It’s been all over the news these past few weeks, a recent study reported that not only didn’t wearing a FitBit as part of a weight loss program lead to increased weight loss, it led to decreased weight loss.
Does it really matter one way or the other?
The question that matters is whether or not FitBits led wearers to exercise more, not whether it led anyone to lose weight.
According to that same 2 year study, the answer to whether or not FitBit users moved more was no.
That’s both disappointing and not particularly surprising. It’s disappointing because moving more can markedly improve health and quality of life at any weight. It’s not particularly surprising because no one has yet figured out how to affect a population based sustained increase in physical activity.
No doubt there are specific individuals who are motivated by their trackers and do in fact sustain long term changes to behaviour, but once again here we have an outcome that speaks against the ongoing singular focus of personal responsibility as the means to improve healthy living.
If we want people to move more we need to find ways to make doing so easier, more fun, and/or more valuable. Simply telling them to move more, or apparently showing them how little or how much they move, isn’t going to be enough in and of itself.
[UPDATE: The study though did have a major limitation in that it used a now obsolete wearable. It’s possible that the results with newer wearables would differ. Here’s Aaron Coleman’s coverage of same. Thanks to @Chimbo23 for pointing me to it.]
Among the biggest frustrations in scientific knowledge translation is the extrapolation of outcomes from mouse studies to humans. It’s frustrating because most people aren’t just large rodents, and yet those mouse studies and their resulting press/publicity, are often used to push agendas. And it happens with diet studies too.
Simply put, we can’t make conclusions of human diet outcomes based on studies conducted in mice.
But can we even do so in mice?
It seems like there are 3 huge confounders for mouse diet (and other) studies.
The first is that a mouse’s living arrangements (eg. noise, bedding, light, the pH of their water, and more) can markedly affect study outcomes.
The second is fecal-oral eating. Yes, mice eat each others’ feces, and if we’re talking the impact of diet on health, knowing which mouse ate how much of whose feces and what said feces contained might matter.
And lastly there’s this tweet by Emily Deans who was recounting Ronald Kahn’s experiences that noted that strains of genetically identical mice have different metabolic responses to identical diets (which may speak to the living arrangement issue, or to differing microbiomes, or both).
All this to say, in free-living humans diet studies are anything but simple, and even in mice captive mice, the control of confounding variables is challenging.
Many people worry that consuming artificial sweeteners will lead to increased overall eating consequent to either the induction of hunger, or by way of simple “energy compensation“.
A recent sugar industry funded study set out to explore that possibility.
The REFORM study looked at the impact of an 8 week crossover swap of ultra-processed sugary foods with ultra-processed artificially sweetened foods on 16 active young men and 34 active young women whose average BMI was 23.5 and whose average daily step count was 9,064. For 8 weeks they’d consume either sugary stuff or artificially sweetened stuff with a 4 week washout period in between and they were blinded to which treatment they were in.
The researchers were looking at a number of different variables including of course sugar consumption, but also body weight, energy intake, energy expenditure, blood pressure, arterial wall stiffness, fasting sugars and lipid levels.
At baseline the researchers report that the average daily energy intake of participants was a mere 1,900 or so calories, dramatically less than their reported predicted baseline energy intakes of 2,400 calories per day. They also reported that though blinded to whether the products they were consuming were sweetened with or without sugar, 83% of participants correctly identified which was which.
Though the researchers reported a decrease in the consumption of sugar consequent to the intervention, what they did not see was a change in body weight which in turn led the researchers to conclude that subjects compensated for the lesser calories found in artificially sweetened processed foods by eating more. They also didn’t see any other changes in the other measured outcomes.
I’m neither excited nor disappointed by this study’s findings as I just don’t think any conclusions from it can be drawn. The small number of subjects in this very short study were young, active, and thin, their ability to accurately report their dietary intake was clearly inadequate, and the study, though blinded, wasn’t well blinded given the vast majority of subjects were able to correctly identify which treatment arm was which.
I’m blogging about it today not so much because I think it’s important as a study, but rather because I saw a bunch of folks I respect tweeting about it as if it provided new and valuable insights – an opinion I don’t share.