Gluttony means over-indulgence and over-consumption of food, drink, or wealth items, particularly as status symbols. Some faith traditions clearly label it as a sin, while some others just discourage or prohibit gluttony.
Why am I eating this? I don't know. I just want to eat. Why am I drinking this? I don't know. I just want to drink. Why am I watching this? Why am I consuming something I don't want to? I don't know.
And then we become a slave to these things, and our ability to enjoy is lessened.
Extremism
An extremist view, when looking at Gluttony as a sin, can be to decide the best thing to do is survive on bread and milk, denying oneself any semblance of earthly pleasure.
Temperance
Gluttony is "I don't know how to say no". Gluttony is described as a sin to encourage temperance.
Intemperance is, not being able to say no to the right thing at the wrong time, or the wrong thing at any time.
Everything or anything when done in balance is good, too much or too less, both are harmful. Hence I often say life is finding a balance, for each of us this balance is different.