America is caught in the middle of an “informational cascade” where subsequent scientists build new premises on the claims of previous researchers. If the first scientists in the line of research got it right, then … well, there’s nothing really to discuss. But if the initial findings were flawed, every theory built on that conclusion is also kaput. Welcome to obesity research.
Yesterday, New York Times science reporter John Tierney outlined this "cascade" phenomenon as it relates to “expert” diet recommendations: 

The notion that fatty foods shorten your life began as a hypothesis based on dubious assumptions and data; when scientists tried to confirm it they failed repeatedly. The evidence against Häagen-Dazs was nothing like the evidence against Marlboros.

Tierney sought out “the most rigorous meta-analysis of the clinical trials of low-fat diets” and discovered that it found no significant impact on mortality. More recent research has also broken away from the group-think. A study in the prestigious Lancet medical journal found that people with low BMIs, not the overweight or obese, had the highest risk of heart disease and early death. But the media didn’t widely cover these findings that contradicted the party line.
Instead, the report covered by multiple news outlets found that Cuba’s economic downturn had led to a substantial drop in average calories eaten (aka “famine”) and a decrease in obesity rates (aka “starvation”). The researchers recommend that the U.S. look to Cuba’s "successful" experience as a dietary standard. (Never mind that premature death rates among the elderly actually inched upward and there was an epidemic of degenerative nerve damage as a result of widespread malnutrition.) 
These reduced-fat, low-salt, no-food recommendations — besides being unjustified — may well have unintended consequences as severe as those observed in the Cuba study. If Americans hope to avoid the lemmings’ fate, they should tune out the latest nutrition survey and fad diets. Rather, heed the advice of Dr. Edward H. Ahrens Jr., a distinguished researcher who spoke out against the erroneous 1970s Congressional report that advised Americans to eat less fat:

This is a matter … of such enormous social, economic and medical importance that it must be evaluated with our eyes completely open. Thus I would hate to see this issue settled by anything that smacks of a Gallup poll.