The pendulum, it seems, has swung again.

Research released in December again cautions against the use of high-fat low-carb diets.

The European study using obese, pre-diabetic adults found the use of high-fat low-carb diets as effective as low-fat high-carb diets for losing weight, a matter already established in earlier research.

Also verified by this research was that a high-fat low-carb did not increase a pre-diabetic's chances of developing diabetes. It did so by measuring how the body produces and uses glucose, key markers in determining whether or not pre-diabetes develops into full-blown diabetes.

The only significant health difference in the diets occurred when researchers compared overall arterial stiffness. In fact, the arteries of the high-fat low-carb group had stiffened to such an extent that the lead researcher, Dr. Steven Hunter of the Royal Victoria Hospital in Belfast, announced: "By advocating low-carbohydrate high-fat diets as a weapon against obesity and diabetes, health professionals could be contributing to a dangerous rise in cardiovascular disease."

This pronouncement comes less than three years after a study published in the American Medical Journal seemed to establish the efficacy and safety of the high-fat low-carb diet.

That study compared the effectiveness of the Ornish diet, the Barry Sears Zone diet, the LEARN (Lifestyle, Exercise, Attitudes, Relationships and Nutrition) diet, and the Atkins diet. A total of 311 overweight women, most who were in their 40s, exercised and adhered to the principles of one of these four for a year.

The women on the Atkins diet lost the most weight, 10.4 pounds 45 percent more than those on the LEARN diet, 54 percent more than those on the Ornish diet, and 66 percent more than those on the Zone diet. But here's the kicker: the women on the Atkins diet also had lower blood pressure and improved their cholesterol profiles more than the women in the other three programs, indicators that the Atkins diet, the best known of the high-fat low-carb diets, did not adversely affect heart health.

Prior to this, most medicos felt that long-term use of high-fat low-carb diets increased the chances of cardiovascular problems despite research to the contrary done at the University of Duke and published in November of 2002. That's because the research was funded by the Robert C. Atkins Foundation.

This research found that the Atkins diet allowed the overweight to lose weight at a higher rate than the standard American Heart Association's diet and that cardiovascular health wasn't compromised the proof being that after six months, those in the study on the Atkins diet had a greater reduction in triglycerides, a bigger shift from the smaller, more dangerous LDL particles to the larger, not so dangerous ones, and 7 percent more of the "good" cholesterol, the HDLs than those on the AHA's diet.

So the question for today is: How can a diet go from unhealthy to healthy to unhealthy again in less than a single decade?

You, surprisingly enough, may have the answer. But it's not necessarily in the back of your mind or on the tip of your tongue.

It's built into your genes.

I have argued since the 1980s that the optimal diet for an individual is as unique as a snowflake, and emerging research suggests that sentiment is spot on. This thought first crossed my mind when I tried to understand how the Ornish diet could reverse heart disease in some subjects, yet didn't even improve blood cholesterol levels in others.

Now, ongoing work with genomes has led Victoria Shanta Retelny, R.D., L.D.N, in the December issue of Environmental Nutrition to state that, because of the differences in our genes, "[even] if every human ate and drank the same foods every day, there would still be a variety of health outcomes."

For proof, Retelny cites the current situation with the omega-3s. The fact that some studies find consuming more of this reduces the incidence of some serious diseases, like cancer and cardiovascular disease, and others do not has been explained in a review of 89 omega-3 studies.

The review, published last March in the Journal of the American Dietetic Association, brought to light that some people have a genetic variation that allows omega-3 to work effectively in the body, but others do not, something not considered in the formulation of the 89 studies.

Similar gene-based explanations for contradictory research pronouncements have been offered for a whole host of promising supplements, including one I swear by, epigallacatechin-3-gallate (EGCG), the key compound in green tea. In fact, I have written that I felt that I had stopped colds and sore throats on numerous occasions simply by drinking six to eight cups throughout the day.

So what the latest research suggests is not that drinking green tea or following a high-fat low-carb diet will or will not work for you, but that it's a matter of genetic makeup. While that may be frustrating for some, it is liberating for others, for it means that solutions are out there.

It's just that it's your job and not the job of some researcher somewhere to find them.