Food and Health Personal Health

Plant-Based Weight Gain Tips: How to Gain Weight the Healthy Way

11 min read

Conversations around weight usually revolve around losing extra pounds, but that isn’t the story for everyone. Many people actually struggle with the opposite — feeling underweight and wanting to gain pounds to achieve an optimal weight. Here’s how to gain weight in a healthy way, on a plant-based diet.

For many people, losing weight is one goal in the larger journey to better health, as it has been well-established that excess weight can contribute to chronic health conditions. Starting a plant-based diet and eliminating fast food, processed food, and animal products almost inevitably allows for the pounds to come off. This is in part because of the associated improved metabolism, higher water intake, higher fiber intake, and reduced fat and overall calorie intake that comes with eating plants. Many studies have found that the average vegetarian or average vegan tends to weigh less and to be less likely to be overweight or obese.

But for some, weight loss isn’t the goal. And losing weight might actually be unnecessary and even detrimental to their health. If you’re struggling to gain weight to reach a healthy weight, or you’ve lost too much and are now underweight, how do you gain weight on a plant-based diet without overeating or eating unhealthy, processed foods? And how do you gain weight in the places you want it — like in your muscles — and not around the middle?

Health Risks of Being Underweight

Female runner holding knee

Why does being underweight matter? For some people, it comes down to more than wanting to look a certain way. Being below your ideal weight can actually be detrimental to your health.

Being underweight can result in fatigue, and can make a person feel weak and low in energy.

For women specifically, not having enough bodyweight — especially body fat — can result in hormone irregularities and disruptions in the menstrual cycle, which can be detrimental to bone health. Being underweight can be especially dangerous for pregnant women and can increase the risk of premature births.

The risk for malnutrition increases for people who are underweight, due to not getting enough calories or absorbing enough nutrients. Nutritional deficiencies are also more likely, including anemias. Malnutrition can lead to hair thinning or loss, osteoporosis and weakened bones, dry skin, teeth issues, reduced heart function, impaired immunity and wound healing, gastrointestinal changes, and depression.

Why Do Some People Struggle to Gain Weight?

Sad woman separated from group of people

Lack Of Food

Globally, the most common cause of being underweight is poverty. Today, worldwide, more than 821 million people are facing food insecurity. In June of 2020, a Kaiser poll found that 25% of all Americans were skipping meals or depending on food donations in order to eat at all.

Humanity produces enough food to feed over 10 billion people. So never believe the myth that hunger and malnutrition are necessary. They are not. In a world of sufficiency, it is a source of enormous frustration and grief that we haven’t yet been able to make hunger history.

Until we get there, the continued existence of hunger and malnutrition are real problems that deserve attention from all of us.

(For tips on how to eat healthfully on a budget, click here. To support America’s largest hunger-relief organization, Feeding America, click here.)

After a shortage of food, the next most common causes of being below ideal weight are likely to be medical, genetic, and/or lifestyle-related.

Medical Challenges

There are a few potential medical challenges that may be the culprit for being underweight. Hyperthyroidism, a condition in which the thyroid is overactive and boosts your resting energy expenditure, can lead to a high metabolism that burns more calories than you take in. Cancer can significantly reduce appetite, especially if you’re undergoing chemotherapy or taking medications that cause nausea. Digestive problems, like Crohn’s disease, celiac disease, or ulcerative colitis can also impair the absorption of nutrients and reduce appetite, leading to unwanted weight loss.

Some autoimmune conditions can reduce appetite, cause intestinal malabsorption, and make weight gain challenging due to digestive issues like bouts of vomiting or diarrhea. In type 1 diabetes, the kidneys are often working to rid the body of excess sugar through urine, which can lead to water-related weight loss and loss of calories from unused glucose. Plus, type 1 diabetes may cause the body to burn fat and muscle for energy at times when not enough glucose is available, leading to weight loss. And parasites, like having a tapeworm infection, can lead to weight loss largely due to having a foreign invader in your body consuming some of your calories.

Restrictive eating disorders such as anorexia, as well as certain metabolism-boosting or appetite-suppressing drugs such as amphetamines or even tobacco, can also result in not consuming enough food to sustain your weight.

Metabolism & Genetics

Some people may have a genetic predisposition to being underweight. Have you ever noticed that some people seem to be able to eat whatever they want and never gain a single pound? While people joke that this is a desirable trait, it can be extremely frustrating for someone who wants to gain weight. Basal metabolic rate — or how quickly your body burns calories at rest — is partly determined by your genes. You may be more likely to have a “fast metabolism” if you have family members who do too.


And lastly, some people simply burn more calories than they consume. If you’re highly active, under significant stress, or if you just plain don’t eat enough, then you may need to eat more calorie-dense foods. But does that mean you have to add a steady dose of heart disease-fueling french fries and burgers?  Not at all! As you’ll soon see, there are plenty of ways to add healthy calories to your diet.

How is Being Underweight Measured?

The basic definition of being underweight is weighing less than is required for optimal health.

Whether your weight is considered to fall within or outside of a healthy weight range is typically determined by your body mass index, also called your BMI. Your BMI is your height to weight ratio, calculated by your weight in kilograms divided by the square of your height in meters. While a healthy BMI is typically considered anywhere between 18.5 and 24.9, being underweight is defined by having a BMI of less than 18.5.

Even though the BMI is a widely used tool, it’s deeply flawed, because it makes no distinction between a pound of muscle, a pound of bone, or a pound of fat. The BMI calculation doesn’t take into account a person’s muscle or bone mass and may overestimate body fat in athletes and others with muscular builds. It may also underestimate body fat in the elderly, or others who have lost significant muscle or bone mass for some reason. Having a high or low BMI doesn’t necessarily mean a person’s weight is in an unhealthy range. But for many people, it’s a helpful gross metric.

There are other determining factors of your health, such as your waist circumference, too. There is no set weight circumference size for underweight people, but for overweight people, it’s over 41 inches for men and over 36 inches for women. When combined with your personal health history, a combination of your BMI and waist circumference can be used to assess your risk for certain health conditions.

Exercise Tips to Help You Gain Weight

Senior woman doing weight-bearing exercise on yoga mat

The healthiest type of weight to gain is usually muscle. That’s why, even though it may sound counterintuitive, you need to move your body in order to put on an optimally healthy weight. But some exercises help you gain a healthy weight more effectively than others.

Doing cardio exercises, like running, swimming, or taking an aerobics fitness class, isn’t likely to help. While these kinds of activities offer many benefits to your overall health, and can help with muscle tone, cardio exercise also makes you burn a lot of calories, which can lead to unwanted weight loss for some people. If your goal is weight gain, you can still enjoy some cardio exercise, but don’t make it the focus of your activity.

Instead of constant cardio, weight-bearing exercises, and other forms of strength training, are the best ways to gain weight and muscle mass. Some of the most effective exercises to gain weight include pushups, pull-ups (also called chin-ups), squats (using dumbbells for extra resistance), planks, and doing weight-lifting exercises like bench presses, free weights, and overhead presses with a weighted bar. Resistance training, or strength training using bodyweight instead of free weights, is another great option for people wanting to gain muscle mass.

Sleep Well for Weight Gain

Man in bed sleeping on pillow

Did you know that getting enough nightly zzz’s isn’t just good for your mental health and energy levels, it’s also a critical component of achieving weight goals? Research shows that adequate, quality sleep will help you build muscle and, in turn, gain weight — or at least maintain a healthy weight.


A 2017 study published in the Journal of Musculoskeletal Neuronal Interactions evaluated handgrip strength and self-reported sleep quality and duration among 10,125 university students aged 16-30 years. The authors concluded that good quality sleep at night was associated with greater muscle strength. Oppositely, not sleeping enough may be a risk factor for reduced muscle strength.

A 2018 study published in the Journal of Science and Medicine in Sport, examining seventeen studies, aimed to evaluate the impacts of sleep deprivation on resistance exercise performance. The authors found that not getting enough sleep inhibits muscle strength in exercise.

Diet Tips to Gain Weight

Person pouring mixed nuts out of jar into hand Ricco

The formula for gaining and achieving a healthy weight includes not only exercise and quality sleep, but also what you eat. The good news is that almost everyone can gain weight, if they want to, on a whole foods, plant-based diet.

Here are a few tips to help you make the best food choices for healthy plant-based weight gain:

Quality Over Volume

While you may need to eat more food overall, keep your focus on choosing nutrient-dense and calorically-dense foods. Pay attention to foods that will help you get enough macronutrients — carbohydrates, fat, and protein — and will also help you meet your needs for vitamins, minerals, antioxidants, and phytochemicals. This may mean focusing on foods that don’t fill you up with air and water — and aiming for more calorically dense whole foods (more on that later).

Eat More Calories Than You Burn

You may have heard the phrase “calories in, calories out,” which essentially means that if these two things are equal, your weight will remain steady. While the reality is a good deal more complex, since metabolism and other factors come into play too, this is still a useful reference point. If you’re trying to gain weight, you’ll want to eat more calories than your body burns on an average day.

To get an idea of how many calories your body burns, you can try using a calorie calculator like this one. Here, you can plug in basic information like age, gender, height, weight, and typical activity level to get an idea of how many calories you need for various goals. To determine how many calories you need to gain weight, you’ll need to eat more than the amount calculated to maintain your current weight. To meet this goal, you may need to increase portion sizes, and to consider eating more often, including potentially adding snacks and smoothies.

Keep a Food Diary

This doesn’t mean pouring out your innermost food secrets into a journal (although you certainly could!). It means writing down what you’re eating to help understand your eating habits and adjust accordingly. Keeping a food diary — which can be done using pen and paper or an app like MyFitnessPal — can help you see if you’re eating enough to promote weight gain. Also, it can help you figure out which foods you should eat more of, based on how many calories they contribute to your day.

Healthy Plant-Based Foods to Gain Weight

Healthy plant based weight gain foods

In order to gain healthy weight, you’re going to need to incorporate plenty of nutritious, high-calorie foods into your regular diet.

Fruits, vegetables, and other low- to moderate-calorie whole plant foods should remain a major part of your diet as they offer tremendous health benefits. However, you’ll need to balance in foods that contribute more calories in sufficient serving sizes. This will help make sure you get the calories you need for plant-based weight gain without feeling stuffed or uncomfortably full from having to eat excessive volume.

Some of these more calorically-dense, whole plant foods include:

Note that if cost is a big consideration in your meal plan, then you might want to focus on the cost per whole foods calorie more than the cost per pound. For example, peanuts, legumes, soy foods, and whole grains shine in this regard, offering a substantial amount of relatively inexpensive calories and healthy nutrients per pound.

Unhealthy Foods to Avoid (Even if They Help With Weight Gain)

Pizza, burger, fries, and cupcakes on table: Unhealthy foods for weight gain

While calorically-dense, high-fat foods are more likely to make you gain weight fast, many of such foods found in the standard American diet are high in unhealthy trans fats, saturated fats, sodium, added sugars, and chemicals that bring numerous negative health effects.

Some of the foods that may contribute to unhealthy weight gain include animal products like red meat, eggs, commercial baked goods and sweets, fast food, bottled oils, as well as chips and similar packaged and processed snack foods.

The foods listed above make up a significant portion of what people eat on the modern industrialized diet. Eating nutrient-poor, empty-calorie foods may promote weight gain, but they also encourage the development of conditions like heart disease, type 2 diabetes, and even certain cancers.

Fortunately, there are many healthy ways to gain weight. And to make it even easier (and more delicious!), here are some recipes to try.

Weight Gain Recipes

Smoothies, sprinkles, and sweet endings to a meal all make for delicious and nutritious additions to your daily diet.

1. Peanut Butter Smoothie for Weight Gain

Peanut butter smoothie for weight gain

One of the simplest weight gain recipes you can play with is the smoothie. What you put in it matters, of course. Start with this irresistible blend — greens included! And then enjoy a variety all week long by changing up the nut or seed butter, fruit, and vegetables!

2. Vegan Walnut Parmezan

Vegan walnut parmezan in bowl

If you’re having a difficult time gaining weight and don’t want to feel overstuffed, then try “sprinkling.” Use higher-calorie plant-based foods as the final touch on meals that you already enjoy, like one to two tablespoons of this “parmezan” on soups, salads, veggies, pasta, and grain bowls.

3. Avocado Key Lime Pie

Avocado key lime pie

A nutrient-dense dessert that can help you gain healthy weight? Coming right up! Made with avocados, pecans, and coconut, this dessert definitely has plant-powered calories. However, it also comes with its share of nutrients. Chock-full of healthy fats, vitamin C, vitamin E, vitamin K, and B vitamins, your body will thank you for this nourishing treat.

Weight Gain in Summary

Female runner showing her muscles

In a world that often seems obsessed with weight loss, many underweight people feel left out in the cold. But being underweight can be detrimental to your health as well, increasing your risk for malnutrition and a variety of health conditions. If you want to gain healthy weight with a healthy diet and lifestyle, you can do so with whole, plant-based foods. For many people, it all starts with eating plenty of nutrient-dense and calorie-rich foods, doing strength training exercises, and sleeping well.

Tell us in the comments:

  • Have you or anyone you know used a plant-based diet to successfully gain weight or muscle?
  • What are some of your favorite ways to incorporate nutrient-dense and calorie-rich plant foods into your diet?
  • What are some of your favorite strength training or resistance exercises that could be used to support healthy weight gain?

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