Some people maybe can but most cannot. Even running like 5 miles a day is completely undone by a large frapachino. The difference in an active adult's normal day, like a teacher walking around, and a completely sedentary worker at their computer can be undone with a cream cheese bagel.

And in the US, a bunch of the food that's convenient to buy and eat is "hyperpalatable". You're going to be really hard pressed to lose and keep weight off without deliberately adjusting your diet to support it.