If you’ve struggled with weight control for most of your life as I have, you’ve probably gotten advice from doctors to avoid fats in your diet for better vascular health.  A new study suggests that low-fat diets may not do much at all for vascular health, however, except to get in the way of weight reduction — which is actually the best goal for hearts and arteries.  Exercise combined with a low-carbohydrate diet that ignores fat content sheds weight the fastest and makes people healthier more quickly:

Low-carbohydrate diets that require patients to fill up on fats won’t lead to harder arteries, researchers say — at least not in the short-term.

Those who lost 10 pounds after curbing their carb intake had no differences in arterial stiffness than those on a more traditional, low-fat diet, Dr. Kerry Stewart of Johns Hopkins and colleagues reported at the American College of Sports Medicine meeting in Denver. …

Some researchers have raised concerns that replacing carbs with fats may have adverse effects on blood vessels, especially since promoting consumption of fats runs “counter to what the public has been told [about reducing fat intake] for the last 20 or so years,” Stewart said.

Yet studies have shown that a low-carb diet can have positive effects on blood pressure, cholesterol, and other parameters that may reduce the risk of the artery disease atherosclerosis and subsequent heart disease.

This doesn’t mean that those who are overweight can start stuffing themselves on heavy fats with abandon, of course.  It does mean that the thrust of medical advice and in some cases public policy may be misguided, though.  For instance, the new data strongly suggests that the bans on trans-fats in New York City and Los Angeles restaurants are much less meaningful in terms of public health than their nanny-state backers claim.

How much less meaningful?  ABC News offers this example from another study:

In a companion study, 66 patients had no changes in endothelial function after eating a 900-calorie, 50-grams-of-fat meal from McDonald’s. In fact, arterial stiffness significantly improved by 16 percent after that feast, the researchers found.

“It really seemed to make the arteries relax more, but we’re not entirely sure how,” Stewart said. “We’ll have to look more deeply into that.”

The best way to control weight is to eat less and exercise more, and the best targets for reduction in diet are carbohydrates.  Low-carb diets use more meats (and vegetables and fruits), which means a higher intake of fat, but exercise and careful selection of meat can balance that effect.  Many of us have already come to that conclusion through trial and error anyway, but the new study shows that higher consumption of meat doesn’t hurt vascular health — and that tilting towards protein rather than carbs gives people a faster path to overall health.

The McDonald’s test shows us just how much we have to learn about the connections between diet and health in the short term, let alone the long term.  That’s why it’s a bad idea to put current assumptions into fixed public policy.  Let the scientists continue to look more deeply into those connections, and let the individual make the choices of what to eat and when.