How to Lose Weight: Why Stepping on the Scale Gets in the Way

The ongoing quest to lose weight goes a little something like this: you eat salads for two days, jump on the scale, then cry yourself to sleep after learning pizza was sacrificed in vain. Dan Ariely, a behavioral economist at Duke University, wants to take the tears out of dieting with Shapa, a different kind of scale that never reveals your weight. Instead, using an app and numberless scale, the device simply relays whether or not you've made progress. We talked to Ariely about why focusing on numbers can be counterproductive and how this new scale is more intuitive with the way our bodies work.

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What does this new scale measure?
So mostly, we measure weight. We measure bone density, we measure connectivity and some ideas about water retention. But mostly you can think about it as measuring weight, but the important thing is we don't report weight back to you.

Why is this a better form of measurement than traditional scales?
What we found out about the scale are three things. It's a good thing to step on a scale. It's good to step on a scale every morning, mostly because people are reminded they want to be healthy. We found that weight fluctuates a lot.

We got some new data showing that people who are obese, their weight can fluctuate up to 10 pounds a day. Part of the fluctuation depends on when you went to the bathroom and how much salt you had yesterday and so on. Part of it is that the body reacts slowly to changes. Let's say you try to reduce your weight. Your body actually tries to fight you for a while. If you're obese and you're trying to lose weight, you get this reaction against it.

How do drastic fluctuations inhibit progress?
This fluctuation creates two negative things. The first is what we call gain aversion. On days when your weight goes up, you feel really miserable. On days when your weight goes down a little bit, you feel happy, but it doesn't balance the unhappiness. On average, even if your weight hasn't gone up, the experience is negative. People expect that their body will react very quickly.

How is your scale different?
For the first 10 days, we tell them [the user] congratulations, you stepped on the scale. During those 10 days, we figure out how much their weight fluctuates. After these 10 days, we report back to people on this five-point scale. We say, you're just the same, nothing is changing you're in the green. Slightly better, slightly worse, much better, much worse. That's it.

How is hearing that you're faring worse any different than seeing a number gain? Isn't it essentially the same message?
The issue is with variance. If you went on a diet yesterday and then tomorrow you step on a scale, and the scale tells you you went up by 0.05, that's a very demotivating response. On our scale, you don't get that. Because people expect quick changes, the regular scale is just not giving them motivation. It's in fact demotivating.

Isn't the message that you're doing worse still demotivating?
Absolutely, there's no question that any feedback that you're not doing well is unhelpful. But the scale by itself is not just a tool to correct people. It's a tool to help people understand the relationship between what they do and what the outcomes are. Imagine someone stepping on the scale after Thanksgiving dinner and seeing that their weight has not increased. What is that person inferring? Maybe I can continue eating this way. So the scale by itself is not changing behavior. It's just giving people feedback that is more compatible with how the body reacts.

Your app assigns small tasks. How do these help with weight loss?
We took everything we know about social science, basically little tricks that help people be healthier. So when you open the app you get a recommendation for missions. Many of the missions are things like reorganize how your refrigerator looks, or let's create a shopping list.

Can you give an example of a mission that serves as a diet hack?
People open the refrigerator, they don't have a plan of what they're going to eat. Instead, they see what comes to mind when they open the refrigerator. So the things at eye level end up being much more important. So if you wanted a strategy to do something for health, putting the healthy food at eye level is a good strategy.

What kind of people will this scale work best for?
It's mostly for people who want to change their weight. They understand it's a good thing to step on the scale every day, but they understand it's also heartbreaking and want to get better feedback this way.

The Shapa scale costs $129, and a one-year program subscription of $9.99 per month is required.