FRANCE'S most popular weight-loss regimes, including the number one Dukan diet, are ineffective and potentially dangerous to people's health, doctors have warned. The Agence Nationale de Sécurité Sanitaire has issued a warning over 14 of the most fashionable diet regimes in France. Researchers at the Institut Pasteur in Lille assessed each regime, including Atkins and Montignac, for its nutritional value and potential side-effects. Head of nutritional research Jean-Michel Lecerf, who led the study, said the diets disrupted the body's natural metabolism and led to serious nutritional imbalances.
In nearly all the diets, the protein content was typically much higher than the recommended daily intake, especially the Dukan diet, which is France's top-seller. Some of the diets contained 10 times less fibre than the recommended level and up to twice as much salt. They also lacked vital vitamins and minerals. The study also pointed to an increased risk of fractures and other bone problems, muscle wastage and cardiovascular problems in some of the regimes.
Dr Lecerf said that in 95 per cent of cases, people who follow a dietary regime regain weight as soon as they finish. In some instances, the weight they regain is greater than the amount lost. He said: “Each regime is less effective than the one before, and the weight gain afterwards is greater each time.” According to the study, about 70 per cent of people in France have followed some sort of weight-loss programme, many without consulting a doctor beforehand.
The Régime Dukan is the most popular diet in France at the moment. Like Atkins, it is high in protein in the initial “attack” phase, but low in fat. Next comes the “cruise” phase, with protein-only days and protein-and-veg days. Potatoes are banned, as are high-calorie vegetables such as peas, carrots and sweetcorn.
More than two million copies of the Dukan book Je ne sais pas maigrir have been sold in France.
Experts have suggested that an intensive lifestyle intervention helps individuals with type 2 diabetes lose weight and keep it off, along with improving fitness, control of blood glucose levels and risk factors for cardiovascular disease. Improving blood glucose control and cardiovascular risk factors in patients with type 2 diabetes is critical in preventing long-term complications of the disease.
The Look AHEAD (Action for Health in Diabetes) Research Group conducted a multicenter randomized clinical trial comparing the effects of an intensive lifestyle intervention to diabetes support and education among 5,145 overweight individuals with type 2 diabetes.
Of these, 2,570 were assigned to the lifestyle intervention, a combination of diet modification and physical activity designed to induce a 7 percent weight loss in the first year and maintain it in subsequent years. The 2,575 individuals assigned to the diabetes support and education group were invited to three group sessions each year. On average, across the four-year period, individuals in the lifestyle intervention group lost a significantly larger percentage of their weight than did those in the diabetes support group.
They also experienced greater improvements in fitness, hemoglobin A1c level (a measure of blood glucose), blood pressure and levels of high-density lipoprotein. Individuals in the diabetes support group, on the other hand, experienced greater reductions in low-density lipoprotein, owing to greater use of cholesterol-lowering medications in this group.
The report was published in the September 27 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
To determine whether intermittent hypoxia (IH) and chronic hypoxia (CH) would have different metabolic effects, Dr. Lee and colleagues fitted adult male mice with arterial and venous catheters for continuous rapid blood monitoring of glucose and insulin sensitivity.
They then exposed the mice to either seven hours of IH, in which treatment, oxygen levels oscillated, reaching a low of about 5 percent once a minute, or CH, in which they were exposed to oxygen at a constant rate of 10 percent, and compared each treatment group to protocol-matched controls.
When compared to the control group, the IH mice demonstrated impaired glucose tolerance and reduced insulin sensitivity; the CH group, however, showed only a reduction in glucose tolerance but not insulin sensitivity compared to controls. “Both intermittent hypoxia and continuous hypoxia exposed mice exhibited impaired glucose tolerance, but only the intermittent hypoxia exposed animals demonstrated a reduction in insulin sensitivity,” said Euhan John Lee, M.D., a fellow at the Medical Center.
“The intermittent hypoxia of sleep apnea and the continuous hypoxia of altitude are conditions of hypoxic stress that are known to modulate glucose and insulin homeostasis. Although both forms of hypoxia worsen glucose tolerance, this research demonstrated that the increase in insulin resistance that accompanies intermittent hypoxia, or sleep apnea, is greater than that seen with continuous hypoxia, or altitude,” explained Dr. Lee.
The specific finding that intermittent, but not continuous, hypoxia induced insulin resistance was not expected.
Increased generation of reactive oxygen species, initiation of pro-inflammatory pathways, elevated sympathetic activity, or upregulation of insulin counter-regulatory hormones in IH may contribute to the greater development of insulin resistance in those mice versus those exposed to continuous hypoxia.
“As sleep apnea continues to rise with the rate of obesity, it will be increasingly important to understand both the independent and interactive effects of both morbidities on the development of metabolic disorders. This research demonstrated that intermittent hypoxic exposure can cause changes in insulin sensitivity and insulin secretion, which may have important consequences in metabolically vulnerable diabetic patients who present with co-morbid sleep apnea,” said Dr. Lee. (ANI)