Barefoot Running With Eyes Wide Open," he references a 2006 study which "established that individuals with arthritic knees could reduce the impact loads on their hips and knees by nearly 12% by doing nothing else but simply taking off their shoes."
The Livestrong post quoted above basically reflects the standard advice out there regarding people who are overweight and running: Overweight people need sturdy support with extra motion-controlled and need to pay even extra more for good running shoes. So, if barefoot runners already face hostility for challenging the conventional wisdom about needing support from shoes while running, then my hunch that barefoot running is better for the overweight is going extremely overboard and turning the conventional wisdom completely upside down.