We are too heavy -- and I don’t mean overweight.

You see, we’re heavy with metals, not fat. Nearly 40 percent of us have toxic levels of lead in our bodies. And we don’t even know it.

That doesn’t mean we don’t have symptoms.

You may have headaches, insomnia, irritability, a low sex drive, or tremors.

You may have mood problems, nausea, depression, memory difficulties, trouble concentrating, poor coordination, or even constipation.

Yet most of us attribute these symptoms to other problems. We don’t recognize that they may be caused by lead poisoning.

I just returned from a medical conference on heavy metals and health. Although I have been treating toxicity from heavy metals for more than a decade (including in myself) I was surprised to hear about new research that has been completely ignored by the media.

A study published in 2006 in the conservative medical journal Circulation, for example, should have been on the front page of the New York Times.

Let me tell you about why the study was so important -- and why you probably won’t hear about it from your doctor.

Is being heavy in your genes?

Not so fast.

Obesity genes account for only 5 percent of all weight problems.

But what about the other 95 percent of weight problems?

And why are we seeing such an epidemic of obesity in America today? It is the single most important public health issue facing us.

If genes do not account for obesity, is our high-fat diet to blame?

Wrong again!

But fat contains 9 calories per gram, so shouldn’t eating more fat (and more calories) make you gain weight?

Nothing could be further from the truth.

In fact, pioneering research by Harvard Medical School’s David Ludwig shows us the real reason that low-fat diets do not work -- and reveals the true cause of obesity for most Americans.

He correctly points out that careful review of all the studies on dietary fat and body fat -- such as those done by Dr. Walter Willett of the Harvard School of Public Health -- have shown that dietary fat is not a major determinant of body fat.

Let me repeat that.

==> Dietary fat is not a major determinant of body fat.

Should we buy food with health claims on the label?

These days, we are seeing more and more health claims that go beyond the usual. These include “trans fat-free,” “gluten-free,” “heart healthy,” and foods spiked with vitamins, such as my new favorite: Diet Coke Plus, with vitamins and minerals.

We see whole-grain Pop Tarts and Tyson chicken with misleading labels such as “raised without antibiotics.” We see natural sweeteners called Sweet Fiber. We see whole-grain Cheerios that are still full of sugar.

Now you can get “health food” like salads at McDonald’s, but with salad dressings that have more calories than a Big Mac.

And we also see antioxidant-spiked junk food and ginkgo-spiked energy drinks.

What should we make of all these marketing claims? Do they provide any benefit?