You may have heard you should cut back on fat and eat plenty of carbs to reduce your risk of heart disease. What you might not have heard is that this diet, recommended by most health experts, may actually make things much worse.

In his aptly titled book, Syndrome X: Overcoming the Silent Killer That Can Give You a Heart Attack, Gerald Reaven, M.D., an endocrinologist at Stanford University, warns that certain individuals may be setting themselves up for a heart attack instead of preventing one by following such a diet.

Reaven claims that heart disease is not just a product of hardening arteries. He says it can also stem from a little-known cluster of metabolic abnormalities that he has coined Syndrome X, a condition of elevated triglycerides (blood fats); low HDL (or "good") cholesterol levels; unusually small, dense particles of LDL ("bad") cholesterol; and high insulin levels.

Although all the conditions associated with Syndrome X contribute to heart disease to some extent, Reaven believes it's the excess insulin in the bloodstream that causes most of the damage. The reason for this excess is that people with Syndrome X are resistant to their own insulin, so the body requires more of it and, ultimately, more damage is done to the heart.

Most of the damage actually originates in the liver. Instead of ushering glucose into its cells to use for energy, as muscle and fat cells do, the liver responds to insulin by releasing triglycerides into the blood. Although this is a normal response and won't do much harm in an otherwise healthy person, the effects can be downright lethal to someone with Syndrome X. The constant elevation in insulin levels cause the liver to produce more and more triglycerides, which elevates blood levels and increases the risk of heart disease.

Insulin resistance may also encourage spontaneous, unnecessary blood clots to form in the coronary arteries, stopping the flow of blood and triggering a sudden heart attack. Elevated insulin levels seem to make blood vessels more narrow and less elastic as well, which forces the kidneys to retain sodium and water. This raises blood pressure and eventually the odds of atherosclerosis (hardening of the arteries).

You may have heard about insulin resistance before. In fact, most fad diet gurus have sensationalized Reaven's research to promote the notion that insulin makes you fat. Reaven, however, distances himself as much as he can from these high-protein, low-carb crusaders. He emphasizes in Syndrome X that insulin resistance doesn't make you fat. If you're overweight or obese, the likelihood of developing insulin resistance simply increases. What's more, insulin or carbohydrates themselves can't make you fat. Extra calories, no matter where they come from, are what cause weight gain.

So, could you have Syndrome X? It's hard to say. Reaven and his colleagues agree it's about 50 percent genetic, but the rest is up to you, particularly how much you weigh, how often you exercise, and what kind of diet you follow. For a diagnosis, you'll need to go to the doctor for a few routine blood tests to measure your glucose tolerance, triglycerides and HDL cholesterol.

For someone who meets the criteria for insulin resistance, Reaven recommends losing weight (if appropriate), increasing physical activity, stopping smoking, and moderating alcohol consumption. Medical intervention, such as medications, may be necessary for some people. Most importantly, he urges those diagnosed with Syndrome X to change their diet to one consisting of 45 percent carbohydrate, 15 percent protein, and 40 percent fat (mostly poly- and monounsaturated fats).

These recommendations fly in the face of the American Heart Association's (AHA) suggestions to prevent heart disease: 55 to 60 percent carbohydrate, 15 percent protein, and 30 percent fat. According to Reaven, carbs need to be scaled down because the more carbohydrates an insulin-resistant person eats, the more insulin the pancreas must secrete to prevent the blood glucose from climbing too high.

The AHA, however, won't be changing their recommendations anytime soon. Although they agree that people with Syndrome X are at an increased risk for heart disease, the AHA believe further studies are needed to understand the complex relationship between all of these risk factors and appropriate recommendations.

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