Health Update

by Tyrone M. Reyes, M.D.

Having a large middle is not just a cosmetic issue — it’s a health threat. The excess fat tissue that makes it tough to tighten your belt also encases your abdominal organs, secreting hormones, inflammatory chemicals, and fatty acids that increase your risk of heart disease, high blood pressure, insulin resistance, type 2-diabetes, and possibly some cancers. Many scientists now believe that a wide waist circumference may be a better predictor of health risks than a battery of blood tests. But this is one risk factor you can do something about. Because abdominal or visceral fat (see figure) is more metabolically active than the fat that sits on your hips and thighs, it is easier to lose. The best way to trim it is a combination of diet and increased aerobic exercise.

A major study of more than 27,000 people from 52 countries, drawn from diverse ethnic and racial groups, found that those people with the largest waist were 75 percent more likely to suffer a heart attack compared to those with the narrowest waistline. At the same time, this study, which was published in the November 2, 2005 issue of The Lancet found that a high body mass index (BMI) was a less accurate predictor of cardiovascular risk. Even among men of normal weight, heart disease risk was higher for those with big bellies. So all you may need to judge your future risk of a heart attack is a measuring tape!

A more recent study, published in the December 15, 2006 issue of the American Journal of Epidemiology further bolstered this belief. Men with the largest waistline were found to be 42 percent more likely to develop heart disease. The figure is even higher in women (44 percent). The study’s conclusion: The more your belly sticks out, the greater your risk of developing heart disease. “The message is really that obesity in the abdomen matters even more than obesity overall,” says Dr. Carlos Iribarren of Kaiser Permanente of Northern California, the study’s lead author.

Fat Is Active, Not Passive

Recent research has revealed that fatty tissue is not an inert blob, but an endocrine organ, and a surprisingly active one, helping to regulate many metabolic functions. Fat cells are stuffed with droplets of triglycerides — fats that are constantly being broken down into free fatty acids and released into the blood stream. Normally, the body burns free fatty acids as fuel (along with glucose). But when you have too many large fat cells and a high triglyceride level, it leads to an excess of free fatty acids. The fatty acids secreted by visceral fat go straight to the liver, where they affect cholesterol and triglyceride production. Elevated triglycerides in the blood also contribute to fatty plaques that narrow coronary arteries; the rupture of these plaques causes blood clots, which block the artery and can lead to a heart attack.

The Diabetes Connection

Triglyceride levels are also influenced by our ability to respond to insulin. Insulin is the hormone that helps break down food into energy (in the form of glucose) and brings it into the cells for fuel. When tissues don’t respond properly to insulin, they are not able to use glucose as fuel so glucose levels build up in the blood. To compensate, triglyceride levels rise, and more free fatty acids are produced for fuel instead.

Fat cells secrete a hormone called adiponectin, which reduces blood glucose by blocking its production by the liver and increases its burning by muscles. Another hormone produced by fat cells is called resistin, which makes body tissues more resistant to insulin. New research suggests that adiponectin production in visceral fat decreases as we gain weight in the abdomen. In contrast, adiponectin production increases when we gain fat cells in the hips and thighs. So, a pear shape is less dangerous than an apple shape.

Scientists in Israel and Sweden recently discovered a possible mechanism by which elevated fats contribute to insulin resistance and type-2 diabetes. They found a receptor on insulin-producing cells in the pancreas (beta cells) that responds to fatty acids. When there are excess fats in the blood in addition to elevated glucose, these receptors signal beta cells to pump out more insulin, the scientists reported in the April 2005 issue of Cell Metabolism. Chronic stimulation may exhaust beta cells, eventually reducing insulin output and leading to type-2 diabetes.

Other Reasons Belly Fat Is Bad

Belly fat is also a source of inflammation, notes Louis J. Aronne, MD, director of the Weill Cornell Comprehensive Weight Management Program. Visceral fat is studded with immune cells called macrophages, which pumps out inflammatory chemicals. “Excess visceral fat attracts white blood cells which become activated, leading to increased inflammation elsewhere in the body,” explains Dr. Aronne. Obese people have bigger fat cells that are even more metabolically active and secrete more inflammatory chemicals. Obesity itself may even be one of the root causes of chronic disease, coronary disease, cancer, and diabetes,” adds Dr. Aronne.

Excess fat also produces chemicals that make blood clots form and constrict blood vessels, raising blood pressure, says Robert H. Eckel, MD, president of the American Heart Association. “Obese people have more high blood pressure, more pulmonary hypertension, and deep vein thrombosis,” asserts Dr. Eckel.

Out With Belly Fat

Fortunately, visceral fat is very responsive to diet and exercise, says Dr. Laszlo Tanko, MD, of the Center for Clinical and Basic Research in Ballerup, Denmark. If you’re apple-shaped, have a waistline bigger than 35 inches, and elevated triglycerides, weight loss through diet and exercise is highly recommended to reduce the increased risks. “Although it sounds simple and repetitive, we believe this is the most effective way of eliminating the source of the problem. Luckily, upper body fat mass responds relatively rapidly to diet and exercise changes. The challenge is to maintain these benefits and obtain a lasting prevention,” says Dr. Tanko. Research shows that even a 10 percent weight loss can reduce risk factors.

You can’t get rid of visceral fat — or its risks — with liposuction. Liposuction only removes fat deposits under the skin (subcutaneous fat). A study published in June 2005 in the New England Journal of Medicine found that even after up to 20 pounds of subcutaneous fat was removed from the abdominal area with liposuction, there was no effect on risk factors such as insulin resistance. But if the person loses weight through diet and exercise, the first area of fat to be reduced is belly fat, Dr. Aronne points out. When you lose abdominal fat, your risk of metabolic syndrome is also reduced.

Don’t despair if the peripheral fat deposits on your hips and thighs don’t respond as well to diet and exercise. Peripheral fat actually produces more adiponectin, notes Dr. Tanko. Women are genetically programmed to store fat in these areas, but after menopause, fat deposits shift to the abdomen.

“A woman who has enlarged waist and elevated triglycerides is very likely to have an apple shape, predominantly upper body fat accumulation, and relatively underdeveloped lower body fat. When you don’t have enough peripheral fat, you lose an important defense system,” remarks Dr. Tanko. “Fat stores in the hips and thighs may actually be protective because adiponectin increases insulin sensitivity in fat and muscle cells. And it helps rid the body of the dangerous metabolites that promote atherosclerosis.”

What You Can Do

So here’s what you can do to reduce visceral fat and your risks of heart disease, stroke and diabetes:

• Choose an eating plan that suits you and make it part of your life to lose or maintain weight.

• Increase exercise to 60 minutes a day (you can break it up into small segments).

• Keep track of your waist size, and make sure it stays well below 35 inches.

Remember, the bigger the belly, the higher the health risk.

Source: Philippine Star