https://www.nytimes.com/2018/02/20/well ... w-fat.html
The reality: "Yes, Calories Counted (Literally) In The Recent #DIETFITS, Low-Carb, Low-Fat, Shootout Study" (Weighty Matters)
http://www.weightymatters.ca/2018/02/ye ... ly-in.html
[links to the actual study in that blog post]
\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).
I also read a comment on that blog post (on FB) that resonated with me, which is that if you're currently overweight and have a poor diet, focusing more on eating healthy foods WILL yield results. But if you're already eating well (more whole foods, less processed foods, restaurant meals and take-out), you really do still need to count calories to ensure you are running the required deficit to lose weight.
On a personal level, the challenge is that my ever-slowing metabolism is making it hard for me to know how many calories I'm actually burning at rest and during activity so that I know how much I should be eating.