(Credit goes to RD Daniel Schultz for finding this reference in his read of the DIETFITS study and for sharing it via his excellent Twitter thread of thoughts on same)
In case you somehow missed it (though that seems hard to imagine), last week saw the publication of the excellent DIETFITS study – a year long, randomized, controlled trial, that compared the effects of low-carb and low-fat diets, on weight loss and other metabolic outcomes.
Briefly (and if you want to read a detailed synthesis you can read this one over at Examine.com), DIETFITS found that over the course of a year, both low-fat and low-carb diets produced similar weight losses and had similar effects on various metabolic outcomes.
The coverage of the study was widespread, and integral to it was this notion that counting calories isn’t necessary for weight-loss, or that it’s less important than the foods consumed, in that this successful study’s approach involved counselling participants to eat whole foods, be they low-carb or low-fat, while eschewing the rest. Put another way, according to the coverage, people were taught to monitor and care about the quality of their calories, not their quantity, and that this was sufficient to drive significant weight change regardless of whether the foods they consumed were low-carb, or low-fat.
That conclusion is problematic for two reasons.
First, there was no study arm that explicitly taught participants to carefully track their quantity of consumed calories with no emphasis on their quality. Such an arm would be important to conclude that quality of calories trumps quantity of calories for dieters.
But more importantly, and again, thanks to Daniel Schultz, it would seem that the bulk of participants were in fact counting calories as reported by the previously published DIETFITS study design and methods wherein it was reported,
"The most common dietary monitoring method used was the on-line MyFitnessPal tool"
And as anyone who has ever used MyFitnessPal (or any of the other app based trackers – some of which were also utilized by DIETFITS participants) knows, while yes they’ll track what you’re eating, their primary end-user feedback is calories. And so even if somehow participants did not know in advance that calories were a consideration in weight loss, MyFitnessPal use would have seen to it that they learned that fact very quickly.
You see, setting up a MyFitnessPal account requires the input of a number of different variables: Weight, height, goal weight, age, sex, and some demographics.
And once input, MyFitnessPal then lets you know how many calories you should be aiming at daily to hit your stated weight loss goal.
Finally, when you start entering foods, though macronutrients are also tracked, calories are MyFitnessPal’s most prominent field whereby there’s a running calorie tally at the top of your diary, along with their meal by meal breakdown.
So while participants may not have been provided with specific calorie goals by the researchers, they were recruited on the basis of being involved in a weight loss study, and without a doubt, they all knew, that when it comes to weight loss, calories do count, and the majority of them used an app that tracked their calories, provided them with a personalized daily calorie goal based on their desired losses, and reported those calories to them prominently every time the app was utilized. And it’s difficult for me to imagine that information didn’t affect participants’ choices, and certainly is enough of a confounder so as to render the conclusion that counselling solely on dietary quality is sufficient to drive significant weight loss.
This doesn’t diminish the study’s actual findings, but when it comes to calories’ quantity and quality, it would seem that there are those who want to promote the existence of a false dichotomy stating that only one or the other of those two variables count. Honestly, I come across it all the time. Angry folks who claim that when it comes to weight and/or health, calories don’t matter at all and that what really matters is the quality or types of foods, or the folks who claim that the quality or types of foods don’t matter at all, it just comes down to calories.
It’s both of course.
The currency of weight is certainly calories, and while we all have our own unique internal fuel efficiencies when it comes to using or extracting energy from food or from our fat stores, at the end of the day, we still need a surplus of calories to gain, and a deficit of calories to lose.
But don’t kid yourself – foods matter too. Choice of food matters in terms of health, but also in terms of how many calories our body expends in digestion, and more importantly, upon satiety, which in turn has a marked impact upon how many calories, and which foods, we choose to eat (and of course to health, but that’s a whole different matter).
All this to say, the DIETFITS study is terrific, and speaks directly to my published confirmation bias that adherence to one’s dietary strategies matter far more than the macronutrient breakdown of said strategy. It also speaks to my bias that when armed with information about both the quality and quantity of the calories we’re consuming, and provided with ongoing attention and support, weight loss and improvements to various metabolic parameters are far from an impossibility.