THE CARBOHYDRATE-INSULIN HYPOTHESIS
AS WE’VE NOW established that insulin causes obesity, our next question is: What foods causes our insulin levels to rise or to spike? The most obvious candidate is the refined carbohydrate—highly refined grains and sugars. This brings us not to a new idea, but back to a very old idea that predates even William Banting: the idea that “fattening carbohydrates” caused obesity.
Highly refined carbohydrates are the most notorious foods for raising blood sugars. High blood sugars lead to high insulin levels. High insulin levels lead to weight gain and obesity. This chain of causes and effects has become known as the carbohydrate-insulin hypothesis. The man who found himself at the center of the controversy was the infamous Dr. Robert Atkins.
In 1963, Dr. Robert Atkins was a fat man. Like William Banting 100 years before, he needed to do something. Weighing in at 224 pounds (100 kilograms), he had recently begun his cardiology practice in New York City. He had tried the conventional ways to lose weight, but had met with no success. Recalling the medical literature published by Drs. Pennington and Gordon on low-carbohydrate diets, he decided to try the low-carbohydrate approach himself. To his amazement, it worked as advertised. Without counting calories, he shed his bothersome extra weight. He started prescribing the low-carbohydrate diet to patients and had some notable success.
In 1965, he appeared on the Tonight Show, and in 1970, was featured in Vogue. In 1972, he published his original book, Dr. Atkins’ Diet Revolution. It was an immediate bestseller and one of the fastest-selling diet books in history.
THE LOW-CARB REVOLUTION
DR. ATKINS NEVER claimed to have invented the low-carb diet. That approach had been around long before the formerly popular diet doctor wrote about it. Jean Anthelme Brillat-Savarin wrote about carbohydrates and obesity in 1825. William Banting described the same relationship in his bestselling pamphlet, Letter on Corpulence, in 1863. These ideas have endured for close to two centuries.
However, by the mid 1950s, the caloric-reduction theory of obesity was gaining ascendency. It seemed so much more scientific to be discussing calories rather than foods. But there were still holdouts. Dr. Alfred Pennington wrote an editorial in the New England Journal of Medicine in 1953 emphasizing the role of carbohydrates in obesity.1 Studies by Dr. Walter Bloom comparing low-carbohydrate diets to fasting regimens had found comparable weight loss between the two.2
Dr. Irwin Stillman wrote The Doctor’s Quick Weight Loss Diet in 1967, recommending a high-protein, low-carbohydrate diet.3 It quickly sold more than 2.5 million copies. Since it takes extra energy to metabolize dietary protein (the thermogenic effect of food), eating more protein could theoretically cause more weight loss. Dr. Stillman himself lost fifty pounds following the “Stillman diet,” which contained up to 90 percent protein. He reportedly used the diet to treat more than 10,000 overweight patients. By the time Dr. Atkins joined the fray, the low-carbohydrate revolution was already well underway.
Dr. Atkins argued in his 1972 bestseller that severely restricting carbohydrates would keep insulin levels low, thus reducing hunger and eventually leading to weight loss. It didn’t take long for the nutritional authorities to respond. In 1973, the American Medical Association’s Council on Foods and Nutrition published a blistering attack on Atkins’s ideas. Most physicians at that time worried that the high fat content of the diet would lead to heart attacks and strokes.4
Nonetheless, low-carb proponents continued to preach. In 1983, Dr. Richard Bernstein, himself a type 1 diabetic since age nine, opened a controversial clinic to treat diabetics with a strict low-carbohydrate diet—a method that directly contradicted most nutritional and medical teachings of the time. In 1997, Bernstein published Dr. Bernstein’s Diabetes Solution. In 1992 and then again in 1999, Atkins updated his bestseller with the publication of Dr. Atkins’ New Diet Revolution. Bernstein’s and Atkins’s books would become monster bestsellers, with more than 10 million copies sold. In 1993, scientists Rachael and Richard Heller wrote The Carbohydrate Addict’s Diet, which sold more than 6 million copies. The Atkins onslaught had well and truly begun.
The low-carb diet’s popularity, rekindled in the 1990s, ignited into a full- scale inferno in 2002 when award-winning journalist Gary Taubes wrote a controversial lead article in the New York Times entitled “What If It’s All Been a Big Fat Lie?” He argued that dietary fat, long believed to cause atherosclerosis, was actually quite harmless to human health. He followed that up with the best-selling books Good Calories, Bad Calories and Why We Get Fat, in which he expounded on the idea that carbohydrates were the root cause of weight gain.
THE EMPIRE STRIKES BACK
THESE IDEAS WERE slow to take hold in the medical community. Many physicians still felt that low-carb was simply the latest in a long line of failed dietary fads. The American Heart Association (AHA) published its own book called the No-Fad Diet: A Personal Plan for Healthy Weight Loss. It’s only mildly ironic that while condemning other diets, the AHA would recommend the only diet (low-fat) repeatedly proven to fail. But the low-fat religion was enshrined in the medical community and it did not tolerate disbelievers. Despite a stunning lack of evidence to support this low-fat advice, medical associations such as the AHA and the American Medical Association were quick to defend their beliefs and denounce these new “fad” diets. But the Atkins onslaught was relentless. In 2004, more than 26 million Americans claimed to be on some type of low-carbohydrate diet. Even fast-food chains introduced low-carb lettuce-wrapped burgers. The possibility of permanently reducing excess weight and all its associated health complications seemed within grasp.
The AHA admitted that the reduced-fat diet was unproven over the long term. It also conceded that the Atkins diet evidenced a superior cholesterol profile and yielded a more rapid initial weight loss. Despite these benefits, the AHA maintained its concerns with atherogenicity—the rate at which plaques would form in the arteries. There was, of course, no evidence to support this concern. Regarding its own recommended but scientifically unsupported low-fat diet, the AHA had no concerns at all!
No concern that higher intake of sugar and other refined carbohydrates could be harmful. No concern that the low-fat diet had been proved a spectacular failure by every dietary study done. No concern that the obesity and diabetes epidemics were raging full force under their very noses. The AHA fiddled while Rome burned.
During the forty years that the AHA advised a low-fat diet, the obesity crisis grew to gargantuan proportions. Yet at no time did the AHA question whether their completely ineffectual advice was actually helping people. Instead, doctors played their favorite game: blame the patient. It is not our fault the diet doesn’t work. It is their fault for not following the diet.
LOW-CARB DIETS: A STUNNED MEDICAL COMMUNITY
AS THE NEW competitor challenged conventional dietary wisdom, the campaign of slurs and innuendo began. Nonetheless, new studies started appearing by the mid 2000s comparing the “new” low-carb diets to the old standards. The results would shock many, myself included. The first study, published in the prestigious New England Journal of Medicine in 2003,5 confirmed greater short-term weight loss with the Atkins diet. In 2007, the Journal of the American Medical Association published a more detailed study.6 Four different popular weight plans were compared in a head-to-head trial. One clear winner emerged—the Atkins diet. The other three diets (Ornish, which has very low fat; the Zone, which balances protein, carbohydrates and fat in a 30:40:30 ratio; and a standard low-fat diet) were fairly similar with regard to weight loss. However, in comparing the Atkins to the Ornish, it became clear that not only was weight loss better, but so was the entire metabolic profile. Blood pressure, cholesterol and blood sugars all improved to a greater extent on Dr. Atkins’s diet. In 2008, the DIRECT (Dietary Intervention Randomized Controlled Trial) study7 reaffirmed once again the superior short-term weight reduction of the Atkins diet. Done in Israel, it compared the Mediterranean, the low-fat and the Atkins diets. While the Mediterranean diet held its own against the powerful, fat-reducing Atkins diet, the low-fat AHA standard was left choking in the dust—sad, tired and unloved, except by academic physicians. More importantly, the metabolic benefits of both the Atkins and Mediterranean diets were confirmed. The Atkins diet reduced average blood sugar levels by 0.9 percent, far more than the other diets and almost as powerful as most medications.
The high-protein, low-glycemic index diet maintained weight loss better than the low-fat diet over six months.8 Part of the reason may be that different weight-loss diets provoke different changes in total energy expenditure. Dr. David Ludwig from Harvard University9 found that the low- fat diet slowed body metabolism the most. What was the best diet for maintaining metabolism? The very-low-carbohydrate diet. This diet also seemed to reduce appetite. Dr. G. Boden wrote in the Annals of Internal Medicine in 2005, “When we took away the carbohydrates, the patients spontaneously reduced their daily energy consumption by 1,000 calories a day.”10 Insulin levels dropped and insulin sensitivity was restored.
Perhaps eating refined carbohydrates leads to “food addictions.” Natural satiety signals are hormones that are extremely powerful deterrents to overeating. Hormones such as cholecystokinin and peptide YY respond to ingested proteins and fats to signal us to stop eating. Now, let’s return to that all-you-can-eat buffet mentioned in chapter 5.