Persons with obesity are at risk of developing one or more serious medical conditions, which can cause poor health and premature death. Obesity is associated with more than 30 medical conditions, and scientific evidence has established a strong relationship with at least 15 of those conditions. Preliminary data also show the impact of obesity on various other conditions. Weight loss of about 10% of body weight, for persons with overweight or obesity, can improve some obesity-related medical conditions including diabetes and hypertension.
Obesity-Related Medical Conditions
The prevalence of various medical conditions increases with overweight and obesity for men and women as shown in Tables 1 and 2.
|Table 1. Prevalence of Medical Conditions
by Body Mass Index (BMI) for Men
||Body Mass Index
||Prevalence Ratio (%)
|Type 2 Diabetes
|Coronary Heart Disease
|High Blood Pressure
|Source: NHANES III, 1988 - 1994.
|Table 2. Prevalence of Medical Conditions
by Body Mass Index (BMI) for Women
|Type 2 Diabetes
|Coronary Heart Disease
|High Blood Pressure
|Source: NHANES III, 1988 - 1994.
- Maternal obesity (BMI > 29) has been associated with an increased incidence of neural tube defects (NTD) in several studies, although variable results have been found in this area.
- Folate intake, which decreases the risk of NTD’s, was found in one study to have a
reduced effect with higher pre-pregnancy weight.
Cardiovascular Disease (CVD)
Cancers of the Esophagus and Gastric Cardia
- Postmenopausal women with obesity have a higher risk of developing breast cancer. In addition, weight gain after menopause may also increase breast cancer risk.
- Women who gain nearly 45 pounds or more after age 18 are twice as likely to develop breast
cancer after menopause than those who remain weight stable.
- High BMI has been associated with a decreased risk of breast cancer before menopause. However, a recent study found an increased risk of the most lethal form of breast cancer, called inflammatory breast cancer (IBC), in women with BMI as low as 26.7 regardless of menopausal status.
- Premenopausal women diagnosed with breast cancer who are overweight appear to have a shorter life span than women with lower BMI.
- The risk of breast cancer in men is also increased by obesity.
- Obesity is strongly associated with cancer of the esophagus and the risk becomes higher
with increasing BMI.
- The risk for gastric cardia cancer rises moderately with increasing BMI.
Endometrial Cancer (EC)
- High BMI, high calorie intake, and low physical activity are independent risk factors of colorectal cancer.
- Larger waist size (abdominal obesity) is associated with colorectal cancer.
Renal Cell Cancer
- Women with obesity have three to four times the risk of EC than women with lower BMI.
- Women with obesity and diabetes are reported to have a 3-fold increase in risk for EC
above the risk of obesity alone.
- Body size
is a risk factor for EC regardless of where fat is distributed in the body.
- Consistent evidence has been found to associate obesity with renal cell cancer, especially in women.
- Excess weight was reported in one study to account for 21% of renal cell cancer cases.
Carpal Tunnel Syndrome (CTS)
- Obesity increases CVD risk due to its effect on blood lipid levels.
- Weight loss improves blood lipid levels by lowering triglycerides and LDL (“bad”) cholesterol and increasing HDL (“good”) cholesterol.
- Weight loss of 5% to 10% can reduce total blood cholesterol.
- The effects of obesity on cardiovascular health can begin in childhood, which
increases the risk of developing CVD as an adult.
- Overweight and obesity increase the risk of illness and death associated with coronary
- Obesity is a major risk factor for heart attack, and is now recognized as such by the
American Heart Association.
- Obesity has been established as a risk factor for CTS.
- The odds of an obese patient having CTS were found in one study to be almost four times
greater than that of a non-obese patient.
- Obesity was found in one study to be a stronger risk factor for CTS than workplace
activity that requires repetitive and forceful hand use.
- Seventy percent of persons in a recent CTS study were overweight or obese.
Chronic Venous Insufficiency (CVI)
- Patients with CVI, an inadequate blood flow through the veins, tend to be older, male, and
- People with obesity frequently complain of daytime sleepiness and fatigue, two probable
causes of mass transportation accidents.
- Severe obesity has been associated with increased daytime sleepiness even in the absence of sleep apnea or other breathing disorders.
Deep Vein Thrombosis (DVT)
- Obesity increases the risk of DVT, a condition that disrupts the normal process of blood
- Patients with obesity have an increased risk of DVT after surgery.
Diabetes (Type 2)
End Stage Renal Disease (ESRD)
- As many as 90% of individuals with type 2 diabetes are reported to be overweight or
- Obesity has been found to be the largest environmental influence on the prevalence of
diabetes in a population.
- Obesity complicates the management of type 2 diabetes by increasing insulin resistance
and glucose intolerance, which makes drug treatment for type 2 diabetes less
- A weight loss of as little as 5% can reduce high blood sugar.
may be a direct or indirect factor in the initiation or progression of renal
disease, as suggested in preliminary data.
- Obesity is an established predictor of gallbladder disease.
- Obesity and rapid weight loss in obese persons are known risk factors for gallstones.
- Gallstones are common among overweight and obese persons. Gallstones appear in persons with obesity at a rate of 30% versus 10% in non-obese.
- Obesity contributes to the cause of gout -- the deposit of uric acid crystals in joints
- Obesity is associated with increased production of uric acid and decreased elimination
from the body.
- Obesity has been found to be a risk factor for heat injury and heat disorders.
- Poor heat tolerance is often associated with obesity.
Impaired Immune Response
- Over 75% of hypertension cases are reported to be directly attributed to obesity.
- Weight or BMI in association with age is the strongest indicator of blood pressure in
- The association between obesity and high blood pressure has been observed in
virtually all societies, ages, ethnic groups, and in both genders.
- The risk of developing hypertension is five to six times greater in obese adult
Americans, age 20 to 45, compared to non-obese individuals of the same age.
- Obesity has been found to decrease the body’s resistance to harmful organisms.
- A decrease in the activity of scavenger cells, that destroy bacteria and foreign
organisms in the body, has been observed in patients with obesity.
Impaired Respiratory Function
- Obesity is associated with impairment in respiratory function.
- Obesity has been found to increase respiratory resistance, which in turn may cause
- Decreases in lung volume with increasing obesity have been reported.
Infections Following Wounds
- Obesity is associated with the increased incidence of wound infection.
- Burn patients with obesity are reported to develop pneumonia and wound infection with
twice the frequency of non-obese.
- Obesity increases the risk for several reproductive disorders, negatively affecting
normal menstrual function and fertility.
- Weight loss of about 10% of initial weight is effective in improving menstrual regularity, ovulation, hormonal profiles and pregnancy rates.
Low Back Pain
- Excess weight is reported to be an independent risk factor for the development of
alcohol related liver diseases including cirrhosis and acute hepatitis.
- Obesity is the most common factor of nonalcoholic steatohepatitis, a major cause of
progressive liver disease.
- Obesity may play a part in aggravating a simple low back problem, and contribute to a
long-lasting or recurring condition.
- Women who are overweight or have a large waist size are reported to be particularly at
risk for low back pain.
Obstetric and Gynecologic Complications
- Women with severe obesity have a menstrual disturbance rate three times higher than
that of women with normal weight.
- High pre-pregnancy weight is associated with an increased risk during pregnancy of
hypertension, gestational diabetes, urinary infection, Cesarean section and
- Obesity is reportedly associated with the increased incidence of overdue births, induced
labor and longer labors.
- Women with maternal obesity have more Cesarean deliveries and higher incidence of
blood loss during delivery as well as infection and wound complication after
- Complications after childbirth associated with obesity include an increased risk of endometrial infection and inflammation, urinary tract infection and urinary incontinence.
- Bodily pain is a prevalent problem among persons with obesity.
- Greater disability, due to bodily pain, has been reported by persons with obesity compared to persons with other chronic medical conditions.
- Obesity is known to be associated with musculoskeletal or joint-related pain.
- Foot pain located at the heel, known as Sever’s disease, is commonly associated with
- Obesity is a predictive factor of outcome in acute pancreatitis. Obese patients with acute pancreatitis are reported to develop significantly more complications, including respiratory failure, than non-obese.
- Patients with severe pancreatitis have been found to have a higher body-fat percentage and larger waist size than patients with mild pancreatitis.
- Obesity, particularly upper body obesity, is the most significant risk factor for
obstructive sleep apnea.
- There is a 12 to 30-fold higher incidence of obstructive sleep apnea among morbidly obese
patients compared to the general population.
- Among patients with obstructive sleep apnea, at least 60% to 70% are obese.
- Elevated BMI is reported to increase the risk of ischemic stroke independent of other
risk factors including age and systolic blood pressure.
- Abdominal obesity appears to predict the risk of stroke in men.
- Obesity and weight gain are risk factors for ischemic and total stroke in women.
Urinary Stress Incontinence
- Obesity is a risk factor for complications after a surgery.
- Surgical patients with obesity demonstrate a higher number and incidence of hospital
acquired infections compared to normal weight patients.
- Obesity is a well-documented risk factor for urinary stress incontinence, involuntary
urine loss, as well as urge incontinence and urgency among women.
- Obesity is reported to be a strong risk factor for several urinary symptoms after
pregnancy and delivery, continuing as much as 6 to 18 months after childbirth.
- Several other obesity-related conditions have been reported by various researchers
- abdominal hernias, acanthosis nigricans, endocrine abnormalities, chronic hypoxia and hypercapnia, dermatological effects, depression, elephantitis, gastroesophageal reflux, heel spurs, hirsutism, lower extremity edema, mammegaly (causing considerable problems such as bra strap pain, skin damage, cervical pain, chronic odors and infections in the skin folds under the breasts, etc.), large anterior abdominal wall masses (abdominal paniculitis with frequent
panniculitis, impeding walking, causing frequent infections, odors, clothing difficulties, low back pain), musculoskeletal disease, prostate cancer, pseudo tumor cerebri (or benign intracranial hypertension), and sliding hiatil hernia.
Readers should note that researchers have not always used the same criteria to identify overweight and obesity. In this fact sheet, AOA has attempted to use the generally accepted definitions for overweight as a Body Mass Index (BMI) of 25 to 29.9 and obesity as a BMI of 30 or above. We have made an effort to identify studies which have used those specific definitions as well as other scientifically accepted measurements such as waist circumference and waist to hip ratio.