Can being overweight or obese cause high blood pressure?

Overweight and obesity are associated with the development of many serious diseases and health conditions including hypertension.^1-7 Risk estimates suggest that 65% to 75% of essential hypertension in adults is related to overweight and obesity.^8-11 For example, the Framingham Offspring Study followed 4,294 adults ages 20 – 49 years for eight years.¹⁰ The study found a risk estimate of essential hypertension attributable to excess weight and visceral obesity of 77.9% in men and 64.4% in women.¹⁰ In the Framingham Heart Study, 9,845 normotensive adults (mean age 52 years) were followed from 1978 to 1994 and assessed at four-year intervals. The study concluded that a 5% weight gain raised the odds of developing hypertension by 20% to 30%.¹²

A 2009 meta-analysis of four studies found statistically significant associations between overweight (body mass index [BMI] ≥25 – 29.9) and hypertension.⁶

• Overweight: incidence rate ratio [IRR] 1.28, 95% confidence interval [CI] [1.10 – 1.50] for men and IRR 1.65, 95% CI [1.24 – 2.19] for women
• Obesity: IRR 1.84, 95% CI [1.51 – 2.24] for men and IRR 2.42, 95% CI [1.59 – 3.67] for women

Okosun et al. used data from the third US National Health and Nutrition Examination Surveys (1988 – 1994) to estimate the prevalence of abdominal obesity and its association with hypertension.¹³ They found the risk of hypertension to be two to three times higher in this population than in people with normal waist size. Abdominal obesity was defined as waist circumference (WC) ≥102 cm for men and WC ≥88 cm for women. Hypertension was defined as systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg or current treatment with an antihypertensive medication. This study found that the population attributable risk for hypertension in people with abdominal obesity was:

Obese people have excess adipose tissue that requires increased blood flow to support it.^11,14 This increase is not limited to the excess tissue. Obesity results in an increased total blood volume, stroke volume, and cardiac output, while peripheral vascular resistance is increased.^11,14-16 Obese people often have insulin and leptin resistance which can lead to sodium retention which contributes to the hemodynamic dysfunction and elevated blood pressure. In obese people, the heart rate itself is usually not increased so the higher cardiac output is mainly managed by a higher stroke volume. This results in increased filling pressure and volume. This increased blood pressure further contributes to heart damage including left ventricular dilation, wall stress, and hypertrophy. It can also cause the left atrium to enlarge. The kidneys may also be damaged by the increased pressure.

Obese adults have at least a 20% higher risk of death than normal weight adults from cardiovascular disease (CVD) and all other causes.³ Obese adults may die earlier from CVD causes than people with normal weight, ranging from 1.6 years early (95% CI [0.1 – 3.1]) for mildly obese to 5.0 years early (95% CI [1.7 – 8.4]) for severely obese (BMI ≥40) people.³ A 2009 analysis of US 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

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 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.

An Adult BMI Calculator is available from the US Centers for Disease Control and Prevention.¹⁷ It is for people 20 years old or older.

^References

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