Why We Forget What We Eat

Source: Jacob Wackerhausen/iStock

Many programs focusing on behavioral changes to improve diet and lose weight start with self-reporting food and beverage consumption. This approach helps the practitioner and the client gather some valuable information. It gives everyone a starting point.

Further, self-reporting long term is very useful. There has been quite a bit of research showing that self-monitoring food intake is a strong predictor of long-term weight loss.

It would appear that self-reporting is one of the keys to successful lifestyle interventions. It keeps individuals accountable and aware. It also helps to document progress, which can be motivating.

Truth or Consequences

But, there are some problems here. Research tells us that underreporting of food and beverage consumption is rampant, if not almost normal. This can throw a monkey wrench into a behavior change process. The specifics of what is underreported need to be teased out and addressed.

Self-reporting often involves a 24-hour recall. After all, it is not likely that a person can be locked up or followed around 24/7 to see what they are eating. Recalling what one ate can be fraught with inaccuracies. And, yet, pooling data from 24-hour recall is often used to come up with information about how we are eating.

For example, a recent article indicated that only 5 percent of Americans get the recommended amount of daily fiber in their diet. It is quite possible that this is an overestimate of the actual number if people underreport intake of processed foods and overreport healthy foods (which, as it turns out, is the case).

Some other research using self-reporting uses those data to determine the connection between diet and development of certain diseases. The inaccuracy of self-reports means that correlations to disease are not robust.

Who, When, and Why

To start to solve the problem, we can look at why people can end up misrepresenting their food intake. To be clear, misrepresentation may be inadvertent, almost subconscious, or based on a guess. People are not blatantly trying to be sneaky. They are just being human. Indeed, unreliable self-reports are a common feature when humans monitor their own behavior. Perhaps some people are trying to save face or side-step some guilt, or they suffer from a lack of knowledge.

Science has taken a look at the who, when, and why of underreporting by using various methods to compare self-reporting to actual consumption. Research cannot account for all the variables involved, which limits the absolute accuracy of findings. Having said that, here are some of the more consistent findings:

• Individuals in lower socioeconomic segments tend to underreport processed and high-calorie foods.
• Obesity is a consistent correlate to underreporting.
• Afternoon snacks are the most frequently underreported.
• Women are more likely to underreport than men.
• Dieters (called restrictive eaters) are often in the group of underreporters.
• Some people succumb to wanting to project an image of a person who eats in socially acceptable ways. This leads to under-reporting.
• Carbohydrates, especially sugary foods, and fats are underreported more often than proteins.

Is there a bottom line here?

While the self-reporting road can be rough and tangled, perhaps the main thing is to acknowledge that underreporting is very common. We can watch for it in interventions and weight-loss programs. More broadly, those of us who are not in a program can benefit from knowing how easy it is to dip into mindlessness as we go about our days.