A very astute observation by TKGS. A Catholic should never call themselves a vegan.
My neighbors wife (non-Catholic) is a vegan, its a recent change in the last 2 years, she was slim and fit before, now she's put on weight, she looks bloated, a big change. I think it is from eating too much soybean based protein. The two vegans I know, look unhealthy.
I do not believe any major deviation from a traditional diet is going to be good for you. If you eat fresh vegetables, fruits, whole breads, and meats, butter, eggs......, avoid processed foods and overeating, and do exercise and physical activity, you will not need any of these "new and improved marketing ploys" like veganism and such. One can try one of these gimmicks, like the paleo diet to get back to healty weight more quickly, however, one should always return to a traditional diet. People who are overweight and unhealthy are so because they ate junk and didn't exercise. It is that simple.