Saying “People are obese due to calories” is about on the same level as “Cars crash because they move” or “Your floor is dirty because you spilled coffee”. It’s entirely correct, but it’s also pretty useless.

“Eat fewer calories” is advice that’s on the same level as “Next time, instead of dropping your coffee, don’t drop it”. It’s true, and it works, but it’s also useless since that’s just not how it works. Why does someone overeat? Do they not know something is bad? Do they feel hungry all the time because of their diet? Are they eating shit because they don’t have time/knowledge/ability to cook? Did I drop my coffee because I sneezed? Did I trip over the cat? Is my floor full of random holes? Am I wearing rollerscates? The nuances make all the difference, and the nuances are what you can use to improve the situation.

“If you don’t want to crash, do not press the accelerator” is not road safety advice. “Make sure you keep your distance and check your brakes” is road safety advice.