Objective / Subjective

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Numbers. Nutrition and exercise are full of them. We can tabulate calories and grams, measure portion sizes, count servings, and analyze food journals. Thanks to various electronic gadgets and apps, we can keep tabs on our steps, estimate our metabolic rate, and track other biomarkers.

As a guy who holds a degree in mathematics and used to work as a research analyst, nobody loves objective data more than I do. When I began my career transition and was moonlighting as a personal trainer, I made use of several physical tests – the Rockport walking treadmill, the sit-and-reach, the list goes on – to quantifiably track my clients’ progress over time. My career as a dietitian started off similarly, as I relied heavily upon bioimpedance analysis data, weight, and estimated macronutrient needs to guide my nutrition advice.

Imagine my surprise when, through a combination of additional education and experience, I realized how little these quantitative data actually matter. On the first day of the first nutrition course I ever took, the professor began with a brief survey of the social, cultural, personal, and financial factors that influence eating behavior. In our diet-minded society in which food is thought to be just fuel and any persuasions to the contrary are seen as weaknesses and sources of guilt, we easily forget how important this basic truth really is.

One of my patients recently told me that his wife purchased a diet book that emphasizes the glycemic index and she would like the two of them to begin eating in accordance with the author’s guidelines. Objectively, the glycemic index, which is a measure of how quickly various foods raise blood sugar relative to a standard (usually white bread), makes some sense. If a food breaks down more slowly, we stay full for longer, eat less, and consequently lose weight. At least, that is what the book’s author wants its readers to believe. Just aim for the low-number foods on the glycemic index chart and we are all set.

Right around the same time my patient told me about this book, another patient relayed to me an experience he had regarding hamburger buns. His parents typically made burgers on whole wheat slider buns that he thought were okay – not great, not awful, but okay – and he normally ate two or three burgers as the meat from the normal-sized patties jutted out beyond the rolls’ perimeter like a UFO. For reasons that remain a mystery to my patient, his mother decided to make burgers on normal white buns one evening. In contrast to their whole wheat counterparts, these white buns hit the spot. He had one burger, felt satisfied, and stopped eating. Turned out that for him, the white bread, which is sky high on the glycemic index, was actually the better choice and kept him from overeating.

The more I work with my patients, the more I am reminded of how the subjective is often of greater importance than the objective, that the qualitative usually trumps the quantitative. Numbers still have their place, for sure, but they really only play a supportive role. This, I have learned, is one of the most significant differences between nutrition on paper and nutrition in real life.