Definitely not! You will not lose muscles if you go vegan.
There are millions of people who choose vegetables for their diet and still have well-cut muscles and strength like meat-eaters. It’s damn true that animals flesh is a heavy ingredient to add muscle and increase metabolism in our body. However, there are numerous plants which provide protein and other healthy nutrients for building muscles.
Apart from this, plant foods contain many antioxidants which aid in reducing the intensive load, exercise imparts on the body. Hence, there are many reasons which prove a vegan diet is an effective way to maintain a healthy and muscle in real life.
Jon Venus,a bodybuilder,a trainer has proved that vegan diets can also help to build muscles. He went for vegan dies for three months and despite eating only vegetables, he gained a superb body.