Overweight & Health
Effects
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.
Medical Conditions
The prevalence of various
medical conditions increases with overweight and obesity for men and women as shown in Tables 1 and 2.
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Table 1. Prevalence of Medical Conditions
by Body Mass Index (BMI) for Men
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Medical Condition
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Body Mass Index
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18.5 to 24.9
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25 to 29.9
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30 to 34.9
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>
40
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Prevalence
Ratio (%)
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Type 2
Diabetes
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2.03
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4.93
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10.10
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10.65
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Coronary
Heart Disease
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8.84
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9.60
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16.01
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13.97
|
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High
Blood Pressure
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23.47
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34.16
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48.95
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64.53
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Osteoarthritis
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2.59
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4.55
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4.66
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10.04
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Source:
NHANES III, 1988 - 1994.
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Table 2. Prevalence of Medical Conditions
by Body Mass Index (BMI) for Women
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Medical Condition
|
Body Mass Index
|
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18.5 to 24.9
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25 to 29.9
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30 to 34.9
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>
40
|
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Prevalence
Ratio (%)
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Type 2
Diabetes
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2.38
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7.12
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7.24
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19.89
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Coronary
Heart Disease
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6.87
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11.13
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12.56
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19.22
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High
Blood Pressure
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23.26
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38.77
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47.95
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63.16
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Osteoarthritis
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5.22
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8.51
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9.94
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17.19
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Source:
NHANES III, 1988 - 1994.
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Arthritis
Osteoarthritis (OA)
Obesity is associated with
the development of OA of the hand, hip, back and especially the knee.
At a Body Mass Index (BMI) of
> 25, the incidence of OA has been shown to steadily increase.
Modest weight loss of 10 to
15 pounds is likely to relieve symptoms and delay disease progression of knee OA.
Rheumatoid Arthritis (RA)
Obesity has been found
related to RA in both men and women.
Birth Defects
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.
Cancers
Breast
Cancer
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.
Cancers
of the Esophagus and Gastric Cardia
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.
Colorectal Cancer
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.
Endometrial Cancer (EC)
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.
Renal
Cell Cancer
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.
Cardiovascular Disease
(CVD)
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 heart disease.
Obesity is a major risk
factor for heart attack, and is now recognized as such by the American Heart Association.
Carpal Tunnel Syndrome
(CTS)
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 have obesity.
Daytime
Sleepiness
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 clotting.
Patients with obesity have an
increased risk of DVT after surgery.
Diabetes (Type 2)
As many as 90% of individuals
with type 2 diabetes are reported to be overweight or obese.
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 effective.
A weight loss of as little as 5% can reduce high blood sugar.
End Stage Renal Disease
(ESRD)
Obesity may be a direct or
indirect factor in the initiation or progression of renal disease, as suggested in preliminary
data.
Gallbladder
Disease
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.
Gout
Obesity contributes to the
cause of gout -- the deposit of uric acid crystals in joints and tissue.
Obesity is associated with
increased production of uric acid and decreased elimination from the body.
Heart Disorders
Obesity has been found to be
a risk factor for heat injury and heat disorders.
Poor heat tolerance is often
associated with obesity.
Hypertension
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 humans.
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.
Impaired Immune
Response
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 breathlessness.
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.
Infertility
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.
Liver Disease
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.
Low Back Pain
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 toxemia.
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 surgery.
Complications after
childbirth associated with obesity include an increased risk of endometrial infection and inflammation, urinary
tract infection and urinary incontinence.
Pain
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.
Pancreatitis
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.
Sleep Apnea
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.
Stroke
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.
Surgical Complications
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.
Urinary Stress Incontinence
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.
Other Health
Disorders:
Several other obesity-related
conditions have been reported by various researchers including:
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.
Note:
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.
American Obesity Association
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