Berit Johansen, a professor of biology at Norwegian University of Science and Technology, Ingerid Arbo and Hans-Richard Brattbakk fed slightly overweight people different diets and studied the effect of the diet on gene expression.
Gene expression describes the process in which information from a gene's DNA sequence is translated into a substance, like a protein, that is used in a cell's structure or function.
"We have found that a diet with 65 percent carbohydrates, which often is what the average Norwegian eats in some meals, causes a number of classes of genes to work overtime," Johansen said in a statement. "This affects not only the genes that cause inflammation in the body, which was what we originally wanted to study, but also genes associated with development of cardiovascular disease, some cancers, dementia, and type 2 diabetes -- all the major lifestyle-related diseases."
Each study participant was able to be his or her own control person -- each was allowed to go on both diets, with a one-week break in between the diets. Half began with one diet, while the rest started with the other.
One diet had 65 percent of calories from carbohydrates, 15 percent from protein and 20 percent from fat, the second diet was half carbs with twice as much protein and fat as in the first diet, the researchers said.
"Both low-carb and high-carb diets are wrong," Johansen said. "But a low-carb diet is closer to the right diet. A healthy diet shouldn't be made up of more than one-third carbohydrates -- up to 40 percent of calories -- in each meal, otherwise we stimulate our genes to initiate the activity that creates inflammation in the body."