High-carb diets may increase more than just waistlines. New research suggests they might raise the risk of breast cancer.

Women in Mexico who ate a lot of carbohydrates were more than twice as likely to get breast cancer than those who ate less starch and sugar, scientists found.

The study is hardly the last word on the subject, but it is one of the few to examine how the popular but controversial low-carb diet craze might affect the odds of getting cancer, as opposed to its effects on cholesterol and heart disease.

The new findings also don’t mean that it is safe or healthful to eat lots of meat, cheese or fats, as many people who go on low-carb diets do, experts say.

“There are many concerns with eating diets high in animal fat,” said Dr. Walter Willett, chief of nutrition at the Harvard School of Public Health. “If people do want to cut back on carbohydrates, it’s really important to do it in a way that emphasizes healthy fats, like salads with salad dressings.”

Willett worked on the study with doctors at Instituto Nacional de Salud Publica in Cuernavaca, Mexico. It was funded by the U.S. Centers for Disease Control and Prevention, the Ministry of Health of Mexico, and the American Institute for Cancer Research. Results were published today in the journal Cancer Epidemiology, Biomarkers & Prevention.

Fats, fiber and specific foods have long been studied for their effects on various types of cancer, but few firm links have emerged. Being overweight is known to raise risk, but the new study took that into account and still found greater risk from high carbohydrate consumption.

Scientists think carbs may increase cancer risk by rapidly raising sugar in the blood, which prompts a surge of insulin to be secreted. This causes cells to divide and leads to higher levels of estrogen in the blood, both of which can encourage cancer.

A study earlier this year suggested that high-carb diets modestly raised the risk of colon cancer. Little research has been done on their effect on breast cancer, and results have been mixed. One study last year found greater risk among young women who ate a lot of sweets.