What are the health risks of overweight and obesity?

Overweight and obesity raise the risk of many serious diseases and health conditions.^1-11 Obese adults have at least a 20% higher risk than normal weight adults of death from cardiovascular disease and all other causes.³ Disease and health conditions associated with overweight and obesity include:^1-11

• Hypertension
• Cholesterol problems such as high LDL cholesterol, high triglycerides, and low HDL cholesterol
• Type 2 diabetes (T2DM)
• Cardiovascular disease (CVD) such as atherosclerosis, heart attack, stroke, and heart failure
• Nonalcoholic fatty liver disease
• Obstructive sleep apnea
• Acid reflux disease
• Asthma
• Osteoarthritis
• Some types of cancer such as breast, uterine, colon, kidney, gallbladder, and liver
• Polycystic ovary syndrome
• Female infertility
• Male hypogonadism (low testosterone)
• Alzheimer’s disease and dementia
• Mental health problems such as depression and anxiety

Definition of Overweight and Obesity

Overweight and obesity were most recently defined in the 2013 guidelines for the management of overweight and obesity in adults by The Obesity Society and American College of Cardiology/American Heart Association (ACC/AHA).⁵ Overweight is defined as a body mass index (BMI) of 25.0 to 29.9 and obesity as a BMI of ≥30 [Strong Recommendation (Level B)). BMI is a measure that adjusts body weight for height.

In the US, about 70.7% of adults age 20 or older are overweight (BMI ≥25) (age-adjusted prevalence).¹² Of these, 39.8% are obese (BMI ≥30). These estimates are based on an analysis of the 2015 – 2016 US National Health and Nutrition Examination Survey (NHANES).

Study Details for Overweight and Obesity-Related Health Risks

Obese adults have at least a 20% higher risk of death than normal weight adults from CVD and all other causes.³ The rates in this 2014 study are based on the Third NHANES data (1988 – 1994) with follow-up linked to the 2006 National Death Index mortality file (n=16,868). The study found the rates of all-cause death were advanced by 3.7 years for adults with BMI ≥35. Obese adults may die earlier from CVD causes than people with normal weight, ranging from 1.6 years early (95% confidence interval [CI] [0.1 – 3.1]) for mildly obese to 5.0 years early (95% CI [1.7 – 8.4]) for severely obese (BMI ≥40). A 2009 analysis of United States nationally representative health surveys, such as NHANES 2003 – 2006, and US disease-specific mortality statistics found that about one in ten deaths in the US, or about 216,000 adults (95% CI [188,000 – 237,000]) could be attributed to overweight and obesity.⁴ In the same analysis, they found that hypertension (regardless of weight status) accounted for one in five to six deaths, or about 395,000 adults (95% CI [372,000 – 414,000]).

A systematic review and meta-analysis of 25 studies with a total of 2,274,961 participants found an increased risk of ischemic stroke for overweight (RR 1.22, 95% CI [1.05 – 1.41]) and obese (RR 1.64, 95% CI [1.36 – 1.99]) people versus normal weight participants.¹⁰

A 2009 meta-analysis of 89 studies found statistically significant associations between overweight (BMI ≥25 – 29.9) and obesity (BMI ≥30) and the incidence of T2DM, hypertension, stroke, coronary artery disease (CAD), osteoarthritis, gallbladder disease, asthma, pulmonary embolism, chronic back pain, and cancer of the breast, ovaries, endometrium, colon, and kidney.⁷ Risks details follow:

^{*IRR (incidence rate ratio); RRP (relative risk calculated from the ration of proportions)}

ꜜ^{Postmenopausal women}

A cohort study of 5.24 million people age 16 years or older with no previous cancer diagnosis in the past 12 months looked at the incidence of 22 types of cancer in people who never smoked.⁶ The authors found that excess weight (BMI ≥25) could account for 41% of uterine cancer and at least 10% of colon, kidney, liver, and gallbladder cancers.

^References

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