The sins are very different in type:
Masturbation is a categorical sin. It is always wrong. There is no need to masturbate and there is no biological purpose served in it (putting aside the debatable claims of health benefits to masturbation). As noted earlier, sex is for unity and procreation, and masturbation serves neither purpose.
Gluttony is a sin of degree. Eating/drinking are perfectly acceptable; it is only when done in excess that they can become sinful. We need to eat and drink. Even ice cream (contributing fats and sugar) and soda (sugar, hydration) offer some nurtition. In the western world, such nutrition is often in excess to what we otherwise consume, but offer such foods in developing countries and they’ll be gladly received, where pure calorie intake is very important. As noted, it is temperance that helps us avoid eating/drinking from becoming potentially sinful activities. It may sometimes be hard to know where to draw the line…I’m sure many of us carry a few extra KGs/pounds than we should…but it’s an entirely different matter to masturbation, where the line is clearly draw at “don’t do it”.
So ice cream (beer, wine, chocolate, soda, etc) in moderation, as part of a healthy diet, is fine. Masturbation in moderation is inherently wrong.
The better analogy might be between masturbation and artificial sweeteners, which serve no nutirtional purpose. Yet even artificial sweeteners are usually taken in the context of other nutritional food - eg diet soda still offers hydration. So perhaps, as others have noted, the best analogy is between masturbation and the Roman purge - throwing up to avoid the nutritional effects of the food consumed and to indulge further in their pleasure, removed from consequences. Hopefully it’s clear enough that this is disordered?
