While the findings in this article are interesting, I would take it with a grain of salt. It's always hard to say why a limited number of people might do better on one diet than another, but generally, I'd be careful when interpreting results of very restrictive diets. Vegan diet doesn't allow any meat, egg or dairy products, and personally, that would leave me without anything that I truly like to eat, which I am sure would lead to weight loss. Another thing it would lead to is cheating and failure to comply with the diet for very long.