Which has more calories?
- One ounce of chocolate or five ounces of bread?
- One teaspoon of ice cream (premium, high fat type) OR one pint of cottage cheese?
- One teaspoon of corn oil OR ½ teaspoon of pure animal fat?
Professor Paul Rozin and his colleagues obtained answers to these and other questions about nutrition from 184 college students, 121 physical plant (blue collar) workers, and 81 randomly selected adults. The following graph shows the bases for the correct answers:
In view of the dramatic differences in calories among the choices shown in the graph, you might think that most people would pick the correct answers. Did you pick them correctly yourself?
The researchers found that the following percentages of people picked the wrong answers:
- Chocolate: 75%
- Ice Cream: 56%
- Animal Fat: 78%
If people had absolutely no idea about the correct answers, then we’d expect 50% correct/incorrect responses, not 75% or 78% incorrect. Clearly most people believe the wrong answers were the right ones. At a time when most adults are either overweight and/or have dieted repeatedly in their lives, why would such seemingly obvious nutritional facts get confused by so many people?
The authors of this study suggested several explanations. First, apparently most of us try to simply our worlds by viewing things in simple categories, like good or bad. Also, a type of distortion in reasoning accompanies this categorical thinking: the principle of contagion (first described by writers 150 years ago). That is, if we view a food as bad, then we think that even small amounts of that food is tainted or bad, too. The badness of the food apparently is viewed as contaminating all of it.
Categorical thinking leads to thinking in terms of contagion, which in turn makes us insensitive to dosage effects. This means that we often fail to recognize that small amounts of some substances can help us, whereas large amounts cause problems.
Examples of this dose insensitivity abound. For example, our bodies need small amounts of fat in the diet (3-5 grams), whereas 100 grams of fat per day creates serious problems – and even a quarter of that amount is probably too high for effective weight control. In a similar way, small amounts of vitamins improve health, whereas overdoses can kill us. Moderate exercise greatly improves fitness and effectiveness of weight control, but excessive exercise can cause serious injuries.
Many millions of intelligent people have followed dietary recommendations that are as incorrect as the nutritional choices made by most people in this study. We’re obviously quite susceptible to biased thinking (categorical, contagious, dose insensitive) about nutrition and diet. These biases merely reflect a very natural tendency to keep our lives simple and predictable. In this incredibly important arena of health, however, now is the time to adjust those biases. It is time to rely on science to help you decide how to eat and stay healthy. Science clearly tells us that very low fat eating and lots of movement and exercise contribute to success at lifelong weight control; low-carb dieting does not.
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*Rozin, P., Ashmore, M., & Markwith, M. (1996). Lay American conceptions of nutrition: Dose insensitivity, categorical thinking, contagion, and the monotonic mind. Health Psychology, 15, 438-447.
Tags: Weight Loss