BMI Calculator for Underweight

BMI and Being Underweight

Knowing what BMI is and why it matters for your health is important to understand its relationship with weight. You are considered underweight if your BMI is under 18.5. The normal BMI range is between 18.5 and 24.9.

A lower BMI indicates a lack of nutrients in your body, putting you at a risk of developing health issues like anemia, osteoporosis, reproductive problems, etc. You can use the BMI calculator or the formula below to know your BMI:

BMI = Weight (kg) ÷ Height (m²)

Here is the BMI range for your reference:

Weight Class

BMI Range

Underweight

BMI less than 18

Normal Weight

BMI between 18.5 to 24.9

Overweight

BMI between 25 to 29.9

Obese (all classes)

BMI 30 and above

Compare the resulting value from the underweight BMI calculator with the BMI chart to check your weight category and take health-related actions accordingly. Just as it is important for overweight people to reduce BMI naturally, it is crucial for underweight individuals to increase their BMI safely for better health.

The BMI calculator for underweight females and the BMI calculator for underweight men are the same, as the BMI calculation method is the same across the globe.

Why Being Underweight is Unhealthy?

You are considered underweight if your BMI is less than 18.5. The BMI calculator for underweight allows them to easily track their weight category over a specified time period. If you have been consistently underweight, it can lead to the following health problems:

Malnutrition

Weakened immune system

Chronic fatigue

Anaemia

Osteoporosis

Reproductive issues

Surgical complications

Slow growth

MalnutritionBeing underweight is directly related to malnutrition. If the body does not receive enough nutrients and calories, it can lead to reduced fat and muscle mass, thereby resulting in unhealthy weight loss. A low BMI is an indicator for low weight, putting the underweight individual at a higher risk of malnutrition.

Weakened Immune SystemIndividuals with a low BMI often lack essential nutrients and their immune system may become less effective. It means a low white blood cell (WBC) production when the body needs to fight foreign infectious bodies, resulting in the person falling severely or repeatedly ill.

Chronic FatigueIf the body gets insufficient calories, it will have less energy to distribute across the body than the required amount for smooth functioning. This can make an underweight person feel tired all the time.

AnaemiaUnderweight people usually have a low red blood cell count as they do not get adequate iron, resulting in persistent dizziness and headaches. You can reduce iron deficiency by maintaining a healthy BMI through adequate calorie intake.

OsteoporosisInsufficient vitamins and minerals can weaken the bones. Excessive bone density loss and low muscle mass can put underweight people at an increased risk of developing osteoporosis, a severe bone disease where bones become significantly brittle and prone to fractures.

Reproductive IssuesPeople with low BMI often face problems with reproductive health and infertility. Underweight women often experience more irregular or delayed periods. Moreover, maintaining optimal BMI during pregnancy can be challenging for underweight women, increasing complications in conceiving and other pregnancy-related risks.

Surgical ComplicationsUnderweight people are usually at a higher risk of complications during or after surgeries. This is because their bodies are weaker and more prone to infections. They may also take more time to recover.

Slow GrowthChildren and young people have a developing body, and hence need more nutrients. Insufficient calories in underweight people can result in slow or impaired growth. Knowing how to calculate BMI for children and teens is essential, as the calculation method differs from that for adults.

How to Increase BMI Safely for Underweight Individuals?

It is essential for underweight individuals to gain weight to reduce health risks. Keep a tab on whether you have reached the optimal weight using the BMI calculator for underweight people. It is also vital to follow a systematic plan to gain weight without any sudden side effects.

You can start by making healthy lifestyle changes, such as increasing your calorie intake, adding nuts, dried fruits, cheese and peanut butter to your meals, building a regular fitness routine and getting enough sleep. If you have been consistently underweight for a long time, you must consult a doctor for a complete health assessment. To learn more about how to increase BMI safely if you are underweight, read this article.

FAQs

Q1. What is your BMI if you are underweight?

Ans: If your BMI is less than 18.5, you are considered underweight.
Q2. Is BMI 17.7 underweight?

Ans: Yes. A BMI of 17.7 is less than the starting point of the normal BMI range (18.5), and hence falls into the underweight category.
Q3. How do I calculate if I'm underweight?

Ans: To calculate if you are underweight, use the BMI formula, which is:
BMI = weight (kg) ÷ height (m²)
If the answer is less than 18.5, you are underweight.
Q4. How to fix an underweight BMI?

Ans: You can fix an underweight BMI by ensuring safe weight gain. For this, you must add more carbohydrates, protein and fats to your diet. Include nuts, seeds, high-fat dairy products, whole grains, etc. in your diet.
Q5. What is the BMI for a 5 ft 2 in female?

Ans: The BMI for a 5 ft 2 in female depends on her weight. For her BMI to be in the normal range, it should be between 18.5 and 24.9. This means that her weight should be between 47 and 59 kgs.

FAQs

Q1. What is your BMI if you are underweight?

Q2. Is BMI 17.7 underweight?

Q3. How do I calculate if I'm underweight?

Q4. How to fix an underweight BMI?

Q5. What is the BMI for a 5 ft 2 in female?