Caution: Government diet advice may be hazardous to your health

What’s the secret to healthy eating? Less carbs? More fat? Less sugar? Unfortunately, research doesn’t provide clear answers, so it’s wise to be wary of anyone claiming to have a silver bullet. Despite the best of intentions, even if the federal government wanted to improve health through better eating habits, they can’t because they start with bad information.

While they try to associate diets with diseases like obesity, diabetes and cardiovascular disease, they can’t because the dietary information comes from an unreliable source: the people consuming food. Stated simply, no one really knows what Americans are eating because the government’s method for collecting dietary information is to simply ask people what they remember eating in the past.     

{mosads}Memory and recall have long been considered woefully inadequate for scientific data collection. Yet this is what government relies on when providing advice on healthy eating. The government’s main dietary advice is the Dietary Guidelines for Americans (DGA), which was first released in 1980 and is now updated every five years.  

Its 2015 edition is guided by data on energy and nutrient consumption collected from the memory and the truthfulness of study participants. These ‘self-reported’ estimates of food and beverage consumption are frequently “physiologically implausible”, which is a scientific way to say that ‘self-reported diets’ cannot keep people alive. One study analyzing the government’s data found that a bedridden, frail old woman (i.e., a person with the lowest possible energy requirements) could not survive on the number of calories reported by the average person in the study.  

Nevertheless, these physiologically implausible dietary data are analyzed for their relationships to the development of many chronic diseases. It should be obvious that bad dietary data make for bad analyses of diet-health relations.

Meanwhile, dietary recommendations based on these bad data perpetuate perceptions that foods can be classified into a “healthy” versus “unhealthy” dichotomy. For example, the U.S. government promoted the unscientific notion that obesity and heart disease were linked to the consumption of cholesterol and fats when the “Food Guide Pyramid” was introduced in 1992.  

Back then, the government’s advice was to obtain a majority of calories from carbohydrates — primarily breads, cereals, rice, pasta, potatoes and other starches—while relegating meats, fish, eggs, and other protein sources to two to three servings per day. Fats were to be used sparingly.

Given the questionable dietary data and analyses, recent policy reversals on cholesterol and fat consumption are not surprising. Bad data = Bad analyses = Bad advice. Yet despite the lack of evidence supporting the government’s low-fat advice, only in 2010 did the DGA stop recommending limits on total fat. Meanwhile, recent Gallup polls demonstrate that most citizens remain committed to avoiding fat in their diets, with nearly twice as many Americans actively avoiding fat in their diet (56 percent) as say they are actively avoiding carbohydrates (29 percent).

In other words, even when past bad advice is overturned, its legacy still lives on. It has been recently speculated that the U.S. government inadvertently fostered dietary changes that contributed to our growing weight problem and diabetes prevalence through its emphasis on limiting consumption of eggs, butter, milk, and meat, while bulking up on carbohydrate-rich foods like pasta, bread, fruit and potatoes.

Bad dietary recommendations also affect the advice given by advocates of taxes, bans and psychological “nudges” on various “unhealthy” foods. Advocates rarely question whether these interventions exert the desired effects on disease, weight or any other measure of quality of life. Rather, their focus is to simply guide Americans toward the DGA goals, despite little concern about the accuracy of the dietary advice or knowledge about whether public health will improve.

Ineffective interventions that redirect resources away from the actual causes of disease and ill-health are one group of unintended consequence of the government’s pursuit of dietary advice. Another is that the best intentions of an army of dieticians, nutritionists and public health advocates are too frequently based on unsound science generated by bad dietary data. Calls for more aggressive interventions remain a distinct possibility, especially when advocates don’t realize that the dietary guidelines they use to rationalize their interventions may themselves be public health hazards.

Government needs to refocus its efforts toward providing empirically supported dietary guidance that relies upon valid scientific data and rigorous evaluations of the consequences of such advice. Good intentions matter, but only so much as we have a scientific basis for our advice. Only then, can we begin to address what changes in our diets and which economic interventions may actually improve public health.

Edward Archer is computational physiologist currently serving as chief science officer at EnduringFX, a data analysis company. Michael L. Marlow is professor of economics and distinguished scholar at California Polytechnic State University, San Luis Obispo.  They are authors of a recent Mercatus study with Richard Williams, “Government DietaryGuidelines: Uncertain Science Leads to Questionable Public Health Policy.” 

The views expressed by contributors are their own and are not the views of The Hill.