Why do fruitarians look old and unhealthy?

[dime]

Well the protein supplements are irrelevant if protein should be kept at 10% of calories (40-50g protein a day, assuming 2000kcal a day).
It'd be hard to build muscles with that little protein indeed, it may be just enough for maintenance (if the protein is 'complete'). Without animal food it would be hard to get complete protein from only 40-50g.