Metabolism has to increase to incorporate a new source of load in daily life. When I started my job my feet were in constant pain but now I can stand for 7 hours with ease and I can stoop, kneel, lift with relative ease. That is just with 2 months from going from slug to lug. It takes too much discipline to hold an excercise routine for me but this new job is the right amount of activity without too much skelital stress.

But if people drink monster drinks and eat candy bars while doing all this, it won't make much difference. I still eat candy. I guess I just don't plan on doing it daily.

Pardon the spelling, I'm using a browser without a spell check.

"Much" is kind of meaningless here. If you increase your BMR by 100 calories a day that's huge because losses or gains are made at the margins.

My main point is that you need something that's not optional. If you cycle to work once a week that might be a 300 calorie deficit and it's not some sort of task you can "fall behind on", it's an integrated part of your routine now that you'd have to deliberately not do.

The specific example doesn't really matter, more just that it's not some fad "I'll make myself suffer at the weekend on the treadmill" or whatever.