By now it is common knowledge that being severely overweight puts people at increased risk of suffering from heart disease, stroke and diabetes and that obesity—defined as weighing at least 20 percent more than the high side of normal—is on the rise. According to one estimate, the U.S. will be home to 65 million more obese people in 2030 than it is today, leading to an additional six million or more cases of heart disease and stroke and another eight million cases of type 2 diabetes. Many clinicians have already begun seeing families in which the grandparents are healthier and living longer than their children and grandchildren.

Visualization is courtesy of

As if these alarming figures were not bad enough, studies over the past few years have shown that the obesity epidemic’s true costs extend even further. Research now confirms that excess weight can impinge on mental well-being (exacerbating both depression and Alzheimer’s disease), sexual and reproductive health, and the quality of everyday living—especially as we get older. Scientists believe that perhaps 25 percent of several types of malignancies—including cancer of the colon, kidney and esophagus—are triggered by increasing rates of obesity and physical inactivity.

The consequences, as documented in the images at the right, created by and based on the latest related anatomical data, offer a sobering “anatomical travelogue” of just how far-ranging obesity’s toll on the body can be.

Heartburn: A 2005 study of 450 individuals found that obese adults are two and a half times more likely to experience heartburn compared with people of normal weight. One possible cause: visceral fat may push the stomach higher into the chest.

Labored breathing: Visceral fat, which surrounds internal organs, is more dangerous than subcutaneous fat, which lies under the skin. In this side view, visceral fat presses on the diaphragm from below, which limits breathing by making it harder for the lungs (here shown in green) to expand.

Painful joints: The additional weight of excess pounds places a particular burden on the knees. In this image the arthritic damage (white) triggers pain and a decrease in the knee’s range of motion.

Torso: A cross-sectional view of an obese woman.

Depression: A dozen studies suggest that obesity can be an important cause of depression, possibly because of a combination of physiological factors and social stigma. These neurons, from the cortex of the brain, have shrunk and are misshapen.

Sexual dysfunction: Inflammatory chemicals released by fat cells may damage the branchlike nerves in the penis (above) and attack blood vessels in the clitoris (below), leading to an inability to enjoy sex.

This article was originally published with the title "Five Hidden Dangers of Obesity" in Scientific American 306, 1, 60-61 (January 2012)


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