Concerns about weight are not limited to being overweight or obese. Problems surrounding this topic can also arise when someone falls into the underweight category.

Just as overweight or obesity can affect physical health, mental wellbeing, and fertility, being underweight can have similar health consequences to people. Let’s look at what underweight means and how to address it safely.

What Does Underweight Mean?

Body Mass Index (BMI) is used to classify whether you are underweight, at a healthy weight, overweight, or obese. BMI is calculated as weight (kg) divided by height (m) times height (m).

Here are the BMI categories:

• Underweight: a value below 18.5
• Normal weight: a value between 18.5 and 24.9
• Overweight: a value between 25.0 and 29.9
• Obesity: a value above 30

If your BMI is less than 18.5, you are considered underweight.

Health Effects of Being Underweight

Being underweight is linked to a number of health issues, including:

• Vitamin deficiencies
• Osteoporosis
• Compromised immune function
• Worsened fertility
• Problems affecting the skin, hair, and teeth
• Getting sick more easily
• Persistent fatigue
• Anemia
• Increased risks of complications during surgery
• Irregular menstrual cycles
• Risk of preterm birth
• Delayed or impaired growth

A study published in BMC Public Health also reported that underweight status is associated with a higher risk of death compared with those who have an average BMI.

Other researches further show that people who are underweight may heal more slowly after injuries or accidents.

How to Gain Weight if You’re Underweight

Being underweight does not mean you should eat very large portions every day. Weight gain should be approached thoughtfully to avoid creating other health problems.

Try these healthy, safe strategies to increase weight:

• Eat more often. If you are underweight, you may feel full quickly. Aim for 5–6 smaller meals spaced throughout the day. This is often more effective than eating 2–3 large meals.

   

• Choose nutrient-dense foods. Prioritize whole grains, fruits, vegetables, nuts, seeds, and dairy products.

   

• Make juices or smoothies. Blend milk with frozen fruit to create smoothies, and consider adding seed toppings.

   

• Add healthy fats. Include sources like olive oil and avocado, sprinkle cheese over dishes, and mix milk powder into drinks, soups, or stir-fries.

• Watch your drinking schedule. Avoid drinking water right before meals, since it can reduce your appetite. Opt for more nourishing or higher-calorie beverages between meals, during snacks, or about 30 minutes after eating.

• Pick healthy snacks. Select calorie-dense options with healthy fats, such as nuts, cheese, or dried fruit.

   

• Boost meals with extra toppings. Add items like eggs or cheese to many dishes to increase total calories.

• Exercise. Choose strength-focused routines, such as weight training, to build muscle. Beyond toning and strengthening your body, exercise can stimulate appetite and make you feel hungrier.

Some individuals with a family history of being very lean, chronic medical conditions, or mental health concerns may face more complex challenges with low weight.

See your doctor for a test and discuss a personalized plan to help you gain weight safely and healthily, based on your medical background.

Looking for information about nutrition, food and other diet tips? Click here!