You don't have to be vegan to lose weight. You don't have to not be vegan to gain weight. It's not just about what you eat, it's also how much you eat. A vegan can become overweight and stay a vegan, and vice versa. I'm of average weight for my height and age, and I eat generally unhealthy foods. That said, that could be a combined working of the frequency as well as a high metabolism. Furthermore, I'd like to point out that (based on a test administeted by professionals), I am a very intelligent person. I am not a vegan. I have never been a vegan. Could I be an outlier? Absolutely. That said, I think my point still stands.