Just Read: Study – Wearables don’t improve weight loss – can you outrun a bad diet?

I stopped wearing a fitness tracker because it DEmotivated me, by reminding me of the times I was not meeting my activity goals

This is what an attendee said at the recent convening on Making Health Care Measurement Patient-Centered (a proxy for respecting people in health care).

This study published in JAMA a few weeks ago (September, 2016), produced unexpected (and curious) results.

Overweight and obese younger people randomized to receive wearable devices as part of a weight loss program gained back more weight than users who did not receive wearables, after an initial 6 month weight loss.

Both sets of subjects did not have significantly different rates/intensity of physical activity over the 2 year study, and their dietary intake was not statistically significant from each other (calories taken in slightly less for the wearables group at the end). Specifically, the group with the wearable did not exercise more than the group without the wearables.

I was of course curious and decided to look more closely at the data. I produced some charts below.

Here are the things I noticed

  • Subjects were randomized at the very beginning of the study, not at the 6 month mark, when the wearables were initiated. Did they know which group they were in at the beginning and did this shape their behavior?
  • I ask the question above, because the one thing I noticed in charting the data is that the group with the wearables (EWLI – stands for “Enhanced Weight Loss Intervention”), experienced a visible plunge in MVPA: “Nonsupervised moderate-to-vigorous physical activity” even before they got the wearables, that continued well past the time they had the wearables. Overall, though, across the 24 months, there was not found to be a significant difference in physical activity.
  • The subjects were placed on what are essentially high carbohydrate diets with caloric restriction, which remained restricted throughout the 24 months.

Outrunning a bad diet?

I was recently introduced to the work of Tim Noakes (@ProfTimNoakes) (about 5 years behind the rest of the world, but maybe 1-2 years ahead of part of the world) and decided to look more closely at other factors.

Focusing on the diet of the subjects, here’s what it said in the study details (supplemental materials)

All subjects will be prescribed an energy restricted dietary intervention that we have shown to effectively reduce body weight by 8-10% within the initial 6 months of treatment. This will include reducing energy intake to 1200 to 1800 kcal/d based on initial body weight (<200 pounds = 1200 kcal/d; 200 to 250 pounds = 1500 kcal/d; >250 pounds = 1800 kcal/d). Data from our research studies [14, 15] and the National Weight Control Registry [26] indicated that macronutrient composition in the most successful participants consists of 20-30% dietary fat intake, 50-55% carbohydrate intake, and 20-25% protein intake. Therefore, a similar dietary composition will be recommended in this study. However, we do recognize that low carbohydrate/high protein diets are currently popular, have demonstrated some initial efficacy, and some participants may gravitate towards this macronutrient composition, and this will be acceptable provided that total energy intake is within the prescribed range. To facilitate the adoption of the dietary recommendations, individuals will be provided with meal plans (see Appendix B), that will allow them to plan for modifications in their daily and weekly meal plans, and a calorie counter book.

So they were permitted to lower their carbohydrate intake as long as they maintained the same amount of calorie restriction. As a group they did not do this, though. They stuck to their high carbohydrate diets over the long run.

From this paper:

Malhotra A, Noakes T, Phinney S. It is time to bust the myth of physical inactivity and obesity: you cannot outrun a bad diet. Br. J. Sports Med. 2015;49(15):967–8.

Regular physical activity reduces the risk of developing cardiovascular disease, type 2 diabetes, dementia and some cancers by at least 30%. However, physical activity does not promote weight loss.

And there was the September 12, 2016 cover story of Time Magazine:

For all its merits, however, exercise is not an effective way to lose weight, research has shown. In a cruel twist, many people actually gain weight after they start exercising, whether from new muscle mass or a fired up appetite.

This study is about wearables, not exercise, because both groups of people exercised about the same over time.

However, because both groups were on a high-carbohydrate diet throughout the intervention, it’s possible that even if the wearables “worked” (they exercised more), that the results would be the same.

Still pro exercise…

I, like Bob Sallis, MD, who is quoted in the Time magazine article, support exercise for the numerous health benefits it offers – just look up any of my presentations on the topic, oh like this one:

Presentation/Photos: Quantified Community, Population Sensors at WalkHackNight, Transportation Techies

What if listening to a wearable device isn’t as effective as listening to your body? I’m going to post on another approach tomorrow….

Charts from Effect of Wearable Technology on Weight Loss
Charts from “Effect of Wearable Technology Combined With a Lifestyle Intervention on Long-term Weight Loss. JAMA. 2016;316(11):1161.” (View on Flickr.com)

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