I recall seeing the food pyramid as a child. It told us what we should eat plenty of and what we should avoid. The guidelines suggested division of food into proteins, fats and carbohydrates. It also suggested that we avoid fats and compensate by eating proteins and carbohydrates. It would be reasonable to presume that it was based on decades of study if not more. However, it was only 1980 when the first dietary guideline was published in the United States. As is common with information, once public, it seems to have been around forever.
Controversy to these guidelines is not new. Dieticians and medical experts have questioned the basis and rational of these guidelines. Recently, journalist Nina Teicholz has been more successful than others. Author of the Big Fat Surprise she challenged the bias toward carbohydrates and away from fat. In an article in September 2015, she raised doubts on both the rational and the legitimacy of the council that created the guidelines. Her objections included the fact that a large part of the research was outsourced to industry. Also, the guidelines suggested eating a low carbohydrate diet was harmful. She provided several research reports to the contrary. Finally, the members of the council were not required to reveal potential conflict of interest. Her objections were reviewed. Experts could not find anything objectionable about her arguments.
Health metrics in the United States have shown continual decline. Over 65% of Americans are overweight and 50% have Type 2 diabetes. Data for India and other countries show similar upward trends. Clearly we are doing something wrong. In the face of medical or expert advise it is hard to do otherwise. Perhaps we could start by not taking what ever is published as necessarily true.