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Health Effects of Obesity
Obesity is a chronic disease resulting from a complex interaction of genetic, physiological, metabolic, behavioral, cultural, and social factors. People with obesity are at increased risk for developing serious medical conditions and disease. These medical conditions impact overall health and well-being, and contribute to the risk of premature death. Obesity is now considered the leading cause of preventable death in this country.
Obesity has been clearly established as a major risk factor for hypertension, cardiovascular disease, type 2 diabetes, some cancers, and osteoarthritis. Higher body weights are also associated with an increase in mortality from all causes. An increase in body weight that is 20 percent or more of a healthy weight is considered to be a health hazard. Even lower levels of excess weight can be a health risk, especially when other conditions such as diabetes, hypertension, and heart disease are present.
Studies suggest that people with mental retardation are at higher risk for obesity than the general population. While there are some genetic causes of mental retardation such as Down Syndrome and Prader-Willi Syndrome that are associated with obesity, it is generally believed that sedentary lifestyles may contribute to this higher rate of prevalence.
Medical Conditions Related to Overweight and Obesity
The Body Mass Index (BMI) is a measure commonly used by health care professionals to determine total body fat. BMI is a mathematical computation derived from multiplying a person’s weight in pounds by 703 and then dividing by the height in inches squared. (To calculate BMI, go to http://www.nhlbisupport.com/bmi/bmicalc.htm or refer to the BMI chart included in the article this month for Regional Center staff.)
Clinical judgment must be used when interpreting a BMI score but the following classifications for BMI scores are commonly used:
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Underweight
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BMI less than 18.5
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Healthy weight
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BMI 18.5 to 24.9
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Overweight
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BMI 25 to 29.9
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Obesity (Class 1)
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BMI 30 to 34.9
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Obesity (Class 2)
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BMI 35 to 39.9
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Extreme Obesity (Class 3)
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BMI greater than 40
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The prevalence of different medical conditions progressively increases with higher BMI scores for men and women overweight or obese as reflected in the tables below.
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Prevalence of Medical Conditions by Body Mass Index (BMI) for MEN
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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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| Diabetes (Type 2) |
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 |
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 |
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 |
2.59
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4.55
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4.66
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10.04
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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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| Diabetes (Type 2) |
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 |
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 |
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 |
5.22
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8.51
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9.94
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17.19
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Diabetes
- The vast majority (80-90%) of people with type 2 diabetes are overweight or obese.
- Obesity may complicate the management of type 2 diabetes as drug treatment is often less effective.
- A weight gain of 11 to 18 pounds doubles the risk for type 2 diabetes.
Coronary Heart Disease
- Overweight and obesity increases cardiovascular disease due to its effect on blood lipid levels.
- Weight loss improves blood lipid levels by increasing HDL cholesterol, decreasing LDL cholesterol and triglycerides.
- Small amounts of weight loss can reduce total blood cholesterol.
High Blood Pressure
- BMI in association with age is the strongest indicator of high blood pressure.
- At least one third of all cases of high blood pressure can be attributed to obesity.
Osteoarthritis
- Osteoarthritis of the hand, back, hip, and knee is associated with obesity.
- The risk for developing osteoarthritis increases by 9 to 13% for every two pounds of weight gained.
- Modest weight loss (10 – 15 pounds) is likely to relieve symptoms and delay progression of osteoarthritis in the knee.
- Women are more likely than men to develop osteoarthritis.
Stroke
- An elevated BMI increases the risk of ischemic stroke independent of other risk factors including age and systolic blood pressure.
- Abdominal obesity appears to predict stroke risk in men.
Cancer
- Breast cancer: women who gain more than 20 pounds from age 18 to midlife are twice as likely to develop breast cancer after menopause as women whose weight remains stable.
- Endometrial cancer: women with obesity have three to four times the risk of endometrial cancer than women with lower BMI. Women with both obesity and diabetes have a much greater risk.
- Colorectal cancer: high BMI and low physical activity are risk factors for colorectal cancer. Colon cancer occurs more frequently in people who are obese, especially men.
- Cancers of the esophagus and gastric cardia: obesity is strongly associated with cancer of the esophagus; people who are overweight or obese run a risk that is double that of those who do not have a high BMI. The risk for gastric cardia cancer rises with increasing BMI.
Other Conditions
- Gall bladder disease: obesity increases the risk of gall bladder disease. Gallstones are common among persons who are overweight and obese.
- Liver disease: obesity has been identified as the leading cause of chronic liver disease. Non-alcoholic fatty liver disease occurs in almost two-thirds of people with obesity.
- Breathing problems: obesity is a significant risk factor for obstructive sleep apnea. The majority of people with sleep apnea are obese. Obesity is also associated with a higher prevalence of asthma.
- Carpal tunnel syndrome: obesity is a risk factor for carpal tunnel syndrome. One study found that the risk was four times greater in people with obesity as compared to people with lower BMI.
- Menstrual disturbance: women with obesity are three times more likely to have some form of menstrual disturbance than women with normal weight.
- Pain: obesity is associated with musculoskeletal pain or joint-related pain. Foot pain located at the heel is commonly associated with obesity.
- Bladder control problems: obesity is a risk factor for urinary stress incontinence, involuntary urine loss, and urgency incontinence among women.
Sources: Centers for Disease Control and Prevention, National Center for Health Statistics; American Obesity Association; National Institutes of Health, National Heart, Lung, and Blood Institute, and National Institute of Diabetes and Digestive and Kidney Diseases.
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