Dissatisfaction is the glue that binds Sonnet 75's overarching theme (love) and its two main metaphors (greed and gluttony) together. The speaker's main complaint about love is that it doesn't give him any satisfaction. When he doesn't have it, he is tormented by desire. Once he gets it, he gets so much that he is sick of it. See the problem? The speaker then compares this experience of his to that of a miser who can't enjoy the money he has but can't spend it for fear of it being stolen. Then he uses this image as a bridge to the image of a glutton, who constantly feels like he's starving, until he gorges himself, and then feels sick. If you were out for coffee with the speaker, listening to the trials and tribulations of his latest relationship, you'd probably ask him to find a happy medium, for Pete's sake. Unfortunately, he probably wouldn't be able to do that, because it sounds like his relationship isn't on firm enough footing to build trust (as we learn in lines 11-12). Until the speaker can patch things up with his beloved, it looks like the Rolling Stones' "Can't Get No (Satisfaction)" will still be the song that best sums up their relationship.
Good try Mr. S., but the end of the poem is not satisfying, because the central problem is not resolved.
The unusual organization of the poem's content (2 lines on positive nutrition, 6 lines on greed, and 6 lines on negative nutrition) might be designed to reflect its basically unsatisfying nature. Coming here looking for a conventional sonnet structure? No soup for you!