In 1992, the Department of Agriculture’s proclaimed their dietary recommendations via a “food pyramid,” consisting of six horizontal sections, with carbohydrates at the bottom rung of the pyramid (thus the most important diet item), with fat and cholesterol atop the pyramid, suggesting only very sparing (< 5%) of consumption (32). The pyramid was revised in 2005 as “MyPyramid,” with the size of vertical colored sections indicating preferential food proportions. Those guidelines were again replaced in 2011, as “My Plate,” backed by First Lady Michelle Obama, showing food recommendations as sections of a plate, lacking portions for fat or meat altogether.
Starting in the late 1970s, however, a new generation of researchers, unbeholden to previous dogma, began challenging the low-fat hypothesis. For example, in 1978, an American Heart Association study was interpreted to show no association between CVD and cholesterol-containing foods (33). 1980, Bond et al. noted the difficulty in measuring atherosclerosis (34), while another study demonstrated low- (LDL) and high-density (HDL) lipoproteins as more relevant to CVD than mere total cholesterol (35). Another study claimed that total fat intake (under constant total calories) did not alter serum cholesterol(15), with others reported a lack of correlation between obesity and total fat intake, rather total calories from any food type.(36) Indeed, over the past 40 years, dietary fat consumption has declined, while obesity, and carbohydrate intake, have soared (6,37). The well-established correlation between type 2 diabetes and CVD may further implicate sugar metabolism (38).
The Adkins diet (39), or various minor variants, has experienced a revival of sorts, demonstrating statistically significant weight loss, compared to other popular low-fat diets (Ornish, LEARN, and Zone) (40,41). In the short-term (one year), high-fat diet subjects underwent greater reduction in LDL, and greater increase in HDL, compared to those on a low-fat diet. However, after two years, the high- and low-diet groups yielded very similar outcomes (42). However, other reviews have acknowledged likely benefit from low carbohydrate/high fat diets (43-46).
The anti-fat movement also led to backlash again fast-food restaurants, although most complied with the sentiment by adding “healthy” foods such as salads and fruits to their menus. One pinnacle of the low-fat movement was Martin Sperlocks’s 2004 documentary, “Super Size Me,” following a claimed 30-day diet excluded to three meals/day from McDonalds, claiming an average of 5000 calories/day (recommended for me at 2500/day), increased cholesterol to 230 mg/dL (starting level undisclosed), a weight gain of 24 lbs, sexual dysfunction, and a body mass index rise of 13%. Criticism of the film noted that Sperlock did not detail his day-to-day foods eaten (nor the quantities), and many observed that 5000 daily calories (double the recommended number), from any food source, absent physical activity, would result in marked weight gain. Moreover, the filmmakers conceded that the 30-day diet actually resulted in over 30 lbs. over sugar, vs. 12 lbs. of fat. Ironically, others embarked on 30- to 180-day McDonalds-exclusive diets, claiming 40 mg/dL decreased cholesterol, and loss of 20- to 60-lbs, respectively.
So, what is the correct meaning of “healthy eating”? Could it be that >40 years of government-established guidelines, with implications to our own mortality, has been wrong? While it seems the vilification of high fat has been largely refuted, is sugar now public enemy #1? While various studies now support the effectiveness of high-fat/low-carbohydrate diet in weight loss, with no short-term detrimental effects (increased serum cholesterol, fatty deposits, etc.), the long-term safety of these diets remains unknown. Moreover, meta-analyses have also demonstrated effective weight loss by low-fat diets, including Keyes’s Mediterranean diet and the Ornish Diet. It is also clear that, in laboratory animals, high serum cholesterol can be achieved by the feeding of high-fat diets, although this may be species-specific.(47) Molecular mechanistic studies, of how sugar my affect LDL formation, or fatty, artery-blocking “plaques, remain largely unknown. Moreover, it seems that inflammatory responses play a role, and whether this is a cause or effect remains unanswered (48).
Thus, regardless of the outcome of the low carb vs. low fat debate, the “take-home” message from this tale is perhaps even more disturbing, i.e., that conflicted science, by a notable few, may have been integrated into the very fabric of our society. In this case, science was strongly subjective toward one narrative. Some steps have been taken to avoid these incidents in the future, including requirements to declare possible conflicts of interest, and minimizing industry-sponsored research funding to investigators. However, in this present-day hypercompetitive, unsustainable research environment (49,50), (likely to become even more exasperated by the current governmental administration) (51), desperate investigators may turn toward non-public sources of funding, even those again expecting specific outcomes.
Another deleterious outcome of such subjective science is its effect on public opinion. For example, given the corrupt studies of sugar and tobacco, why should the average person believe in climate change, the safety of vaccines, and the safety of genetically modified crops? It has recently been posited that public opinion of science is shaped by our own intuitive theories (52), such as our instictive understanding of geology and weather as static and undynamic, even while those notions oppose scientific findings that the climate is amenable to change, even by human activity. This hypothesis might suggest that many non-scientists are pre-existently anti-science, and debacles such as this will only deepen that sentiment.