The bit about sugar being a cause for misregulation of appetite was a parenthetical remark, which the rest of the comment does not depend on. That said, I think you're drastically underestimating the amount of harm sugar does. Blood sugar is one of the main mechanisms for regulating appetite, and drinking soda completely destroys its functionality.

Regarding nutrient deficiencies, I wasn't just talking about micronutrients like vitamin C, but also to macronutrients. For example, if someone's problem is that they aren't eating any fat, then no amount of low-fat food will ever suffice to make them feel full.