Hi Mara,
First of all, great choice on going vegan! A plant based diet, when done the right way, is definitely the healthiest way to go. I say "when done the right way" because unfortunately there are a lot of "malnourished" looking vegans out there that aren't getting proper nutrition in their diet.
First of all, you're going to be fully nourished when it comes to key micro nutrients from eating an abundance of greens, colored veggies, and fruits. The best thing about vegetables is that they are micro nutrient rich but very low in calories.
One thing you do need to look out for is tailoring your macro-nutrients (fats, carbs, protein etc) and making sure you're not just taking in all carbs. A lot of vegans live on whole grains like quinoa and fruits, which are great, but you definitely need protein (quinoa doesn't have as much protein as people think). You want to make sure you're getting whole food plant protein. Some of my personal favorites are lentils, black beans, split peas, and I also like some of the fake meats out there by Gardein and Beyond Meat. Make sure to look at the nutrition facts and ingredients labels on the fake meats though. There are a lot of fake meat products that use soy protein and other inferior sources as well as have bad macro nutrient ratios (protein:carbs:fat ratio). A lot of them have lot of fat in comparison to how much protein you're getting. I prefer BeyondMeat products because their protein source is usually pea protein and you get a lot of protein and not much fat (except their BeyondBurger which has a lot of fat).
Are you staying physically active and participating in resistance training? Proper nutrition and protein intake coupled with resistance training will help you retain and build healthy lean mass.
For convenience and the ability to tailor your macro nutrient ratios and proportions (from a fitness stand point), I recommend a vegan protein powder. The reason I do this is because sometimes I just want a pure protein meal without carbs or fats. Most of my favorite whole food vegan protein sources (lentils, split peas, black beans etc.) aren't pure protein. They still have a 1:2 sometimes 1:3 Protein To Carbs ratio. You do NOT need a protein shake. However, they definitely help especially if you're physically active.
I hope this helps!
