Three months after going off the diet, seven were free of diabetes.
Sound too tough to follow? Don't worry, the researchers aren't recommending the low-cal diet as a treatment for diabetes.
"We used the 600-calorie diet to test a hypothesis. What I can tell you definitively is that if people lose substantial weight by normal means, they will lose their diabetes," says study head Roy Taylor,MD, director of the Newcastle Magnetic Resonance Centre at Newcastle University in England.
The findings were published online by the journal Diabetologia and presented here at the annual meeting of the American Diabetes Association (ADA).
Nearly 26 million Americans have diabetes, about 95% of whom have type 2 diabetes. It develops when the body does not produce enough insulin and/or the insulin that is produced doesn't work properly. As a result, blood sugar levels shoot up.
After one week on the diet, participants' fasting blood sugar levels were no longer elevated, he says.
MRI scans showed that the fat levels in the pancreas fell from around 8% -- considered high -- to a normal 6%.
After eight weeks on the diet, their bodies were once again making sufficient insulin, essentially reversing their diabetes, Taylor says.
"Fat in the pancreas inhibits the action of beta cells in making insulin. The low-calorie diet got rid of this excess fat," he says.
The men and the women in the study weighed an average of 220 pounds at the start of the study and lost an average of 33 pounds over eight weeks. By three months later, they had regained an average of 6.5 pounds.
David M. Kendall, MD, chief scientific and medical officer for the ADA, tells WebMD that it's been known for a while that "substantial calorie reduction can be very effective in rapidly improving diabetic control, especially in people who are obese.
"What is unique about this study is it looked at some of the mechanisms that underlie the rapid improvement," he says.
More research is needed to determine whether the low-cal diet results in a permanent reversal of diabetes, Taylor says. "We also have to figure out a more practical way for people to get these results -- that is, to get fat out of pancreas and keep it out," he says.