You just generalised roughly about a billion people's diets.

> 86% of vegetarians go back to eating meat because they get sick

About half of those billion people were never not-vegetarian in the first place, i.e. Indians. They are generational vegetarians, having stuck to that diet for well over 3500 years. So either you pulled that factoid out of some unsavoury orifice, or you are badly misinformed.

> Nearly all vegetarians I've seen are nearly never obese but nearly always look weak, sick and tired

Also, source?

Americans are amongst the most 'carnivorous'[1], but there is a massive obesity, heart disease, and high cholesterol problem in the US.

[1]: https://ourworldindata.org/grapher/daily-meat-consumption-pe...