Study: Cutting Carbs Two Days a Week Is Better than Full-Time Dieting

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Good news for dieters who feel that counting calories has become a full-time job. According to new research, you might do better to cut carbs just two days a week instead of going low cal every day.

In a recent study, presented at the San Antonio Breast Cancer Symposium, British researchers found that women who eliminated carbohydrate-rich foods like bread, pasta, potatoes and rice two days a week and ate their normal diet the rest of the time lost an average of 9 lb. over four months. Meanwhile, women in a similar group who ate a 1,500-cal.-per-day Mediterranean-style diet for the same time period lost only 5 lb.

Women on the intermittent diet not only lost more weight but also showed greater improvements on other markers of health, including levels of insulin and leptin.

The study was borne of the researchers’ efforts to come up with a diet that people could actually stick with, especially women who are at high risk of breast cancer. Obesity is a known risk factor for the disease, and hormones like insulin and leptin are also associated with tumor development.

“Weight loss and reduced insulin levels are required for breast-cancer prevention, but [these levels] are difficult to achieve and maintain with conventional dietary approaches,” lead author Michelle Harvie, a research dietitian at the Genesis Prevention Center at the University Hospital in South Manchester, England, said in a statement.

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All 115 women who participated in the study were at high risk of breast cancer based on their family histories of the disease. They were randomly assigned to one of three diets: a two-day-a-week low-carb diet that restricted calories to 650 on the carb-free days; a similar low-carb diet, except with no calorie restriction (participants were allowed to load up on protein and healthy fats, such as lean meats, olives and nuts, on no-carb days); or a standard 1,500-calorie-a-day Mediterranean-style diet seven days a week.

Both intermittently dieting groups lost more weight and saw more improvements in insulin resistance, compared with the Mediterranean-style diet group. The group that ate the calorie-restricted, low-carb diet fared a little better when it came to insulin levels, however, reducing insulin resistance by 22%, compared with 14% for the unrestricted low-carb dieters and 4% for those on the Mediterranean diet.

The researchers said the results were compelling enough to warrant further study on the relationship between carbohydrate consumption and breast cancer.

Meredith Melnick is a reporter at TIME. Find her on Twitter at @MeredithCM. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.

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