In my opinion, worrying oneself over diet constraints when already suffering from something like ENS might only increase the anxiety and depression, not decrease it.
Besides, food causes nasal congestion, and many foods cause extra mucus secretion, two things that we need. I'm not telling people to over eat, and yes it is important to watch high cholesterol foods and to do lots of physical activity, but don't think that diets are healthy to anyone (except if you can't eat certain foods, like diabetic or zeliac patients), let alone to an ENS patient. Starving the body, decreases the metabolism which actually slows down the burn of calories not accelerates it and lowers the levels of serotonin, and most who diet end up putting more weight than they began with.
No diet will succeed without healing the emotional problem causing over eating. In ENS - it is simply stress from ENS. It will not work the other way round. One the cause of extreme stress is removed and emotions heal then the body will regulate itself and loose weight faster than any diet will.

The entire diet industry is a fraud that was invented for money making purposes only, a long-side the creation of the fast food culture. Both are American inventions. Add to this the fact that although America leads the industrial western world, the average life expectancy of Americans is lower than in other western countries by a good number of years, and a higher percentage of people that reach old age are more disabled and suffer from more chronic diseases than say in France, Holland or Italy, where the concept of diet is considered a sick joke. People don't need to diet there as much because they have a completely different outlook on life and what is really important in life.
Of course it is changing there too with the trends of globalisation, but trust me - if you look deep into the underlying processes you will see I am right.