On average vegans have much healthier body weights than non-vegans. But that is not to say some don't have issues with their body weight. There are some who may just want to shed a few pounds and others that actually struggle with obesity. Obviously, just like with the general public, there are a variety of reasons for this. I think the first thing to consider is, are you consuming too much vegan junk food? With the advent of so many types of vegan convenience foods it is easy to pack on the pounds if that is what the majority of your diet consists of. Just because you eat a vegan diet doesn't mean you eat a healthy diet.
The plain and simple of it is that if you eat less calories than you burn you will lose weight. There are factors that make this harder for some people than others. There are medical conditions or medications that can inhibit weight loss...although your goals can still be achieved it may take more time than for those without such medical conditions. You should be striving for a healthy diet and life stye that will continue even after your weight loss goals have been attained.
Tips - Drink lots of pure, clean water. It should be your beverage of choice. Aim for 6 to 8 glasses a day. The juice of a lemon added to a glass of warm water in the morning can add flavor but also has the added benefit of helping to flush out toxins accumulated in the body. If you have any problems with constipation, warm lemon water usually stimulates a bowel movement within 20 minutes.
Center your meals around "whole" organic, nutrient-rich foods. Fresh fruits, vegetables and whole grains. Aim for 6 to 8 servings of vegetables a day, 2 to 4 servings of fruit, 6 to 8 servings of whole grains (foods), 2 to 3 servings of dairy substitutes (almond, soy, rice milks) and 2 to 3 servings of beans or bean products like tofu and tempeh, legumes, seitan or seeds. Nuts although very healthy are very easy to over indulge in so be mindful and use sparingly. Also oils and other fats should be used very sparingly.
Fiber is your friend! Read
this post for a list of high fiber weight loss power foods
You want to stay away from sugar, artificial sweeteners (this means diet beverages!), refined flour, caffeine, and anything that contains chemicals that you can't pronounce. Just think, If I were to make this food at home would I add this ingredient?
Pick a set time at night (example 7:00 or 8:00 pm) and do not eat after that time.
Move - Find an exercise that you like and do it...often. At least 4 times a week. It can be as simple as walking. I personally love yoga. A good Vinyasa Flow practice can be more aerobic than an aerobics class, in other words a great cardio work out. You will burn calories and stretch and tone all at the same time. What ever exercise you choose, just set aside a time period and do it.
Meditation - Meditation allows you to just sit and be quiet. It is good for stress and enables you to recharge. Think of it as an investment in your health and spirit. A daily practice of at least 20 minutes is ideal but aim for what ever you feel is right for you right now.
List of Healthy Weight loss food choices - 
Organic fruits and vegetables
Beans and soy products, legumes, seeds and nuts
Organic canola, olive, sesame, and coconut oil
Brown rice, barley, quinoa, millet, oatmeal, whole-grain cereals and bread, whole grain pastas, and whole grain tortillas
Water, green tea (decaffeinated), kukicha tea, and unsweetened herbal teas
A typical meal plan might look like this:
Breakfast: Lemon water, oatmeal made with almond milk and sprinkled with blueberries
Lunch: Salad with lots of raw vegetables and garbanzo beans (squeeze the juice of a fresh lemon on top or make your own dressing), apple
Snack : eat a small portion of any healthy weight loss food (list above) - only if needed.
Dinner: Stir Fried veggies with tofu chunks serve over brown rice, cup of kukicha tea
