According to University of Virginia professor Glenn Gaesser, eating sandwiches with white bread, or an occasional doughnut, isn't going to kill you, or necessarily even lead to obesity.
He analysed dozens of studies about the eating habits and health of hundreds of thousands of men and women, and failed to find that those who ate lots of carbohydrate were heavier.
Gaesser found that diets high in carbohydrates are almost universally associated with slimmer bodies. More importantly, he discovered that consuming lots of high-glycemic foods is not associated with higher body weights.
"I found, totally contrary to current nutritional thinking, carbohydrates are not fattening. In fact, just the opposite. There is no reason to be eating fewer carbs - they're not the enemy," the Daily Mail quoted him, as saying.
He added that cutting back on carbs often led to eating more fatty foods, leading to weight gain.
Gaesser further said that carbohydrates play a vital role in a balanced diet, providing fibre, vitamins, minerals and antioxidants.
He urged dieters to count calories, not carbs, and explained that the key to weight loss was to eat fibre-rich foods, exercise regularly and eat reduced fat dairy products and lean meat.
However, Gaesser's findings were questioned by British nutritionist Patrick Holford, who insisted that animal studies had shown that high-carbohydrate diets "convert rapidly into fat".
"The old idea was that the way to lose weight was to eat less calories, which is what Gaesser is advocating. Gaesser is supporting what has been done for the last 20 years and clearly it's not working," Holford said.
"The human body is much more complicated and blood sugar is much more important," he added.
The study is published in the Journal of the American Dietetic Association.