When Less Information Is More: Why Vague Feedback Helps Weight Loss

We are on a never ending quest for precise information. Just take the bathroom scale as an example. Several years ago we were happy to stand on the scale and get an estimate of how many pounds we weighed plus or minus ½ pound or so. Now, we can buy scales that give us feedback about our weight, % body fat and even hydration levels to three decimal places out.

The more specific the information, the more in control we are, and the better we will be at managing our weight and reaching our health goals. Right? Think again. New research out this week at the journal Psychological Science shows that vague information sometimes serves people better than precise information does.

As it happens, when you get precise information about how much you weigh, it forces you to be objective about your expectations for future weight loss success. For instance, let's say your goal is to lose 6 pounds in a month. After two weeks of dieting and exercise, you get on the scale and find you have lost exactly 2 pounds. Yes, 2 lbs is progress, but it's also pretty far from your 6 lb goal. Knowing that you still have a ways to go may mean you stop trying so hard to achieve your goal. You become lax about your eating and exercise habits and, before you know it, the 2 lbs are back on. However, if, instead, after two weeks of dieting, you receive information that you have lost somewhere between 1 and 3 pounds, it still seems possible to achieve your month-long goal. Not knowing precisely how you are progressing leads you to generate positive expectancies about meeting your goals. In return, you try harder and are ultimately more likely to succeed.

To demonstrate the benefits of vagueness, researcher Himanshu Mishra and colleagues at the University of Utah asked volunteers interested in losing weight to participate in a three week health program. Each week folks were given information about how they scored on a new type of health index - the Holistic Health Index or HHI. The index, people were told, reflected the healthfulness of the lifestyle an individual was maintaining and was being tested as a replacement to the standard Body Mass Index (BMI). The HHI is fictitious by the way, but the people in the study didn't know this. Every week, folks' weight and hydration was measured and they were given feedback about their HHI.

Some folks were told precisely what their HHI was and how it compared to the ideal. Others were given an HHI range that varied + and - 3% from the HHI's given to the precise information group. What the researchers found was that vague feedback led to more weight loss than precise information. Vague feedback seemed to provide an illusion of proximity to the ideal HHI, making it appear more achievable. As a result, people's motivation to lose weight increased and they lost more weight because of this.

People spend billions and billions annually on weight loss programs where every day or every week they get very precise information about how they are progressing to meet their weight loss goals. But, there is a lot of data out there suggesting that folks drop the programs when they don't see drastic signs of progress. This new research suggests that giving people vague (rather than precise) feedback about how they are doing might be a better way to go. Vague information allows people to interpret their progress in the most favorable way, which means they end up being more likely to stick to the plan. The end result is a healthier lifestyle in general.

For more on connections between the mind and body, check out my book Choke!

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Mishra, H. et al. (2011). In Praise of Vagueness : Malleability of Vague Information as a Performance Booster. Psychological Science.