If there was a study, I would volunteer. I'm an omnivore now for 20 years, after being vegetarian for about the same amount of time, never vegan. I live a reasonably healthy lifestyle but office job and do like to drink about thrice a week, only one drink (so moderate, I think) . I'm sure there are lifestyle matched vegetarians and vegans.

Personally I'm healthier but heavier (was underweight, now middle of healthy BMI which feels fat to me but I do literally feel good) with some meat in the diet but don't eat it every day. Cholesterol was high when I was vegetarian, still is. Only thing that drops that is regular fasting, which unfortunately was a reliable migraine trigger for me.