Vegans eat more than salad and being vegan can be very healthy. Obviously, there are unhealthy vegans (you can get vegan donuts, cupcakes, icecream, etc..), just as there are unhealthy meat eaters.
If you are interested in losing weight, you may want to check out the McDougall Maximum Weight Loss plan. It's vegan, but whole foods (no pasta, soy milk, tofu etc..) and its worked in the past for me (I should be on it now as I have pounds to shift!).