At the very moment that the government started telling Americans to eat less fat, we got fatter. The truths about why we gain weight and why it is so hard to lose it just might turn out to be much different from what we have been led to think. If the members of the American medical establishment were to have a collective find-yourself-standing-naked-in-Times-Square-type nightmare, this might be it. They spend 30 years ridiculing Robert Atkins, author of the phenomenally-best-selling ‘‘Dr. Atkins’ Diet Revolution’’ and ‘‘Dr. Atkins’ New Diet Revolution,’’ accusing the Manhattan doctor of quackery and fraud, only to discover that the unrepentant Atkins was right all along. Or maybe it’s this: they find that their very own dietary recommendations—eat less fat and more carbohydrates—are the cause of the rampaging epidemic of obesity in America. Or, just possibly this: they find out both of the above are true. Puncturing the Low-Fat Myth If you haven't had a chance to read The New York Times Magazine article entitled, "What if It's All Been a Big Fat Lie?" (July 7), here are 10 key points you should know. Written by Gary Taubes, a correspondent for the journal Science, it has sparked enormous media coverage by questioning conventional wisdom about low-fat diets. 10 Key Points 1.The low-fat hypothesis has failed the test of time. Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health, is the spokesman of the longest-running and most comprehensive diet and health studies ever performed. (They include data on nearly 300,000 individuals.) Those data, says Willett, “clearly contradict the low-fat-is-good-health message ''and the idea that all fat is bad for you; the exclusive focus on adverse effects of fat may have contributed to the obesity epidemic.'' 2. Recent studies confirm the effectiveness of the Atkins approach. The results of five scientific studies recently presented at conferences are remarkably consistent. Subjects on some form of the Atkins plan lost twice as much weight as did subjects on the low-fat, low-calorie diets. In all five studies, cholesterol levels improved similarly with both diets, but triglyceride levels were considerably lower with the Atkins approach. 3.The obesity epidemic coincides with the rise of the low-fat dogma. The low-fat theory is only about 30 years old, and in that time low-fat weight-loss diets have proved in clinical trials and real life to be dismal failures. Until the late 1970s, the accepted wisdom was that fat and protein protected against overeating by making you sated, and carbohydrates made you fat. The low-fat hypothesis, not the idea of controlling carbohydrate intake, is actually the deviation from traditional thinking. 4.The low-fat dogma was politically and economically motivated. Back in the 1970’s some of the nation's best scientists disagreed with the low-fat logic, but they were effectively ignored. Once the National Institutes of Health (N.I.H.) signed off on the low-fat doctrine, the food industry quickly began producing thousands of reduced-fat food products to meet the new recommendations. Fat was replaced with sugar or high-fructose corn syrup to replace lost flavor. 5.The low-fat message is radically oversimplified, a fact few experts deny. It effectively ignores the fact that unsaturated fats, such as olive oil, are relatively good for you. As Willett explained, you will gain little to no health benefit by giving up milk, butter and cheese and eating bagels instead. 6. Endocrinology does not support low-fat diets. Endocrinology, the study of hormones, demonstrates the effect that carbohydrates have on insulin and blood sugar and in turn fat metabolism and appetite. When we eat more fat-free carbohydrates, they, in turn, make us hungrier and heavier. Put simply, a low-fat diet is not by definition a healthy diet. In practice, such a diet cannot help being high in carbohydrates, and that can lead to obesity, and perhaps even heart disease. ''For a large percentage of the population, perhaps 30 to 40 percent, low-fat diets are counterproductive,'' says Eleftheria Maratos-Flier, director of obesity research at Harvard's prestigious Joslin Diabetes Center. 7. Low-fat diets can raise triglycerides, which may prove lethal. A crucial example of how the low-fat recommendations were oversimplified is that eating a low fat, high-carbohydrate diet would, for many people, raise their triglyceride levels and lower their H.D.L. levels. This combination can lead to heart disease and Type II diabetes. 8. The link between eating fat and getting heart disease has never been demonstrated. From 1984 to the present day the N.I.H conducted five major studies and spent several hundred million dollars trying to show a connection but failed. A sixth study did conclude that reducing cholesterol by drug therapy could prevent heart disease. 9. High carbohydrate diets result in higher caloric intake. Americans are eating more calories than ever. The salient factor is the impact of carbohydrates on blood sugar and insulin. The primary role of insulin is to regulate blood-sugar levels. After you eat carbohydrates, they are broken down into sugar molecules and transported into the bloodstream. Your pancreas then secretes insulin, which shunts the blood sugar into muscles and the liver as fuel for the next few hours. This is why carbohydrates have a significant impact on insulin and fat does not. Insulin regulates fat metabolism. We cannot store body fat without it. Think of insulin as a switch. When it's on, in the few hours after eating, you burn carbohydrates for energy and store excess calories as fat. When it's off, after the insulin has been depleted, you burn fat as fuel. So when insulin levels are low, you will burn your own fat, but not when they're high. 10. Anecdotal evidence demonstrates that Atkins works. After attacking Atkins for three decades, obesity experts are now finding it difficult to ignore the copious anecdotal evidence that the program does just what is claimed. Take Dr. Albert Stunkard, a University of Pennsylvania psychiatrist, for instance. He has been trying to treat obesity for half a century, but his epiphany about Atkins and maybe about obesity as well occurred just recently when he discovered that the chief of radiology in his hospital had lost 60 pounds on the Atkins program. ''Well, apparently all the young guys in the hospital are doing it,'' he said.