The following is an excerpt from the new book The Obesity Paradox: When Thinner Means Sicker and Heavier Means Healthier by Carl J. Lavie (Penguin Books, 2014):
Similar to how the famous French paradox points to an inverse relationship between the incidence of coronary heart disease and the consumption of saturated fats, the so-called “obesity paradox” points to an inverse relationship between body fat and risk of death in many cases. While it’s well-documented that obesity has contributed to our challenges with chronic illness, and that exercise is often a surefire antidote, no one has explained some of the stranger cause-and-effect reactions going on deep within our cellular makeup that have everything to do with fat’s positive side. It’s pretty straightforward: Fat isn’t always bad. And exercise isn’t always good.
These are hardly inconsequential findings. The fact that body fat protects us in a lot of surprising ways—not to mention may help us live longer after a grim diagnosis or heart attack—has been quiety circulating in our most prestigious medical literature for the past few years.
As the studies about the benefits of fitness despite the presence of fatness (a “fit- fat” paradox) were coming into view, so, too, were hints that obesity as an absolute evil condition begged to be reconsidered. As a prelude to our detailed discussion of the obesity paradox, let me showcase a relatively recent study that’s tested conventional health wisdom for its surprising, unassailable evidence that obesity isn’t always bad.
In 2012, a report from the Swedish Coronary Angiography and Angioplasty Registry made international headlines with data from more than sixty-four thousand patients that featured a most counterintuitive and unlikely relationship: Once people have developed heart disease, they have a reduced risk of dying if they are overweight or obese, while underweight and normal-weight patients have an increased risk.
The researchers evaluated patients who had developed heart problems such as unstable angina (chest pain caused by an inadequate blood supply to the heart) and heart attacks, and at those who underwent coronary angiography, a special X- ray test to discover detailed information about the condition of their coronary arteries, between May 2005 and December 2008. Patients who were underweight (BMI of less than 18.5) had the greatest risk of dying—double that of normal- weight patients, who had BMIs between 21 and 23.5. Compared to the group with lowest risk of mortality, meaning those with BMIs of 26.5 to 28, underweight individuals had three times the risk of death. The researchers also found that the relationship between BMI and mortality was U-shaped. In other words, those with the lowest risk of death were overweight and obese patients, with BMIs ranging from 26.5 to about 35; and the highest risk resided among underweight and morbidly obese patients, those with a BMI above 40.
While many of us struggle daily with constant thoughts about losing weight (and how we’re going to do that), especially if we’ve been diagnosed with a “weight- related” condition such as heart disease, these researchers dared to suggest that there’s no evidence to prove that weight loss helps someone who has a heart condition. They were even bold enough to say that there’s evidence to show that weight loss after the diagnosis of a heart condition might in fact have a negative effect, particularly for those who have a BMI less than 40. I personally feel that purposeful weight loss, when done in a healthy manner and with good intentions, is safe despite the obesity paradox. There is some evidence from small studies that show such weight loss can be safe and beneficial, but we have yet to collect substantial data from large studies proving the benefits of weight loss on cardiac patients and in terms of overall survival, especially in people with established heart disease.
So if you have to choose between being fit or fat, go for fit even if it means being heavier. As I’ve already mentioned, many people lose fitness and gain fatness with aging. The good news is that if you gain weight as you age, your health can still be excellent so long as you remain fit. And we’re not talking about super- high levels of fitness, either. You just need to avoid being in the bottom twentieth percentile for fitness given your age and gender.