What Is Morbid Obesity?

Reviewed by Melinda Ratini, DO, MS on June 03, 2021

Obesity is determined by your body mass index (BMI). This score is calculated by finding your height and weight on the BMI chart. Morbid obesity is defined by a BMI of 40 or greater.

Understanding Body Mass Index

When you use a BMI chart to determine how healthy your weight is, you’ll find a corresponding number to your height and weight:

  • If you have a BMI of less than 18.5, you are in the underweight range.
  • If you have a BMI of 18.5 to less than 25, you are in the healthy weight range.
  • If you have a BMI of 25.0 to less than 30, you are in the overweight range.‌
  • If you have a BMI of 30.0 or higher, you are in the obesity range.

Additionally, you can divide obesity into three separate categories of severity:

  • Obesity class 1: BMI between 30 and less than 35
  • Obesity class 2: BMI between 35 and less than 40‌
  • Obesity class 3: BMI of 40 or higher

This class of obesity is also categorized as “severe” obesity. Generally speaking, you are morbidly obese if you are 100 pounds heavier than your recommended weight. You may also be considered morbidly obese if you have a BMI of 35 or more and have obesity-related health conditions like high blood pressure or diabetes.

Risks of Morbid Obesity

If you are morbidly obese, you may also experience health conditions like:

  • Lower life expectancy – Being overweight leaves you at risk for not living as long as if you were in a healthy weight range. 
  • Type 2 diabetes – Obesity may lead to insulin resistance, creating inconsistent blood sugar levels that your body cannot maintain without the help of medication and diet changes. 
  • Hypertension and heart disease – Too much weight adds stress to your heart, and it cannot function properly to circulate oxygen through your body. In addition to high blood pressure, you may also be at risk for strokes and damage to your heart and kidneys.
  • Osteoarthritis – Added weight causes your joints to wear down faster, especially around your hips and knees. Over time, chronic inflammation leads to permanent damage and decreased mobility.  
  • Problems breathing – Added fat in your neck may block your airways, leading to sleep apnea and respiratory problems. 
  • Gastroesophageal reflux disease – Excess weight means that the valve at the top of your stomach cannot function to keep acid in your stomach. If acid rises from your esophagus, you may experience frequent heartburn. 
  • Depression – This condition can take a toll on your mental health. Add in the stress of multiple health conditions, and depression becomes a prevalent concern. 
  • Infertility – Weight affects your reproductive organs and hormone levels, making it difficult to conceive.‌
  • Urinary stress incontinence – Pressure on your kidneys and bladder weaken your muscles, making it more difficult to hold your urine if you laugh, cough, or sneeze. 

Diagnosing Morbid Obesity

If you have any of the above-listed health conditions, talk to your doctor about your concerns. It’s never too late to get help and take your life back. Share your history with diet, exercise, and efforts to maintain your weight or lose weight.

Include any eating patterns, eating disorders, or family history that may have contributed to morbid obesity. It’s important to bring up all aspects of your lifestyle so your doctor has a clear picture of your needs and can prescribe a treatment plan to help you achieve a healthy weight.

During a physical exam, your doctor:

  • Measures your weight and height to calculate BMI
  • Checks your vital signs, including blood pressure, heart rate, and breathing
  • Measures your waist circumference‌
  • Completes blood tests to check for the signs of health conditions like diabetes

Keep in mind that your waist size is also tied to increased health risks. Women with a waist size greater than 35 inches and men with a waist size of more than 40 inches are at a higher risk for health problems.

Treating Morbid Obesity

When your BMI reaches levels that exceed obesity and reach morbid obesity, weight loss is increasingly difficult. Only around 5% of people who fall in the morbidly obese range are successful at losing weight without surgical assistance.

Working with a certified professional to develop a plan that works for you increases your chances of success. Most of the time, insurance companies won’t pay for weight loss surgery unless you first try to lose weight on your own.

Diet. You may start by eating less calories than you burn, but do so with the guidance of a medical professional to make sure you're still getting enough nutrition. This results in weight loss of one to two pounds per week. Keep in mind that you should focus on eating healthier instead of following a trendy diet scheme. Become familiar with reading ingredient labels, and reach for whole, unprocessed foods.

Exercise. You also want to add in physical activity every day. If you need to start small, that’s okay. Walk up and down your street, or park in the back of the parking lot when you go shopping. Take the stairs instead of the elevator when you have the option.

Behavioral therapy. Sometimes old habits are so deeply set in the mind, it can be hard to change them alone. With a therapist's help, you can change harmful habits into healthy ones to promote weight loss. This is an excellent choice for identifying patterns of thought, improving emotional coping mechanisms, and working through mental health issues.

Medication. If you are struggling with the desire to eat more than your allotted calories for the day, your doctor may suggest a medication that blocks fat absorption or acts as an appetite suppressant. This may help increase your success early on and produce results that are sustainable long-term. However, keep in mind that these may have side effects, and it's common to gain back weight after going off of them.

Surgery. If none of these things help sufficiently, you may need surgery to lose enough weight to reach a healthy BMI range and no longer be considered morbidly obese. Bariatric surgery works by sealing off most of your stomach, so you feel fuller faster. When you have to eat less food and feel full on less food, you lose weight faster. Remember that weight and health changes don't happen overnight, so give it plenty of time before considering this method unless otherwise advised by your doctor.

Show Sources


CDC: “Defining Adult Overweight & Obesity.”

Mayo Clinic: “Obesity.”

University of California San Francisco Health: “Obesity Treatment.”

University of Rochester Medical Center: “What is Morbid Obesity?”

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