I agree with you that moderation is the key. Not too many years ago I weighed 248 pounds but am now down to a healthier 210 taking about 6 inches off my waistline. I did this simply by moderating how much I ate, when I felt myself starting to feel full I would stop eating. It does take retraining the brain that it's ok to feel a little hungry.
RE: Is there such food that is unhealthy?