Low carbohydrate diets go in and out of fashion for weight loss, but a new piece of research suggests that an occasional low carb day is better than traditional diets for helping to prevent breast cancer. The findings are set to be presented at the San Antonio Breast Cancer Symposium, where the researchers describe a diet that may lower insulin and prevent cancer better than a traditional diet.

Reducing both insulin levels and weight are known to help prevent breast cancer. The problem is that it's hard for patients to stick with dramatic dietary changes. Lead by medical researcher Michelle Harvie, the group compared three diets over a four month period for their effects on weight loss and blood markers of breast cancer risk. They gave patients either a calorie-restricted, low-carb diet for two days of the week, an "ad lib" low-carb diets where they were allowed unlimited protein and healthy fats for two days a week, or a calorie-restricted "Mediterranean diet" for seven days a week.

Both the intermittent diets produced a greater effect than the constant one, causing a mean weight loss of 4kg per person, compared to 2.4kg on the "Mediterranean diet". Insulin resistance dropped 22% with the restricted low-carbohydrate diet, 14% with the "ad lib" low-carbohydrate diet, but only 4% percent with the standard one.

So rather than trying to force yourself into a lifetime of culinary asceticism, it might be easier and more effective to just keep things strictly under control for a couple of days a week, and eat like normal the rest of the time.