Health Effects of Obesity


Persons with obesity are at increased risk of developing 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. 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.

Arthritis (Osteoarthritis)

  • Obesity is associated with the development of Osteoarthritis (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.


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.



  • 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 Oesophagus and Gastric Cardiac
    • Obesity is strongly associated with cancer of the esophagus and the risk becomes higher with increasing BMI.
    • The risk for gastric cardiac 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.


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.


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.


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.


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.



  • 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.



  • 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

  • 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.


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.



  • 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