A plant based diet will seldom give the nutrients you need unless you are very mindful of it. The problems usually start with b12 that is almost only found in meat and fish. Tryptophan is another nutrient that is also abundant in meat but not so much in vegetables and fruit.

I'm not against vegetarianism. I just think that it should be done responsibly. Eat two eggs every day at least to avoid the pitfalls. And make sure to get omega 3. There are good vegetarian sources of this essential fatty acid. But meat and fish is still the major food source.