ELI5 Calories - why raising heart rate with exercise is good but bad through stress, caffeine etc?

ELI5 Explain Like I'm 5: Bite sized answers to stuff you should know about - in a mini podcast

Why does cooked food sometimes offer more calories than its raw counterpart? If you eat a 2000 calorie meal, why can you still feel hungry after a few hours? Why is restaurant food vastly more calorie dense than preparing food at home? Why is it good to burn calories by raising your heart rate through aerobic exercise, but not through caffeine, stress, anxiety, etc?

... We explain like i'm five!

Thank you to the r/explainlikeimfive community as always and in particular the following users whose questions and comments formed the basis of this discussion: oakteach, medstudent0302, f0me, burr-0ak, ellejaexo, ubusit, catsgomooo, draganoid16, cdb03b, tsmapp, deardiary, dbx99, cptmorgan1991, stargate525 and duel_loser.

Study referenced on Association of Physical Activity Intensity With Mortality:

https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2772939

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