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The Dangers of Being Underweight

By Kuebi = Armin Kübelbeck (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons

A lot of attention is paid to obesity, but not much thought is given to those who are underweight. Those who have a Body Mass Index (BMI) of 18.5 or under are medically classified as being underweight. Some of the main reasons why someone could be underweight includes the following; malnutrition, stress, depression, abuse, dental or oral problems and having an eating disorder.

Immune System

Being underweight can cause serious issues with a person’s immune system and weaken it. What this basically means is that the body is not receiving enough nutrients and it can wind up making one more susceptible to viruses, diseases and infections. Without adequate nutrition, a body will cannot function properly. In order to have a healthy immune system, vitamins A and C are very important and being underweight could mean the body won’t have enough reserves to prevent illness. Lowered immunity makes it hard for someone to fight off sickness, but adding nutrient dense foods into your diet can help you become healthier, gain weight and strengthen your immune system.

Body Temperature Changes

Many times people will associate feeling cold with an eating disorder, but anybody who is underweight may have difficulty controlling and regulating their body temperature. With a healthy body weight, you have insulation that will keep your body warm. However, someone who is underweight for any reason may feel cold or have a chill, even if it is warm outside. By gaining a few pounds, a person can counteract feeling cold all the time and it can aid in helping the body maintain a normal temperature.

Nutritional Deficiencies

Those who are underweight are often at an increased risk for nutritional deficiency issues. Sometimes a person who is underweight may be deficient in calcium and potassium, which are vital to bone and heart health. Nutrient deficiencies can also cause problems with lung function, mental health, joints and digestion.

Decreased Energy

If a person’s body does not have enough fat and stores of nutrients, it can wind up making them feel weak and sluggish. Lacking energy can make it hard for a person to get through the day and perform their tasks and responsibilities. This condition is likely due to lacking iron in the blood, which is a nutrient that helps prevent anemia. By simply including some iron rich foods in your diet, it can help increase the amount in the blood and give you more energy.


Women are more likely than men to be overweight. Females who are underweight can experience problems with menstruation. It could wind up causing infertility down the road because the body cannot regulate your hormones and it can cause ovulation to become irregular. In order to be healthy and fertile, a woman must put on weight and do it in a healthy way.


It is just as important to address the health dangers of being underweight, as it is to address the ones associated with obesity. If you have a friend or loved one who is too thin, watch the person’s health and if you become concerned, speak up and let them know you are worried there may be a problem.