Nutrition Science: Imprecise Discipline, Still the Best We’ve Got to Work With

Nutrition experts and health counselors dispense endless advice on how to eat right and stay healthy, but apparently to little avail, considering the ever-growing obesity crisis with all its devastating effects on public health. Why is that? Is it that people don’t pay enough attention to professional advice, or is it that the professionals don’t really know what they’re talking about?

In a recent op-ed article in the New York Times, Gary Taubes, a well known health and science journalist, stated that nutrition science as it is practiced today may be doomed to failure because it is an imprecise undertaking that is based on opinion and guesswork rather than strict scientific principles.

The hypotheses nutritionists follow are little more than speculation, he says, because the gold standard of science — clinical trials and randomized controlled trials — is not attainable in this field, as it would be prohibitively expensive and exceedingly difficult to conduct such strict testing.

What would it take, for example, to prove that certain eating habits lead to obesity or diabetes, he asks. It would mean to convince thousands of people to change their diets for years or decades. Many would have to die of heart attack, stroke, cancer and other causes based on the dietary regimens prescribed to them. And all this just to find out whether dietary intervention would have made a difference.

Since none of this seems feasible (or morally permissible), the standards of nutrition science are inevitably sub-par in comparison to other scientific disciplines. Accepting lower standards of evidence, however, means that nutrition science will never measure up and, therefore, cannot be taken as seriously as its proponents claim.

But what are these ideal standards of science anyway? Taubes uses a definition first introduced by the philosopher Karl Raimund Popper with his principle of empirical falsification — by which he means that scientific theories based on observation can ultimately never be proven and must be continuously scrutinized through further experimentation.

But is that really the only standard we should subscribe to, considering how multi-faceted scientific research is, especially when it applies to real-life issues? In practical terms, we rarely comply with the absolutistic standards Taubes is referring to. We work with what we think to be true, or at least probable, and build our theories and hypotheses as best we can. We live with imprecision and uncertainty every day. We have no choice, otherwise we could not function.

As dietitians and nutritionists we know a thing or two about the human body. We know that if your calorie intake is higher than your expenditure, you will likely gain weight over time. There may be other factors involved, but this is surely one of them.

We also know that food consumption has substantially increased over the past few decades, both in restaurants and in homes. We know that people eat out more often than they used to. We know that home cooking has been declining due to social changes like more women entering the work force. We know that processed foods have become predominant in many people’s diet and that some ingredients like fat, sugar and salt can have detrimental effects on nutritional health. And we know that most folks, including children, don’t exercise enough, and that a sedentary lifestyle contributes to weight problems. We may not have ironclad proof for each and every one of these issues, but we have a pretty good picture of what’s going on, what’s driving the obesity crisis and many other related ills.

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Timi Gustafson
Timi Gustafson, RD, LDN, FAND, is a clinical dietitian and author of the book, The Healthy Diner: How to Eat Right and Still Have Fun, which is available on her blog, Food and Health with Timi Gustafson R.D.. Follow Timi on Twitter, Facebook, and Google+.