How to Gain Weight on Vegetarian Diet

Vegetarians sustain themselves entirely on spinach and carrots, so they're just fated to be thin and underweight, aren't they? Not necessarily — in fact, with some nutritional know-how, it's easy to put together a vegetarian weight-gain meal plan that is both nourishing and tasty.

Before discussing how to use a vegetarian diet for weight gain, it's important to understand how weight gain works. Being underweight can present health problems just as being overweight can, according to the American Academy of Family Physicians. Being underweight could mean that your body isn't getting the nutrients you need, resulting in fragile bones, a weakened immune system, anemia, fertility issues and hair loss.

As with weight loss, weight gain is about calories in and calories out; however, while weight loss requires a calorie deficit (that is, you consume fewer calories than you burn), weight gain requires a calorie surplus.

Because of the health problems associated with being underweight, getting nutritious food is just as important as getting a lot of it. The American Council on Exercise (ACE) emphasizes that if you're going to gain weight in a healthy way, you must be opting for highly nutritious food. The Academy of Nutrition and Dietetics agrees. Extra calories won't do you any good if you're not getting the nutrients you need for strengthening your bones or repairing tissue.

ACE explains that muscle growth results from weight or resistance being applied to the muscle tissue you currently have. While your muscles are recovering from this stimulation, extra calories and a good balance of nutrients will help your muscles grow. You should aim to get approximately 300 to 500 calories above your caloric needs, and those calories should come from a balance of carbohydrates, protein and fat.

Read more: The 21 Best Muscle-Building Foods For Vegetarians

Here's the part that's important for vegetarians to note: Eating a ton of protein won't necessarily lead to muscle growth, so you aren't at a disadvantage just because you don't eat meat. Instead, you should aim for both carbohydrates and protein before, during and after your strength training exercise. A recovery meal should have a carbohydrates-to-protein ratio of 3-to-1 or 4-to-1.

A vegetarian diet for weight gain won't always be healthy. If you ignore fitness and nutrition advice, vegetarian diets can easily cause unhealthy weight gain. Without the resistance training to build muscle or the proper nutrients your body needs to function, you could end up gaining excess fat instead.

As the National Institute of Diabetes and Digestive and Kidney Diseases explains, a healthy vegetarian eating plan has the potential to lower a person's risk of obesity, high blood pressure and heart disease, but there are still plenty of meat-free foods that are high in sugar, fat and calories.

Vegetarians should focus on filling their plate with foods that are good for them, including vegetables, fruits and whole grains. If they are vegan, they will have to stick entirely to plant-based products for their protein — USDA ChooseMyPlate recommends beans, nuts, seeds and soy products — but if they're lacto-ovo vegetarian, they can turn to milk products and eggs for protein as well.

Read more: 12 Tips to Getting a Vegetarian Diet Right

Now that you understand how to eat for weight gain and what vegetarians can do to be healthier, it's time to look at ways you can make that nutritional wisdom work to your advantage. Here are a few ideas to start incorporating into your vegetarian weight-gain meal plan:

Find more opportunities to eat throughout the day. Mayo Clinic suggests going for five or six smaller meals rather than three large meals. This will give you more opportunities to consume calories and nutrients. This advice is supported by the Academy of Nutrition and Dietetics.

Consider foods that have a lot of calories for very little volume, and snack throughout the day on options that are calorically dense with a combination of protein and complex carbohydrates.

The American Academy of Family Physicians recommends snacks like trail mix, protein bars, crackers with hummus or crackers with peanut butter. Per the USDA, peanut butter has 188 calories per 2 tablespoons. While hummus has only 50 per 2 tablespoons, it does offer a nice balance of fat, complex carbohydrates and protein.

Top the food you're already eating with calorically dense extras. A salad or a bowl of cereal will make an even heartier meal if you top it with something like sunflower seeds, which the USDA lists as having 165 calories per 1-ounce serving.

Other ideas from the Academy of Nutrition and Dietetics include making your morning oatmeal with milk or cream instead of water (if you're lacto-vegetarian) or making your salad with olive oil, whole olives and avocado.

If you're looking for creative salad ideas, check out LIVESTRONG.com's Pistachio Crunch Salad, which includes crackers, garbanzo beans and pistachios for a few more calories than just a bowl of lettuce and chopped veggies.

Consider how you can stimulate your appetite and avoid suppressing it. Mayo Clinic recommends avoiding too much fluid right before a meal — you don't want to fill up on calorie-free water and find that you don't have any room left for dinner.

If you don't have much of an appetite, however, sipping on a protein smoothie could be a good way for you to take in plenty of calories between meals. Lacto-vegetarians will love LIVESTRONG.com's Paradise Smoothie, which includes Greek yogurt (the recipe calls for a low-fat version, but you can use full-fat yogurt for more calories), avocado and grapeseed oil. Are you vegan? Why not go for our Bunny Food Smoothie, which is made with tofu.

Don't forget to engage in plenty of physical activity, which will not only help build muscle but also give you an appetite at mealtime.

As you go about following a vegetarian weight gain meal plan, be aware that many plant-based foods will fill you up without too many calories. This is one reason among many that the Centers for Disease Control and Prevention recommends eating more fruits and vegetables for people who are trying to lose weight, and it's why it can be especially important for any vegetarians who are underweight to focus on including calorically dense, healthy options.

With proper planning, a vegetarian diet for weight gain should not be too hard to follow.