Obesity is a serious problem of increasing prevalence, closely associated with several serious chronic diseases which diminish lifespan and strain health services.
Furthermore, dietary management advice for weight reduction is coming from various sources and is often unclear and sometimes contradictory. For example, is fat or carbohydrate, or total calorie intake reduction, more important for weight loss?
The earliest and most famous reports of a low-carbohydrate diet for weight loss was a 1863 pamphlet by William Banting, a retired London undertaker entitled, Letter on Corpulence, Addressed to the Public, selling 63,000 copies in Britain alone.
Aged sixty-six, only five feet five inches tall and weighing more than 200 pounds, Banting was in poor health. Doctors had advised him to exercise and reduce calories. He took to rowing daily for two hours but found that exercise only increased his appetite and cutting calories left him exhausted.
In 1862, Banting consulted London surgeon William Harvey who put him on a low-carbohydrate diet. Harvey knew that farmers sometimes fattened livestock on sugary, starchy diets, and he also guessed a possible link between obesity and diabetes, because French physicians treated diabetes with a carbohydrate-free diet.
He advised Banting to eat three meals a day of meat, fish or poultry and game, and to avoid foods containing sugar and starch, in particular bread, rice, milk products (because of the sugar lactose), beer, sweets and root vegetables, especially potato.
In a year, Banting lost 46 pounds and claimed to feel marvellous, all his physical ailments having disappeared.
The fourth edition of his book, in 1869, reported he had lost 50 pounds and regarded his general health “extraordinary”. He lived to the age of eighty-one, well beyond the average life expectancy for men in England at the time.
Versions of Banting’s diet were adopted by European doctors to treat their patients. In the US, Sir William Osler, famous 19th century physician and one of the founders of John Hopkins Hospital, promoted a variation of the diet in his seminal 1892 medical textbook.
In 1919, Blake Donaldson, a New York physician, stumbled on the diet independently. He was frustrated by his inability to help obese patients lose weight simply by reducing calories. At Manhattan’s Natural History Museum he discovered that Eskimos lived mostly disease-free on a diet of fatty seal meat.
When carbohydrates are eaten frequently, insulin encourages more blood sugar to be stored as tissue fat and hence weight gain
Donaldson decided to give it a try, prescribing fatty meat three times a day. In his 1961 memoir, Strong Medicine, he insists that over 40 years, some 17,000 patients did remarkably well on this regime, losing two to three pounds a week without feeling hungry. The important point, he stressed, was that unlike other “anti-obesity treatments”, such as calorie restriction, his patients were able to keep the weight off.
In 1944, another New York doctor, Alfred Pennington, heard Donaldson give a talk about the low-carbohydrate diet. He also discovered German and Austrian 1920s and 1930s research which had pinpointed hormones as the driver of obesity.
This new hypothesis of how people got fat (which had nothing to do with overeating or under-exercising) concluded that obesity was a disorder of metabolism and that the pancreatic hormone insulin was responsible for fat deposition.
It had been argued incorrectly (unfortunately even by dieticians today) that because fat contains more calories per gram than either protein or carbohydrate, dietary fat must make people fat.
Whenever carbohydrates are eaten, blood sugar is produced and, if it’s not used by muscles during exercise, the pancreas secretes insulin to store it as tissue fat. When carbohydrates are not eaten, normal blood sugar level is maintained by breakdown of tissue fat, resulting in weight loss.
When carbohydrates are eaten frequently, insulin encourages more blood sugar to be stored as tissue fat and hence weight gain. Dietary fat does not stimulate insulin secretion.
In the 1990s the low-carbohydrate diet was “rediscovered” and popularised by Robert Atkins, a New York cardiologist. The nutrition mainstream however remained reluctant to recommend it to the entire American population because it had not been subjected to a long-term clinical trial.
By the late 2000s, the longest trial had lasted only one year. This was the ‘A to Z’ study at Stanford University, which showed that premenopausal women on the Atkins diet (high fat / low carbohydrate) had better outcomes in every way, compared to women on Barry Sears’s Zone diet (moderately low carbohydrate), the LEARN diet (moderately low fat, moderately high carbohydrate), and the Ornish diet (very low fat and very high carbohydrates).
Furthermore, in 2008, results of a two-year well-controlled Israeli study on 322 overweight men and women were published. Subjects were divided into three groups, one eating a low-fat diet, another a Mediterranean diet, and a third the Atkins diet. For every marker of heart disease measured, Atkins dieters looked the healthiest and lost most weight.
A Maltese National Food Consumption Survey, reported to cost around €200,000 (Times of Malta, April 17), aims to reveal the dietary cause of Maltese obesity figures. This survey may unfortunately end up rediscovering the wheel.
Albert Cilia-Vincenti is a pathologist. He is also chairman of the Academy of Nutritional Medicine (London) and a former scientific delegate to the European Medicines Agency.