Why is extra fat dangerous? Scientists now say that fat, technically called adipose tissue, is more than a passive fuel dump. Rather, it is robust tissue that releases hormones and other internal chemicals. And too much fat triggers an immune response, a highly organized effort by the body to rid itself of a foreign invader. Here’s the simplified reasoning: Unlike healthy-weight people, those who are overweight or obese have fat cells that are supersize and more likely to burst, leaving behind a glob of fat in your bloodstream. The body treats this fat glob as an invader and sends out an army of macrophages, inflammatory proteins whose job it is to destroy the invader. A chronic state of inflammation causes the body’s natural protective mechanisms to go a little haywire, potentially leading to problems such as insulin resistance (in which insulin no longer adequately clears the glucose out of your bloodstream), diabetes and heart disease (inflammation seems to contribute to the thickening of artery walls), explains Donald Hensrud, MD, associate professor of preventive medicine and nutrition at the Mayo Clinic in Rochester, Minnesota.
The particular issue for women is that much of the weight gained in mid-life lands in your belly, and this visceral fat, rather than the fat in your thighs and hips, is most strongly correlated to the inflammatory process and potential disease. That’s why, according to research, a waist size of 35 inches or more puts you at an increased risk for some medical conditions, such as type 2 diabetes, high cholesterol, high blood pressure and cardiovascular problems.
One culprit behind women’s widening middles may be the declining estrogen levels in midlife. In a series of animal experiments, Deborah Clegg, PhD, assistant professor of internal medicine at the Touchstone Diabetes Center at the University of Texas, Southwestern, and her colleagues showed that specific estrogen receptors in our brain influence how much we eat, how we use this food as fuel and where our extra fat winds up residing. In one study, female mice whose receptors had been reduced or silenced ate more food than they had before. Their metabolic rates also plummeted, so they did not burn the calories as quickly as usual. The end result: Those
mice packed on the weight.
Even worse than losing their figures, the mice also developed impaired glucose tolerance, an indication of prediabetes. “The hormone estrogen,” Clegg says, “protects us from metabolic problems like diabetes.”
The good news While prediabetes is serious, a fairly small weight loss—about five to seven percent of body weight—along with 30 minutes of moderate exercise, such as walking, most days of the week, can help bring blood glucose levels under control and reduce the risk of diabetes down the road. And a 20 percent drop in your weight can reduce your risk of heart disease.
Culprit No. 2
The more weight you carry, the more wear and tear there is on your joints, which can lead to their premature breakdown, says Lisa Cannada, MD, spokesperson for the American Academy of Orthopaedic Surgeons and associate professor of orthopedic surgery at Saint Louis University Hospital. Think basic physics. According to the Johns Hopkins Arthritis Center, if you weigh just 10 extra pounds, the force you place on your knees increases by as much as 30 to 60 pounds with each step you take.
Numerous studies have shown a link between being overweight or obese and the development of the aches and pains of the most common form of arthritis, osteoarthritis. Osteoarthritis can affect the hands, shoulders, lower back and neck, but it’s the hips and knees that take the brunt of the additional weight.“The heavier you are, the higher your risk of developing osteoarthritis in the knee,” says David Felson, MD, professor of medicine and epidemiology and principal investigator of the Multidisciplinary Clinical Research Center at Boston University. This means that women in the overweight category have an increased chance of developing knee osteoarthritis than those with a normal BMI. But overweight women still have less of a risk than obese women.