How Can I Gain Weight In 7 Healthy Ways?

The healthy weight conversation has been centered around obesity, but should also include underweight individuals.

It may seem like being thin in this way is to be desired, however the reality is that being underweight comes with the risk of many health problems. 

Some people struggle to gain weight – me included. As a certified personal trainer, I’m naturally thin, so I became determined to add muscle to my frame when I started weight training 9 years ago.

Since then, I’ve learned a lot about my specific dietary needs to maintain my physique.

I was born with this body type, but some people may be underweight due to health conditions or poor nutrition. If you fall into these categories, keep reading to find out ways to gain weight. 

Fact Checked and Reviewed By

Brooke Pieke
MS Nutrition

Here’s what’s coming up. 

7 Ways to Gain Weight
Defining Underweight
Causes Of Being Underweight
Health Risks
Bottom Line

7 Ways to Gain Weight

gain weight

The simplest way to gain weight is to eat more calories in the day.

According to the USDA’s 2020 “Dietary Guidelines of Americans,” adult females need 1,600-2,400 calories a day, while adult males need 2,000-3,000 calories a day.

Below you’ll find 7 ways you can gain weight, and if you need tips on bulking, check out my Ultimate Guide To Bulking.

Eat More Frequently

Instead of 3 meals a day, you can have multiple mini-meals.

Keep healthy snacks around the house to munch on, or have an occasional treat. Top-off your food and drink with extras like nuts, shredded cheese, whole milk, or cream.

“It doesn’t really matter if you have 3 meals a day or 5 to 6 meals a day, as long as you are getting the calories you need.

Pros of small, frequent meals are that they are good for people that have smaller appetites. But they keep your glucose and energy levels stable throughout the day.”

Brooke Pieke, MS Nutrition

Don’t Drink Water
Before The Meal

This study shows that drinking water 30 minutes before a meal may help to increase feelings of being full. Drink less during the meal too, so you fill up with more food than liquid. 

  • The speed at which you drink matters too (sipping vs. chugging).
  • Drinking water quickly, or chugging it, can fill up your stomach rapidly.
  • This leaves less room for food and less opportunity to gain weight.

Choose Nutrient Rich Foods

Protein, carbohydrates, and healthy fats are essential macronutrients to gain weight.


Animal based proteins include: beef, bison, lamb, pork, chicken, fish, eggs, milk, yogurt, greek yogurt, and cheese.

Non-animal based proteins include: beans of all kinds, pumpkin seeds, hemp seeds, sunflower seeds, lentils, nuts, nut butters, quinoa, and amaranth.


Carbohydrates are important for fueling your body and include: breads, pastas, cereals, grains, tortillas, starchy vegetables like potatoes, sweet potatoes, corn, and squash. 


Unsaturated fats are best. These can be found in olive oil, avocado oil, nuts and seeds, and pure ghee and grass fed butter.

While increasing your protein, carbohydrate, and healthy fats intake, remember to eat foods that have the nutrients to keep your body healthy.

The method of dirty bulking, where you eat anything in sight, does make you gain weight.

But it comes at the cost of consuming sugars, fats, and processed foods that do the body more harm than good. 

“Quality first, quantity second. A balanced plate is so important to keep us healthy. It’s important to read the labels when shopping too. Avoid the light calorie and aim for full fat.

On the flip side of that, heavy protein and fat products can be super processed. The more ‘natural’ the better.

Oils or liquids needed in the cooking process can be swapped for more calorie/nutrient dense options (e.g. avocado oil for veggie oil, milk for water).

I also saw adding powdered milk in addition as a way to sneak in more calories to gain weight when making oatmeal for example.”

Brooke Pieke, MS Nutrition

Drink Liquid Calories Between Meals

Smoothies and shakes are a good option to get in extra calories to gain weight. You can add fruits, milk, or protein powder.

Keep high sugar drinks like soda at a minimum. Why?
Although you can gain weight, soda and other sugary beverages are high in calories but offer little to no nutritional value.

Use Bigger Plates

This study shows that shows that having larger amounts of food in front of you gives visual cues to your brain and stomach to try and eat all of it. A simple solution like this is an easy way to gain weight over time.

Weight Training

If you have trouble eating more frequently, training with weights is a perfect way to increase your appetite and gain weight.

  • Weight training uses resistance like weights to build muscle mass. This in turn increases your weight because muscle is denser than fat.
  • A common place people train weights is of course the gym.
    There are different kinds of gyms to suit the lifting style you prefer.

When it comes to the gym, you may wonder how often to go. I explore that question in depth and give you the best answers in my post here.

It may also be a foreign idea to even go to the gym. If that the case for you then read more about why people go to the gym.


There are several options available to gain weight.

  • Proteins are building blocks for muscle, so a powder provides an efficient way to get extra protein for the day.
  • Creatine is an amino acid found in the body, and it’s highly researched and effective for weight gain.
  • You can add fish oil to your caloric surplus for healthy omega-3 fatty acids.
  • Weight gainers are powders that are high in calories. It’s easier to drink the calories you’d normally eat. 

“In my classes, we were heavily taught to avoid supplements IF you can get what you need from foods (minerals, vitamins, and macronutrients).

I would advise upping foods that are protein heavy, healthy fat, and have dense calorie to nutrient ratio prior to reaching for supplements.

However, I know that can be easier said than done so supplements have their role. Just be mindful of the amount of sweeteners and sugars that are in some of them.”

Brooke Pieke, MS Nutrition

Defining Underweight

gain weight

Being underweight is defined by the Body Mass Index (BMI). While it has many problems, BMI is still used in the medical community to measure body fat based on weight and height.

Doctors use BMI because it’s a fast, inexpensive way to gauge a person’s health. But some problems of BMI include not accounting for muscle mass, body composition, or age. 

“Nutritionists and dietitians don’t really use BMI. When they do, there is a small percentage for adjustment.” 

Brooke Pieke, MS Nutrition

BMI ranges from 18.5 to 40.0 

<18.5 = Underweight

18.5-24.9 = Normal Weight

25.0-29.9 = Overweight

30.0-34.9 = Obese Class I

35.0-39.9 = Obese Class II

> 40.0 = Obese Class II

A healthy weight is defined as a BMI 18.5 to 24.9. Anything below 18.5 is considered underweight.

Being underweight doesn’t always mean that you’re unhealthy. Your build depends strongly on your genetics. If you have a thinner frame, chances are you were born with a fast metabolism.

Metabolism is the rate that your body converts food into fuel. It can be harder for a genetically skinny person to gain weight, but it’s not impossible. 

People who are underweight and unhealthy can experience symptoms like fatigue, and low blood pressure, sugar levels, and heart rate.

If you feel these symptoms often and have not determined why, here are some causes of being underweight that will help you figure it out. 

Causes Of Being Underweight

While there are several reasons that an individual may be underweight, here are 4 causes that are common.

Chronic Stress

Stress can come from your school, job, family, or socioeconomic status. It causes physical and emotional changes to your body that require attention.

  • Dealing with the problems can take your mind off of eating and lessen your appetite.
  • You may even feel nauseous and tense at the thought of food during these tough times.

This study found that 40% of participants decreased the amount of food they ate when stressed. A solution can be to find mild foods that you can stand to eat and stick with those until you can have a full meal.

Eating Disorders

Family history, low self esteem, distress, or negative feelings about your body image can make you obsess about your weight and food.

Find a safe way to talk about these issues with a therapist or counselor. They can give you good and valuable information to help you recover and gain weight.


You can experience weight loss due to a number of diseases. Common illnesses like the cold or flu can cause a loss of appetite.

  • Having an under active or overactive thyroid can prevent hunger because this gland releases hormones that regulate your metabolism.
  • Digestive diseases like celiac or irritable bowel syndrome have negative effects on your guts and can make you not want to eat.
  • Serious diseases like cancer can also cause a syndrome known as cachexia, where there is a loss of muscle and fat.

Talk to a medical professional if you experience sudden weight loss and are unsure why. 


Some prescribed medication can cause loss of appetite and weight loss, among other symptoms. Treatments for cancer like chemotherapy, radiation, or immunotherapy  also cause weight loss. 

Health Risks

Your body needs sufficient calories, vitamins, and minerals to function properly. Being underweight means that you may not eat enough in your diet to get those appropriate nutrients or gain weight.

Here are some health risks that can come with being underweight. 


This is a condition where the body has less red blood cells than normal. Symptoms of anemia include weakness, fatigue, and headaches.

While there are many causes of anemia, diet centered causes come from the lack of certain nutrients. RDA stands for recommended daily allowance.

  • Vitamin B2 (Riboflavin)
    • Animal protein, yogurt, fortified cereals, cottage cheese, spinach, tomatoes, mushrooms 
    • RDA: Women 1.1 mg/day. Men 1.3 mg/day 
  • Vitamin E
    • pumpkin, sweet potatoes, broccoli, nuts/seeds, spinach, tomatoes 
    • RDA: 15 mg/day
  • Copper
    • cashews, white and kidney beans, sunflower seeds, chickpeas, potatoes, spinach, walnuts 
    • RDA: 900 micrograms/day 
  • Iron
    • animal proteins, lentils, chickpeas, nuts, mushrooms, spinach 
    • RDA: Women 18 mg/day. Men 8 mg/day (although vegans/vegetarians/endurance athletes will likely require more) 
  • Phosphorus
    • yogurt, milk, cheese, nuts, seeds, animal proteins 
    • RDA: 700 mg/day 

Dental Issues

Teeth are a living part of your body that require nutrients just like the rest.

They have to be healthy to maintain enamel and prevent tooth decay. Nutrients from food like calcium and vitamin D are vital, so without them, your teeth’s strength and structure can be compromised.

  • Fluoride
    • water, tea, potatoes, legumes, fish, bone broth 
    • RDA: Women 3 mg/day. Men 4 mg/day 

Dry Skin

Vitamin E is important in the healing mechanism of the skin, and protects us from the sun’s harmful UV rays.

Without it, skin starts to appear flaky and dry. It becomes more sensitive to sunlight and more prone to redness and irritation.

Vitamin B3, or niacin, also maintains healthy skin. Without niacin, skin gets rashes, wrinkles, and pigmentation, according to this study.

  • Vitamin B3 (Niacin)
    • water, tea, potatoes, legumes, fish, bone broth 
    • RDA: Women 14 mg/day. Men 16 mg/day 
  • Vitamin B7 (Biotin)
    • nuts, eggs, avocado, salmon, cod, mushrooms, carrots 
    • RDA: 30 micrograms/day 
  • Vitamin C
    • citrus fruits, red peppers, broccoli, tomatoes, brussel sprouts, mango, kiwi
    • RDA: Women 75 mg/day. Men 90 mg/day 

Fertility Issues

In women, low body weight can lead to irregular periods, lack of periods, and infertility. Proteins, vitamins, and minerals help your reproductive system function properly.

Being underweight alters the energy balance needed the menstrual cycle to function properly. In fact, this study confirmed that anorexia and bulimia caused infertility. 

Growth and Development
Problem In Children

We grow the most during adolescence, and boys and girls mature during puberty at different ages.

Malnutrition has serious damaging affects on growth and development as concluded in this study. Children can also become slow, anxious, and have low energy.

Hair Loss

Deficiency in nutrition can impact hair growth. Hair and nails are made of a protein called keratin. If you are eat less calories and lack protein, your body does important functions first.

Functions like digestion and making hormones take priority over hair growth, so hair loss may occur. Find out more in this study.

  • Vitamin B7 (Biotin)
    • nuts, eggs, avocado, salmon, cod, mushrooms, carrots 
    • RDA: 30 micrograms/day 
  • Selenium
    • brazil nuts, animal proteins, fish, garlic, mushrooms, ricotta cheese
    • RDA: 55 micrograms/day 

Weak Bones

Like teeth, bones require calcium and vitamin D to be strong. Malnutrition stunts bone growth and decreases the density of bone.

This puts the structural integrity of your bones at risk and can lead to osteoporosis. 

  • Fluoride
    • water, tea, potatoes, legumes, fish, bone broth 
    • RDA: Women 3 mg/day. Men 4 mg/day 
  • Phosphorus
    • yogurt, milk, cheese, nuts, seeds, animal proteins 
    • RDA: 700 mg/day 
  • Manganese
    • whole grains, nuts, legumes, dark leafy greens 
    • RDA: 11 mg/day

Weak Immune System

Being underweight can lower your ability to fight infection. Our guts rely on sensing nutrients from our diet with immune receptors.

Malnutrition can change gut structure and function, thereby increasing the risk of having an infection.

  • Vitamin C
    • citrus fruits, red peppers, broccoli, tomatoes, brussel sprouts, mango, kiwi
    • RDA: Women 75 mg/day. Men 90 mg/day 
  • Vitamin A
    • organ meats, dairy products, leafy greens, red, yellow, and orange fruits and vegetables. 
    • RDA: Women 700 mg RAE/day. Men 900 mg RAE/day 

Bottom Line 

Your cause for being underweight will determine the steps necessary to achieve a healthier body.

While being underweight has several health risks, there are safe ways to gain weight. 

Getting to the right weight takes time, but you can get there with small steps. For guidance with your nutrition, talk to a dietician or doctor.


Shalom is a content creator, musician, and a teacher at heart. As a certified personal trainer, his goal is to encourage others to lead healthier lives and to get buff in the process!