Researchers poke holes in 'obesity paradox'

The “obesity paradox” suggests that people who are overweight or obese and diagnosed with cardiovascular disease (CVD) live longer than those with normal weight. A group of researchers debunked that theory, publishing their findings online Feb. 28 in JAMA Cardiology.

“In recent years, controversy about the health implications of overweight status has grown, given findings of similar or lower all-cause mortality rates in overweight compared with normal-weight groups,” wrote lead author Sadiya S. Khan, MD, with Northwestern University Feinberg School of Medicine in Chicago and colleagues. “However, current studies have not taken into account the age at onset and duration of cardiovascular disease, limiting the ability to account for proportion of life lived with CVD morbidity in individuals who are overweight and obese compared with normal weight. This is especially important because disease burden associated with development of CVD results in less healthful years of life, poorer quality of life, and increased healthcare expenditures.”

Using the Cardiovascular Disease Lifetime Risk Pooling Project, the researchers sought to calculate the lifetime risk incident CVD and subtypes, and estimate the years lived with and without CVD by weight in more than 190,000 people. The study cohort did not exhibit signs of CVD when they were first monitored, and they were followed for 10 years. The cohort was grouped by age and weight status.

The researchers compared risks for cardiovascular disease, including heart attack, heart failure and stroke among men and women aged 40 to 50, who had various weights.

Some of the chief findings were:

  • Obesity is associated with reduced longevity, with an increase in cardiovascular morbidity and mortality, compared to individuals with normal body mass index (BMI).
  • Those who are overweight have a similar lifespan to those of normal weight but have a higher risk of developing CVD at a younger age.
  • Risk for cardiovascular ailments was 21 percent higher in overweight men, and 67 percent higher in obese men, compared to normal-weight men.
  • Risk for cardiovascular ailments was 32 percent higher in overweight women, and 85 percent higher in obese women, compared to normal-weight women.
  • Obese men lived 1.9 years less than normal-weight men and there was little difference in longevity between overweight and normal-weight men.
  • Obese women lived 1.4 years less than normal-weight women and obese women lived 3.4 years less than normal-weight women.

“These results provide critical perspective on CVD associated with overweight and obesity and challenge both the obesity paradox as well as the view that overweight is associated with greater longevity,” the authors concluded.