Overweight is defined as a body mass index (BMI) greater than or equal to 25.
Obesity is defined as having a BMI greater than or equal to 30.
Severe or morbid obesity is defined as having a BMI greater than or equal to 40.

In children, being overweight or obese is based on BMI being above normal ranges on growth charts.

Overweight is BMI greater than or equal to 85th percentile for gender and age.
Obesity is BMI greater than or equal to 95th percentile for gender and age.
Severe obesity is BMI greater than or equal to 99th percentile for gender and age.

Being overweight or obese occurs when the amount of calories you take in is consistently greater than the number of calories you use during activity and basic bodily functions.

Complications of Obesity

Being obese can increase your risk of early death and shorten life expectancy.

Other complications of untreated obesity include:

Decreased energy
Coronary artery disease (CAD)
Increased risk of blood clots
Increased risk of stroke
High cholesterol and triglycerides in the blood
High blood pressure
Type 2 diabetes
Liver disease
Acute or chronic pancreatitis
Gastroesophageal reflux disease (GERD)
Gallstones
Joint problems, back pain
Increased risk of certain cancers, such as liver, kidney, thyroid, colon, and rectal
Gout
Infertility
Sleep apnea
Poor self-image, depression

Being overweight can also affect pregnancy and your child.

Some pregnancy complications include:
- High blood pressure during pregnancy—preeclampsia
- Gestational diabetes
- Depression during your pregnancy
- Depression after your baby is born—postpartum depression

Effects on children may include increased risk of:
- Diabetes
- Obesity
- Birth defects, especially neural tube defects
- Autism or other neurodevelopmental disorders

You may also experience problems during labor and delivery, or have a baby with a high birth weight.

References:

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Obesity. Merck Manual Professional Version website. Available at:
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Update December 2016. Accessed February 23, 2017.

Obesity and overweight. World Health Organization website. Available at:
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Updated June 2016. Accessed February 23, 2017.

Obesity in adults. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115009/Obesity-in-adults. Updated November 20, 2016. Accessed February 23, 2017.

Overweight and obesity. National Heart, Lung, and Blood Institute website. Available at:
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Updated February 23, 2017. Accessed February 23, 2017.

Zaman A. Diabetes and obesity greatly contribute to hepatocellular carcinoma. NEJM Journal Watch website. Available at:
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Accessed October 1, 2013.

10/16/2009 DynaMed Plus Systematic Literature Surveillance http://www.dynamed...: Krul M, van der Wouden JC, Schellevis FG, van Suijlekom-Smit LW, Koes BW. Musculoskeletal problems in overweight and obese children. Ann Fam Med. 2009;7(4):352-356.

1/15/2010 DynaMed Plus Systematic Literature Surveillance http://www.dynamed...: Shiri R, Karppinen J, Leino-Arjas P, Solovieva S, Viikari-Juntura E. The association between obesity and low back pain: a meta-analysis. Am J Epidemiol. 2010;171(2):135-154.

5/27/2014 DynaMed Plus Systematic Literature Surveillance http://www.dynamed...: Molyneaux E, Poston L, Ashurst-Williams S, Howard LM. Obesity and mental disorders during pregnancy and postpartum: A systematic review and meta-analysis. Obstet Gynecol. 2014;123(4):857-867.

10/1/2014 DynaMed Plus Systematic Literature Surveillance http://www.dynamed...: Bhaskaran K, Douglas I, Forbes H, dos-Santos-Silva I, Leon DA, Smeeth L. Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5.24 million UK adults. Lancet. 2014;384(9945):755-765.

Last reviewed February 2017 by Michael Woods, MD, FAAP
Last Updated: 2/23/2017

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