That Spare Tire Can Mean Trouble : Health: Apple-shaped people are at higher risk than those with pear shapes, researchers and doctors are finding.
About once every four times a patient walks into his Manhattan office, Dr. Steven Heymsfield says, the first thought that pops into his mind is: high risk.
The patient is “about 35, obese, with most of the weight in the abdomen,” said the deputy director of the Obesity Research Center at St. Luke’s-Roosevelt Hospital. “The suffering is really in silence--high blood sugar, high cholesterol and high blood pressure--and the results may not show up until (the patient is) 60.”
It was almost 40 years ago that French scientist Jean Vague noted that having more abdominal fat increases the risk for diabetes and cardiovascular disease for both obese men and women. Recently, researchers have linked central obesity to an increased risk of breast and endometrial cancers in women; women who weigh the same but whose excess fat is on their thighs and hips--giving them the pear shape--generally have less to worry about.
“The risk is independent of how fat you are. It has to do with where it is,” said Dr. George Bray, executive director of the Pennington Biomedical Research Center in Baton Rouge, La., an expert in obesity.
This is not to say that the overall health risk is not related to weight: Those who are within the desirable weight range for their age, height and gender--regardless of their body type--have a minimum health danger, Heymsfield said. But for those who are overweight and carry the fat in their middle, the risks are real.
If you are obese and very apple-shaped, your risk of getting diabetes is more than double that of someone who weighs the same but who is very pear-shaped, Bray said. And the risk of heart disease is almost double, he said.
Women who are mildly apple-shaped are at three times higher risk of getting breast cancer than pear-shaped women--the same level of risk that applies to women who have a mother or sister with the disease, according to David V. Schapira, chief of the cancer prevention program at the H. Lee Moffitt Cancer Center & Research Institute at the University of South Florida. Women who are very apple-shaped are at six times the risk--the same as someone who has both a mother and sister with breast cancer.
Although the ways in which central obesity increases risk for these diseases is not fully known, researchers are beginning to understand the different ways our body stores and uses fat. In the long run, this may also provide a key to coming up with a successful long-term weight-loss program--something most weight experts will admit does not exist.
“We really don’t understand how to change body weight or body shape,” said Dr. Rudolph Leibel, an expert on obesity and lipid research at Rockefeller University’s lab on human behavior and metabolism. “The upbeat thing is that we are going to figure it out.”
Obesity is defined as an excess of body fat. Although it is difficult to draw a precise line between being overweight and being obese, a National Institutes of Health panel agreed recently that being 20% or more above desirable body weight “constitutes an established health hazard.”
Dividing your waist circumference by your hip circumference determines whether you are apple- or pear-shaped. Anything less than .75 is considered pear-shaped. If you are .75 to .8, you are mildly apple-shaped; over .8 is considered very apple-shaped.
All fat is not alike. Fat cells in the upper body are larger and less numerous than cells in the buttocks and thighs, according to Schapira, who has published a number of studies on the relationship of abdominal fat to breast and endometrial cancers. When you gain weight, your body adds fat cells and the ones you already have increase in size. When you lose weight, the fat cells simply shrink.
You never lose fat cells--no doubt a reason why dieters have such a hard time keeping weight off. Moreover, the fat cells in the abdomen have the greater potential for shrinkage, whereas the ones in the lower body seem to be designed more for long-term storage, useful to breast-feeding women.
There are other, perhaps even more crucial differences. Abdominal fat deposits itself “viscerally”--inside and around the internal organs--and fat on the thighs and buttocks tends to lie across muscles, Heymsfield said. And the fat in the abdomen seems to be more active biochemically.
Leibel said that one leading hypothesis about how this contributes to diabetes, hypertension and heart disease is this: The fat you have inside your abdomen breaks down fairly quickly--more quickly than the fat in your lower body--releasing fatty acids directly into the blood stream leading to the liver. These high levels of fatty acids change the way some hormones, including insulin, are metabolized.
“Normally, 50% of the insulin released by the pancreas is broken down by the liver,” Leibel said. “This doesn’t happen when you have high fatty acids in the liver. So that means you have more insulin in circulation and have increased synthesis of fats in the liver.”
More insulin circulating eventually can lead to diabetes--an estimated 60% to 70% of late onset diabetes is caused by obesity, Leibel said. And with more fat in the bloodstream, blood lipid levels rise as does blood pressure-- and both are causes of heart disease.
Why abdominal fat seems to increase the risk of breast and endometrial cancer is equally complicated. After menopause, the ovaries no longer produce estrogen, but because estrogen can also be produced in fatty tissues, overweight women continue to have elevated estrogen levels in their blood.
The breast and endometrium are then exposed to greater estrogen levels for a longer period of time; this overstimulation is thought to promote cancer growth. Obese women also produce less sex-hormone binding globulin, or SHBG--which binds with the estrogen, in effect nullifying it--than leaner women.
Schapira and others have found that obese apple-shaped women produce more estrogen and less SHBG than their pear-shaped counterparts, thus putting them at even greater risk for cancer.
