A Fail For Activity Trackers: The I Told You So’s vs Need More Datas


Perhaps the normally measured physician-economist Aaron Carroll best captured the reaction and sentiments of the healthcare community in response to a recent JAMA article demonstrating that subjects in a weight reduction study using activity trackers lost significantly less weight than those in the control group:

“I TOLD YOU SO!!!!!!” (Emphasis in original.)

These results were cheered for several key reasons.

First, many in healthcare are irritated by the idea of simplistic technical fixes for complex medical (and social) (and cultural) (and economic) problems–like obesity.

Second, as Carroll has pointed out, exercise is healthy for many reasons, but weight loss is probably not one of them; changing your diet seems to matter a lot more.

However, it’s important to critically evaluate research even (especially) when it seems to produce an ego-syntonic conclusion–a conclusion with which we so strongly agree.

My initial reaction to the result was that perhaps it reflects an example of the concept of “moral licensing” that Malcolm Gladwell discusses so thoughtfully on his Revisionist History podcast–i.e., when you deliberately act morally in one context, you may be more likely to act less morally in another context, having already demonstrated to yourself your moral bona fides.

The analogy here would be that perhaps, by wearing an activity tracker, you might have demonstrated to yourself your commitment to healthy behavior–and thus be more likely to act permissively in other contexts (i.e. you might actually exercise less, or eat more). This would be similar to the tendency of enhanced safety features like seatbelts leading to more risky behavior.

Yet upon further review, what’s the most striking conclusion of the paper was that although a significant difference in weight loss was observed, “Differences between intervention groups for physical activity and dietary intake were not significant.”

Did you get that? The two groups apparently ate the same and exercised the same, and yet one group lost significantly more weight. To me, this is really the paradox of this paper, the observation that doesn’t make sense.

The authors acknowledge as much–in a somewhat understated fashion–in their conclusion:

“In this study, the addition of wearable technology to a behavioral intervention was less effective for 24-month weight loss. This may be a result of the technology not being as effective for changing diet or physical activity behaviors compared with what was achieved with the standard intervention; however, the study found no significant difference in these measures between the standard intervention and enhanced intervention groups. Thus, the reason for this difference in weight loss between the standard intervention and enhanced intervention groups warrants further investigation.” [Emphasis added.]

I’ll say!

The real mystery of this paper isn’t why the addition of wearable trackers doesn’t produce weight loss; rather, it’s what to make of data demonstrating differences in weight loss despite comparable amounts of physical activity and dietary intake.

3 replies »

  1. Wearables in unfortunately just another way companies can extract money from consumers.

  2. Good analysis, David, to which I’ll state the obvious: wearables are most likely to benefit those who believe they can benefit from them. RCTs don’t control for faith in technology.

    To me it’s another demonstratively uninformative piece of research. I’ll continue to count my steps, & measure my abdominal circumference for vanity, not CV health, or all-cause mortality reduction.

  3. It’s interesting that obese people and thin people burn the exact number of calories they take in–if their weight is stable.

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