Studies tended to be short term, diets unsustainable, differences between them clinically unimportant. The only thing that really seemed to help individuals with diabetes was weight loss — and for weight loss there is no magic diet.
But folks need diet guidance, Dr. Kahn reasoned, and the association really should say something about diets. So it, with the Department of Agriculture’s food pyramid, went like the National Institutes of Health.
Why? “It’s a diet for all America,” Dr. Kahn said. ”It has lots of vegetables and fruits and a decent number of fat.”
There's a diet that helps with diabetes, the two doctors said, one that confines — or according to Dr. Hallberg, severely restricts — — carbohydrates.
“If the target will be to get patients off their drugs, including insulin, and conclude rather than simply control their diabetes, essential carb limitation is undoubtedly the greatest nutrition plan,” Dr. Hallberg said in an email. “This would include removal of all processed foods, potatoes and sugars and grains. There is an ever growing and major body of literature that supports this process.”
But there aren't any large and rigorous studies showing that low carbohydrate diets offer an edge and, in fact, there is not a consensus on the definition of a low-carbohydrate diet — it can change from doctor to doctor.
“There have been discussions for literally the entire history of diabetes about which type of diet is best,” said Dr. C. Ronald Kahn, chief academic officer at Joslin, and no connection to Dr. Richard Kahn. But, he said, “the reply isn’t so straightforward.”
They stayed in a clinical center where they ate controlled diets. The researchers inquired what would occur if calories in the diet were kept constant but the carbohydrate composition of a diet varied from high to quite low. The answer was that insulin secretion dropped with the very low carbohydrate diet by 50 percent, meaning that much less insulin was needed to maintain normal blood glucose levels. “Since diabetes results when the body can’t create enough insulin, perhaps it is wise to reduce the amount of insulin it needs by eating very low carbohydrate diets,” Dr. Hall said at diabetes forums.
Some longer duration studies, though, failed to demonstrate that low carbohydrate diets benefited glucose control.
Even if diets are effective in the short term, Dr. Hall said, “the problem is adhering to the diet over the long term.”
Within an analysis of weight loss diets (not particularly for diabetics) released this summer, he and Yoni Freedhoff of the University of Ottawa wrote: “Diet adherence is so ambitious it is poor even in short-term studies where all food is provided. When diets are prescribed, adherence probably will fall over the long term despite self-reports to the contrary.”
But short term studies of merely several weeks — which constitute the majority of the diet studies — can be misleading, said Dr. C. Ronald Kahn.
“ In the short term, the carbohydrate diet that is low sometimes does better on glycemic control,” he said. “But as time advances the difference largely vanishes. What counts is which diet helps most with long term weight loss. ”
The cause the advantage that's occasionally found with a low carbohydrate diets has a tendency to vanish, Dr. C. Ronald Kahn included, is likely a mix of individuals failing to stick to the diets and their bodies correcting to them.
Another issue with low carbohydrate diets, researchers said, is the question if diabetics truly follow the diet for decades or years of what will occur to complete health. (Heart attacks are the major killer of individuals with diabetes.) Insulin levels may be better but, said Dr. Rudolph Leibel, co-manager of Columbia University’s Naomi Berrie Diabetes Center, “effects of a low carbohydrate diet on lipoproteins and vascular biology could cancel such a ‘benefit.’” Quite simply, it's not clear if a lower insulin level would translate into fewer heart attacks.