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A recent study validates the diet quality concept for weight control.
Written by: Matt Fitzgerald
Some foods promote weight gain. Snack chips, candy, soft drinks—call these low-quality foods. Other foods tend to prevent weight gain. Fruits, vegetables, whole grains—call these high-quality foods. One would expect people who eat lots of low-quality foods and not a lot of high-quality foods to be fatter than people who do the opposite. A recent study from the Harvard School of Public Health proves that this is expectation is accurate.
The study included data on eating habits and changes in body weight collected from more than 120,000 men and women over a period of 12 to 20 years. The researchers looked at how consumption of just a few specific high-quality and low-quality foods affected patterns of weight change over time. The average subject gained 16.8 pounds over 20 years. Data analysis revealed that almost all of this weight gain was associated with frequent consumption of low-quality foods such as potato chips and was negated by frequent consumption of high-quality foods such as broccoli.
For example, each daily serving of potato chips was linked to 1.69 pounds of weight gain every four years. By contrast, each daily serving of nuts was associated with a 0.57-lb attenuation of weight gain over four years.
When the results of this study were released last month, some late-night comics had fun mocking them. “New study shows gorging on potato chips makes you fat.” Okay, when you put it like that, the study seems like a very big effort to prove the obvious. But it’s actually a lot more profound than that.
What’s truly obvious—and the reason those jokes about the study aren’t terribly clever—is that knowing what makes people fat does not help people avoid getting fat. In theory, nothing could be simpler than losing weight or preventing weight gain. But two-thirds of us are overweight anyway, because it is not easy to actually do the simple things one has to do to become or stay lean.
What’s really needed is not greater knowledge about how to effectively manage weight but better tools with which to put that knowledge into action. And that’s why the diet quality study is important. It provides evidence that people can avoid getting fat by focusing their attention on just a few basic types of foods—classifying each as high quality or low quality—and eating more of the former and less of the latter. The very simplicity of this approach—compared to calorie counting, glycemic index-based diets, and multi-phase popular diets such as South Beach—not only makes it easy to ridicule but is also the very thing that could make it more effective. Simplicity matters.
Diet quality is such a powerful concept in weight management that it’s amazing to me how little attention it’s received. If you take the average fifth-grader’s knowledge of nutrition and apply it to a consistent monitoring of your diet quality, there’s really nothing else you need to do to attain and maintain a healthy body weight besides exercise. Yet the concept of diet quality is almost never talked about.
A couple of years ago I created a tool called the Diet Quality Score that is intended to make it very easy for the average person to monitor and improve his or her diet quality. It’s similar to counting calories but a lot easier. Foods are categorized by 11 basic types, about half of which are classified as high quality and the other half as low quality. Each time you eat a high-quality food you earn points. Each time you eat a low-quality food you lose points. Your overall point total for a whole day is your diet quality score.
To use this tool to lose weight, all you have to do is find little ways to increase your DQS by eating more high-quality foods and fewer low-quality foods. You don’t have to hit the maximum DQS of 29 every day. Just increase your DQS to the level that is needed to yield the results you seek—whether it’s 13 or 20—and then maintain it at that level.