Congrats on the diet switch! I am new to this forum and pleased to see that it is so pro-veg. I have been a veggie for about 7 years, so perhaps I can answer some of your questions, along with the advice others gave. :cheerful:
1- Well, it depends on what your diet was like before. If you had a generally healthy diet that included meat, there would probably have to be ony a few small adjustments that you would have to make. On the other hand, if you ate junk all the time, then you are going to be unhealthy no matter what! lol You can substitute beans, grains, soy products, and more fruits and veggies in place of meat.
The most common lacking nutrients in a vegetarian diet are: iron, B12, and iodine. Iron is easily obtained from leafy green veggies (think spinach, kale) nuts, apricots, beans, and fortified soymilks/cereals. B12 is found in brewer's yeast and some oils, and can also be taken as a supplement. Iodine is found in sea vegetables (seaweed) and more commonly, iodized table/sea salt. Also watch calcium and Essential Fatty Acids- calcium can be found in leafy greens, fortified products and soy products, and EFAs can be obtained from walnuts and olive/veg oils. Most other nutrients vegs lack can be made up simply be eating more fresh fruits and veggies!
2- Protien is not really as hard of an issue as most people think- the average person only needs between 50-65 grams a day! Almost every food has protien in it, excluding fruits and highly processed junk food. As stated before, protien can be easily found in beans, nuts/nut butters, soy products (such as tempeh, tofu, soy milk and edamame), and whole grains. Veggies also contain protien as well, so if you are eating a well-rounded and heathy diet you will most likely be fine.
3- As long as you continue to take in enough calories to maintain your current body weight, it shouldn't matter whether you are eating meat or not.
A few tips that I found helpful when going veg:
~Experiment! Go to a local natural grocer and buy a whole bunch of veg fods that look tasty, and learn how to cook them in interesting ways! Having an interesting and varied diet will keep you healthy and will make sure you don't get bored with your veg diet. Doing this introduced me to such things as tempeh, seitan, quinoa (which is super nutritious by the way), hummus, baba ganouj, kale, avocados and many other foods I wouldn't have though to try on a meat-eating diet!
~Get a few good veg cookbooks and try a few new recipies a week!
~Try not to rely on processed foods or dairy products. Most processed foods are really high in sodium, and dairy fills you up with too many calories and not enough nutrition. Try to eat more fresh/whole foods.
~Lots of different ethnic cuisines offer lots of veg options, and are really flavorful! Try Mediterranean, Ethiopian, Thai, Indian, Chinese, or Japanese food!
~One nice thing to make in place of a meat roast is a nut loaf- a great site for recipies is
https://www.vegweb.com -I swear I have found some of the best recipies EVER here! Search their recipie section and you will find a bunch of good nut loaf recipies and a whole lot more!
Hope this helps! If you need any more info, you can feel free to PM me, or just post here! Good luck, and happy eating!
Peace
Julie