On a hard stretch it's easy to run on cheap rewards: fast, always available, nothing built. The popular story is that they "burn out your dopamine receptors". The science is less dramatic: what's well shown is that these habits crowd out the slower rewards that hold mood up, like people, movement and finishing things, and that they get worse under stress.
A week off one of them tells you how much of your evening it was eating. That's information you can't get any other way. Evidence: worth trying
If stopping one turns out to be hard, that's also information. Talk to a doctor.
Same theme: The feed