Dieting just two days a week, with a low-carbohydrate focus, leads to more weight loss. And because it reduces blood levels of insulin, it may reduce the risk of cancer, as well, according to research from the United Kingdom released Thursday.
Researchers at the Genesis Prevention Center at University Hospital in South Manchester, England, said restricting carbohydrates twice weekly may be better than consistent calorie-limited dieting, in terms of preventing breast cancer and other diseases. Insulin is a hormone that promotes cancer and reducing its level in the blood may reduce cancer risk.
But they noted that more study needs to be conducted.
This year, BreastCancer.org says about 230,000 women were diagnosed with invasive breast cancer, along with nearly 58,000 noninvasive cases. More than 2,000 men were diagnosed, as well. Women have a 1 in 8 chance of a diagnosis of breast cancer, while men have a 1 in 1,000 lifetime risk.
The study findings were to be discussed at the San Antonio Breast Cancer Symposium this week.
The researchers, led by Michelle Harvie, a research dietitian at the center, studied three diets for four months to see how they impacted weight loss and also the blood markers of breast cancer risk among 115 women who had a family history of the disease. Patients were randomly assigned to a calorie-restricted, low-carbohydrate diet for two days a week, an "ad lib" low-carbohydrate diet in which subjects could eat whatever they wanted in terms of protein and healthy fats like olives and lean meats for two days a week and a standard, calorie-restricted Mediterranean diet every day. Besides dropping carbohydrates, for those two days the subjects were restricted to about 650 calories.
Both intermittent low-carbohydrate diets were better than the standard Mediterranean diet for dropping body fat, weight and insulin resistance, the researchers said. On intermittent diets the women lost about nine pounds compared to five on the standard diet. As for insulin resistance, it was reduced by 22 percent with the low-carbohydrate diets, 14 percent with the "ad lib" diet and 4 percent with the standard Mediterranean.
"It is interesting that the diet that only restricts carbohydrates but allows proteins and fats is as effective as the calorie-restricted low-carbohydrate diet," Harvie said.
A year ago, the United Kingdom researchers published similar findings in the International Journal of Obesity. In it, they noted the difficulty of getting people to adhere to a stringent, consistent diet. Their work found that the intermittent diet offered comparable results in terms of weight loss and reduced disease risk. Harvie led that six-month study, which was a joint venture funded by Breast Cancer Campaign and the World Cancer Research Fund.
Harvie told MSNBC that those following the diet in the research could, on those two low-carb days, "skip bread, pasta, root vegetables like potatoes, carrots and parsnips to get to the 50-gram limit. The diet allows for one piece of fruit on the low carb days. Other foods on the menu include nuts and green, leafy vegetables, peppers, mushrooms, tomatoes, broccoli, eggplant and cauliflower."
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