How Much Weight Can You Lose Before Your Body Starts to Shut Down?

The lowest weight before death varies, as every individual has a different body size and composition. Body mass index, or BMI, is one way to estimate if an individual is underweight. A BMI under 16 is associated with an increased risk of death, warns the World Health Organization.

The specific amount of weight you can lose before your body starts to shut down varies, as each individual is different. Credit: Coolpicture/iStock/GettyImages

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The specific amount of weight you can lose before your body starts to shut down varies, as each individual is different. A body mass index under 18.5 indicates that an individual is underweight. When BMI is below 16, health risks, including the risk of death, are increased.

Body Mass Index

Body mass index is calculated by dividing your weight in kilograms by your height in square meters. You can also calculate BMI by dividing your weight in pounds by your height in square inches and multiplying this value by 703. While this measurement does not directly measure body fat or muscle mass, it has been shown to have a strong correlation with body fat measurements, according to the Centers for Disease Control and Prevention.

The BMI value represents your general body condition. The BMI chart for both males and females over 20 years of age is as follows:

  • BMI 30 or above: Obese

  • BMI

    25 to 29.9: Overweight

  • BMI

    18.5 to 24.9: Normal weight

  • BMI

    Below 18.5: Underweight

While a higher BMI typically indicates a higher body fat percentage, individuals with the same BMI may have different levels of body fat. In general, women will have more body fat than men, and older individuals have more body fat than those who are younger.

In the United States, most health organizations focus on the consequences of being overweight and having an elevated BMI. However, being underweight can also cause health concerns and, in severe cases, cause the body to shut down completely.

Read more: Health Risks of a Low BMI

The World Health Organization notes that a BMI value under 17 is considered moderate to severe thinness, and it's linked to an increased rate of illness. When this number drops below 16, weight loss is extreme and health risks increase noticeably. At this level, individuals become lethargic, have poor physical performance and may face death.

Weight Loss Causes

Severe weight loss has many possible causes. One mental condition that's known to cause extreme weight loss is anorexia nervosa. This eating disorder is most common in women in their teenage years and early adulthood, according to Ohio State University.

Individuals with this disorder severely limit their food intake to avoid weight gain. Some common anorexic thought patterns include an extreme fear of weight gain and the idea that the individual is overweight when they are not.

In addition to weight loss, other symptoms of anorexia include:

  • Obsession with exercise and calorie counting
  • Hiding food to avoid eating
  • Being secretive about eating
  • Hair loss
  • Pale or gray skin tone
  • Loss of menstrual cycle
  • Low blood pressure
  • Feeling cold
  • Insomnia
  • Mood swings and low self-esteem

Other conditions and circumstances may cause weight loss too, including a poor diet and a lack of available food. Certain medical conditions can affect the body's ability to properly absorb the nutrients from food, resulting in weight loss.

Some of these conditions include:

  • Celiac disease
  • Whipple disease
  • Short bowel syndrome
  • Lactose intolerance

Certain medications may also prevent nutrient absorption.

Warning

If you have symptoms of anorexia or unexplained weight loss, contact your doctor immediately, as it may be a sign of a serious medical condition.

Stages of Anorexia Before Death

As weight loss progresses and reaches a critical level, multiple body systems begin shutting down. Some signs of the body shutting down from anorexia include fainting, bluish coloring on tips of fingers and ears, irregular heartbeat, yellow skin and an inability to regulate body temperature, according to Dr. Jane Mitchell Rees of the University of Washington.

Read more: Signs & Symptoms of Starvation Mode

Other complications of anorexia may affect nearly every system in the body, as reported in a March 2015 review in the Journal of Eating Disorders. Potential cardiovascular symptoms include prolapse of the mitral valve, abnormally slow heart rate and low blood pressure. Potential metabolic complications include thyroid abnormalities, hypoglycemia, irregular or lost period, infertility and neurogenic diabetes insipidus.

Potential dermatological complications include dry skin, languno hair, alopecia and severe itching. As anorexia progresses, individuals may be more prone to fissures and bleeding in the skin. Gastrointestinal complications include constipation and hepatitis. Individuals may also experience bone loss and a loss of brain tissue, or cerebral atrophy.

Warning

Ammenoria, or loss of a woman's period, is a warning sign that you have lost a dangerous amount of weight.

Men suffering from eating disorders don't have a comparable warning sign. Typically, men have a lower percentage of body fat, so dangerous complications may appear with far less weight loss, notes the Journal of Eating Disorders.

Symptoms become more severe as the body begins to shut down. In the final stages of starvation before death, symptoms include bloody diarrhea, fluid and electrolyte imbalance causing both edema and dehydration, and severe cardiac arrhythmia.

Treating Starvation and Anorexia

In cases where an individual is severely underweight and malnourished, hospitalization is necessary to stabilize the patient. Medical supervision and nutritional counseling may be necessary as food is reintroduced into his diet.

During treatment, underweight individuals are at risk of developing refeeding syndrome, which results in electrolyte imbalances and deficiencies, as well as related complications including arrhythmia, muscle weakness, respiratory failure, coma and death. There is no standard treatment for refeeding syndrome, but options may include a slow increase in caloric intake and extensive electrolyte monitoring.

If the individual is unable or unwilling to eat the recommended food, doctors may prescribe a liquid formula to provide the needed nutrition. In extreme cases, a feeding tube may be utilized.

Doctors will also want to treat the underlying cause of extreme weight loss. In the case of anorexia, this includes mental healthcare to address the eating disorder. Treatment options include psychotherapy and antidepressant medications. This is critical to an individual's recovery, as they fear gaining weight, but must do so in order to survive.

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