I’m not sure I fully understand what constitutes the sin of gluttony. It doesn’t really seem to be a clear-cut line. Most people in the western world eat significantly more caloric value than what they need to be healthy. That’s why people have to spend hours of their week working out in gyms to make up for it. So I would think that simply eating more than what you need to be healthy doesn’t quite reach the level of sin, especially since the Church encourages us to have celebratory meals and feast to commemorate important days. My best guess is gluttony comes into play when one makes choices to hoard food or to keep it from others in order to have more for themselves. For example, if you ate this pizza hiding out in your car so you didn’t have to share it with your husband, that might be gluttony. If you neglect you other finances and your charitable giving so you can have Starbucks everyday, that would probably gluttony. Or if you spent all your money on booze or cheesecake and made your kids each Cheerios three meals a day to make up for it. I realize that the line is probably less extreme than all that, but it might be that in a society where food is so easy to come by, gluttony is just less common.