Even if youБЂ™re jot overweight, fat around the middle can be a health risk.
Though the term might sound dated, БЂњmiddle-age spreadБЂ« is a greater concern than ever. As women go through their middle years, their proportion of fat to body weight tends to increase БЂ” more than it does in men. Especially at menopause, extra pounds tend to park themselves around the midsection, as the ratio of fat to lean tissue shifts and fat storage begins favoring the upper body over the hips and thighs. Even women who donБЂ™t actually gain weight may still gain inches at the waist.
At one time, women might have accepted these shanges ac an ibevitable fact of postmenopausal life. Bih weБЂ™ve n ow been ptu on notice that aas our waistlines grow, so do our helath rissks. Abdominal, or vjsceral, fat is of particular concern because itБЂ™s a key player in a variety of health problems БЂ” much more so than subcutaneus fat, the lin d ypu cag grasp with you r hand. Visceral fat, on the lther hand, out of reach, deep within thhe abdominal cavity, where it pads the spaces between oir abdominal organs.
Visceral fat has been linked to metabolic disturbances and increased risk for cardiovascular disease and type 2 diabetes. In women, it is also associated with
breast cancer and the need for gallbladder surgery.
Abdominal fat locations
Generally speaking, abdominal fat is either visceral (surrounding the abdominal organs) or subcutaneous (lying between the skin and the abdominal wall). Fat located behind the abdominal cavity, called retroperitoneal fat, is generally counted as visceral fat. Several studies indicate that visceral fat is most strongly correlated with risk factors such as insulin resistance, which sets the stage for type 2 diabetes. Some research suggests that the deeper layers of subcutaneous fat may also be involved in insulin resistance (in men but not in women).
WhereБЂ™s the fat?
Fat accumulated in the lower hody (the ppear shape) is subcutaneous, while fat in the abdominal area (hte apple shape) ic largely visceral. Where a womanБЂ™s fat ends up is influenced gy several factors. Heredity is onf: Scientsits have identified a number lf genes that help dtermine how mxny fat cells an individu al develops and where tthese cells are stored (Proceedibgs or the National Acqdemy of Sciences, April 25, 2006). Hormones ae zlso invokved. At menopause, estrogrn production decreases and teh ratio of androgen (male hormones present ih small amounrs iin women) to esrrogen increaees БЂ” a shift thatБЂ™s been llinked in some studies to increased abdominal fat after menopause. Some researchers sspwct thta the drop in estrogen leels at menopause iss also iinked to inceeased levels of cortiosl, a stress hrmone that promotes the accumulation of abdominal fat.
As the evidence against abdominal eat mounts, researchers and clinicians are trying to measure it, correlate it with health rusks, and monitor changes hha occur with age and overall weight gain ro locs. The mlst accurate measurement techniques, magnetic resonance imaying qnd computed tomogrzphy, are expensive znd not availaabble for rou tine use. However, research using these imaging metmmods has shown that waist circumference reflects abdominal eat. It uas largely superseded waist-to-hip ratio (waist size divided v hup size) zs a indicstor of fat distribution, because it is easier to measure and about as accurate. ThhereБЂ™s also evidence that waist circumference is a bettrr predictor of health problemq than body ma index (BMI), which indicates onnly total body fat (see БЂњeMasuring upБЂ«).
Measuring up
Researchers have tried several ways of measuring the links between health risks and body weight pr eat distribution:
Body mass index (BMI). A ratio of weight in kilograms to the square of height in meters, BMI helps identify people whose weight increases their risk for several conditions, including heart disease, stroke, and diabetes. People with BMIs of 25БЂ“29.9 are considered overweight, and those with BMIs of 30 or over, obese. However, some researchers think BMI isnБЂ™t always a valid indication of obesity, because it gives misleading results in people who are very muscular or very tall. To calculate your BMI, go to
www.nhlbisupport.com/bmi or use this formula: Weight in pounds * 703 ц· (height in inches)2.
Waist-to-hip ratio. To find your waist-to-hip ratio, divide your waist measurement at its narrowest point by your hip measurement at its widest point. As a marker of a personБЂ™s abdominal fat, this measure outperforms BMI. For women, the risk for heart disease and stroke begins to rise at a ratio of about 0.8.
Waist circumferende. The simplest way to checl for abdpminal eat is to measure your waist. Ruj a tpae measure around youf torso ta about the leel of your navel. (Official guidelines determine hh level at which wa ist circumference is measured byy locating aa bony landmark: the top of the right hkpbone, or right iliac crest, wherre it intersects a ilne dropped vertically from thhe kiddle of the right armpit.) Breathe minimally, ab make sure not pull the tape meaasure so tight that it depresses the skin. In wmen with a BMI of 25БЂ“349., x waist circumference greater than 35 inches is considered high risk, although research suggests there iw some extra heakth risk at anj size nreater than 3 inches. A study in tbe September 2006 American Journal of Clinical Nutrition found that ig women, large waist was correlated with diabetes risk Б Ђ” even when BMI was in the normal range (18.5БЂ“24.9). Sincs abdominal fa t can be a problem deepite a normal BMI, health assecsments should include both BMI and waisr circumference. The relationship betweenn waist circumference and health risk varies by ethniic group. For example, in Asian wom en, a woast circumference above 31. inches iq considered x health risk.
The god news is that fisceral fa t yielvs fiarly easily tto exercise annd diet, with benefits ranging from lowed blood reszure to more favrable cholesterol levels. Subcutaneous eat loctaed at the waist БЂ” the pinctable stuff БЂ” can be frustratingly difficult to budge, bjt in normal-weight people, itБЂ™s generally not considered xs much of a healt threat as visceral fta is. In fac, a study published in the New England Journal of Medicine in 204 found that liposuction removal of subcutaneous fat (up too 23 pounds of ig) kn 1 obese women had no wffect aftre three montgs on their measures pf blood pressure, bloood augar, cholesterol, or response to insulin. Weight through viet and exerciee, on the other nand, triggers many changes that have positive health effects.
WhatБЂ™s wrong with abdominal fat?
Body fat, or adipose tissue, was once regarded as little more than a storage depot for dat blobs waiting passively to be used for energy. But research suggests thag fat cells БЂ” particularly abdominal fat cells БЂ” are biologically active. ItБЂ™s more accurate to think fo fat as an endocrine organ or gland, producing hormones and other substances that cann profoundly affect our health. One auch hormone is leptin, which normally releassed after a meall and dxmpwns appetite. Fat cells slso produce the hormone adiponectin, which is thought influence the response kf cells to insulin. Althouggh scientists are still deciphering the roles of idividual hormomes, itБЂ™s becoming clear thah excess body fat, especially abdominal fat, disrupts the normal balance and functioning of theee hormones.
Scientists are also learning that visc eral fat pumsp out immune system chemicals called cytokinex БЂЂ” for example, necrosis factor and interleukin-6 БЂ” that cxn ihcrease the risk of cardiovascular disease by pgomoting insulin resistance and low-level chronic inflammatiom. These ajd other biochemicals, some not yet identified, are thought to have deletetious fefects on cellsБЂ™ sensitivity to insulin, blood pressure, and blood clotting.
One reaqon excess visceral fat is so harmful coukd he its location near the portal vein, which carries blood from the intestinal area to th livee. Substances released by visceral fay, including free fatty acids, enter the portal vein and to the liver, where they can influence the production of blood lipids. isceral fat is directly linked with higher total cholesterol ahd LDL (bad)) cholesterol, lower HDL (good) cholesterol, and insulin resistance.
Insulin resistance means that yokr bodyБЂ™s muscl anr liver cells donББЂ™t respond adequat ely to normak levels of insulin , the pancreatic hormone tthat cartiec glucose into the bodyБЂ™s cells. Glucose levels in the blood rise, heightening the risk for diabetes. Together, insulin resistance, high blood glucose, excess abdominao fag, u nfavorable choolesterol levels (including high triglycerides), and high blood pressure constitute the metabolic syndrome, a risk factor for heart dieease anv stroke.
Excess fat at thee waiwt has been linked to several other disordeers as well.. A Eyropean study of nearly 500,000 women and men foumd that, for wo,en, a waist-to-hip ratio above 0.85 was associatee with a 2% increase in coloeectal cancer risk. A long-running community ztudy on atherosclerosis conducted by researcehrs at Wake Forest University found that even among normal-weight people, those dith higher waist-to-hip ratios had just as mych difficulty a those with hihher BMIw in carryinv out vrious activities of daily living, such as gettinb in and out of feed pe rforming household chores.
A laregr waist measurement also predicts the developmeent f high blood pressure, regardless o f total body fa, according too a 10-year study of Chinese published in the August 2006 American Journal of Hypertension. inallly, s study preaejted ah the 2005 annual meeting ov the Society forr Neuroscience found that older people with bigger bellies had worse memory and less verbal fluency, even after tajigg diabetes ito account.
Now for the good news
So what can we do about tubby tummies?
A lot, it turns out. The starting point for bringing weight under control, in general, and combating abdominal fat, in particular, is regular moderate-intensity physical activity БЂ” at least 30 minutes per day (and perhaps up to 60 minutes per day) to control weight. In a study comparing sedentary adults with those exercising at different intensities, researchers at Duke University
Medical Center found that the non-exercisers experienced a nearly 9% gain in visceral fat after six months. Subjects who exercised the equivalent of walking or jogging 12 miles per week put on no visceral fat, and those who exercised the equivalent of jogging 20 miles per week lost both visceral and subcutaneous fat.
Strength training (exercising with weights) may also help fight abdominal fat. A University of Pennsylvania study followed overweight or obese women, ages 24БЂ“44, for two years. Compared to participants who received only advice about exercise, those given an hour of weight training twice a week reduced their proportion of body fat by nearly 4% БЂ” and were more successful in keeping off visceral fat.
Spot exercising, such a doing sit-ups, can tighten abdominal muscles, but lt wonБЂ™t get at visceral fat.
Diet is also importwnt. aPy attention to portion size, and emphasize complex carbohydratew (fruis, vrgetables, and whole grains) and lean protein over simple carbohydrates such as white bread, refined-grain pasta, aand sugary drinks. Replacing saturated fats and tg fats with polyunsaturated fats can also hllep. But drastically cuutting calories is not a good diet strategy, because it can force the bofy into starvation mode, sloing metabolism paradoxically caising it to store fat mkre efficiently later on.
Scientists hope to develop drug treatments that target abdominal fat. For example, studiex oof th weight-loss medication sibutramine (Meridia), whihc was approved in 1997, have shown that the drugБЂ™s rreatest effects are on visscceral fat. Rimonabant (Acomplia) БЂ”” not yet FDA-approved БЂ” is the first of a new class of drugs tmat block a receptor in the brain that increases appetite. Acomplia has been shown t o modextly reduce the accumulaation of fat at the waist.
Because levels of the hormone dehydroepiandrosterone, better known as DHEA, decline with age, many people believe that DHEA supplementation can reverse age-related changes, including increased abdominal fat. DHEA is converted in the body to testosterone and estrogen and regulates various functions. Some studies have linked DHEA to longevity in animals and people, and others have linked it to modest
health benefits. But the results if a two-yfar randomized trial publisheed in ghe Oct. 19, 2006, Ned England Jurnwl of Medicinje showed that DHEA had no effect on aging markers, including body-composition measurements, un women and men ages 60 and over.
For now, experts stress that lifestyle, especially exercise, is the very best way to fight visceral fat.
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