What Is a Weight Gaining Diet?

If you have a body mass index (BMI) of 18.5 or less, you may be underweight. Low body weight can be caused by a number of factors including illness, genetics, medication, psychological issues, or high levels of physical activity. Whether you've experienced some unexpected weight loss or your doctor is recommending you gain weight, it may be time to make some dietary changes that can help you do so.

Following a weight gaining diet increases your daily calorie intake to put on the necessary pounds. The easiest way to increase calories is by eating foods that are energy-dense, which means they're high in calories. 

A weight-gaining diet is not a specific plan with a catchy name or a service promoted by a certain doctor, group, or company. Instead, it is a strategy for increasing the number of calories consumed in order to add weight. It means eating more calories than you burn through exercise and daily activities. This type of diet works whether you are underweight or are specifically trying to build muscle.

What Can You Eat?

To follow a weight gaining diet, simply start by taking in more calories per day than you currently are eating. Carbohydrates are your body's preferred form of energy, and you need to give your body the energy it requires to perform your daily tasks, plus some extra calories.

Increase your carbohydrate intake with whole-grain bread and cereals, fruits, and vegetables, and your overall calorie intake with additional protein and healthy fats.

What You Need to Know

Some foods are better for you than others. It's best to choose those that are high in calories, but also nutritious and good for you. Foods like legumes, avocados, dried fruit, nuts, seeds, nut butter, and smoothies are just a few examples of healthy weight-gaining foods.

You could also increase your calorie intake by eating more junk foods like candy, cake, chips, and sweetened soft drinks. But we don't recommend relying on this method, because they're just not nutritious choices. Other than calories, they don't tend to be high in vitamins, minerals, fiber, or antioxidants either.

This type of diet plan recommends at least three meals every day with larger portions if you have the appetite for it. If you don't feel like eating much, then you might do better with five or six smaller meals eaten more frequently throughout the day.

Sample Meal Plan

Use a meal plan to prepare yourself so you have healthy, high-calorie foods on hand. This sample plan totals about 2,500 calories for one day, which should lead to weight gain for most people. It has a good balance of healthy and high-calorie foods, so you get plenty of nutrients and fiber.

If you need more calories, you can adjust this menu by adding extra snacks or eating larger portions. Note that this is not an all-inclusive meal plan and if you choose to follow a weight gaining diet, you may find that other options for meals work better for you.

Breakfast

• 1 cup oatmeal with 1/2 cup milk and 1/2 cup raisins
• 1 cup of orange juice
• 1 cup black coffee

Morning Snack

• 1 apple and 24 almonds
• Glass of water

Lunch

• Sandwich with 2 large slices of whole-grain bread, 4 slices of lean turkey, 2 tomato slices, lettuce, and mustard
• A 10-ounce glass of reduced-fat milk
• 1 baked sweet potato with a pat of butter or margarine

Afternoon Snack

• 1 protein bar
• Glass of water

Dinner

• Fresh garden salad with 3 tablespoons salad dressing
• 6-ounce salmon filet
• 1 cup cooked spinach
• 1/2 cup mashed potatoes with butter or margarine
• 1 glass of wine (or milk or 100-percent fruit juice)
• 1 whole wheat dinner roll

Nighttime Snack

• 1/2 cup plain yogurt with 1/2 cup sliced strawberries
• Glass of water

Pros and Cons

Because the weight gaining diet is recommended by doctors and nutrition experts, there are many benefits to this diet for those who need to put on weight for better health. Still, there are some drawbacks to this eating plan. Review the pros and cons of this diet plan to determine whether it's right for you.

Pros

Safety

If you need to gain weight, this is a safe way to do it. This diet provides for added calories without artificial supplements or extra sugar, sodium, and unhealthy fats.

Flexibility

Within the parameters of nutrient-rich foods, this diet allows for plenty of free choice in what to eat. If you hate salmon, you never have to eat it. Substitute shrimp or chicken. If you dislike cooked spinach, eat it raw or try a different leafy green instead. Sweets and treats are not banned; they are just not recommended as the main strategy for gaining weight.

Sustainability

If your body continues to need these extra calories, you can keep eating this way indefinitely. Conversely, if you reach a weight-gain goal, you can slowly cut back on calories (say, by eliminating a snack or decreasing portion size a bit) in order to find the balance that works for you.

Cons

Inconvenience

This method of adding healthy calories to gain weight requires planning, shopping, and cooking. It's not as easy as simply adding a daily scoop of ice cream or bag of potato chips to your typical menu.

Battling Your Appetite

If you need to gain weight because you have a low appetite (perhaps due to a medication you are taking), it may be a challenge to do so by eating more food. It can be very difficult to eat when you do not feel hungry.

Is the Weight Gaining Diet a Healthy Choice for You?

A weight gaining diet is very similar to a healthy weight loss diet. In both cases, you will eat foods that are rich in nutrients and not eliminate major food groups. You will avoid "empty calorie" foods (junk foods that contain sugar, salt, and fat, but few other nutrients). The main difference is in the number of calories you consume.

The U.S. Department of Agriculture states that an individual's daily calorie allowance varies based on their current weight, age, sex, health, and activity level.

Often, a 2,000-calorie diet is used as an average. Adding about 500 calories per day to this daily level can help you gain a pound or so per week. This type of gradual change is best. Use this calculator to help you set a daily calorie goal.

Health Benefits

A weight gaining diet is energy-dense and is generally considered a healthy—but you'll want to be sure to choose healthy, whole foods over processed foods whenever possible.

People looking to gain weight may also look to over-the-counter supplements or prescription medications. But weight-gain pills are not necessarily effective or even safe, depending on your particular needs.

Health Risks

While the weight gaining diet is generally healthful and nutritious, it is not always the right course of action for everyone. Obviously, it is not a good idea for anyone who needs to lose weight. It may also not be suitable for people with diabetes or other medical conditions.

A Word from Verywell

Adding extra calories to your day by eating more healthy foods is the best way to gain weight. Although junk foods are high in calories, they don't have the nutritional value and health benefits of nutritious whole foods and don't make the best choices for a weight-gaining diet. A healthy diet is always the best way to add nutrients. Just change your calorie count to help you with your weight management goals.

Remember, following a long-term or short-term diet may not be necessary for you and many diets out there simply don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, and budget, and goals.

If your goal is weight loss, remember that losing weight isn’t necessarily the same as being your healthiest self, and there are many other ways to pursue health. Exercise, sleep, and other lifestyle factors also play a major role in your overall health. The best diet is always the one that is balanced and fits your lifestyle.