As I am totally unhealthy, i'm not sure that i'm really the right person to respond but just my two bits worth>.
Anyone who is not eating a reasonably healthy diet is likely to get sick or be more prone to moods (due to such things as highs & lows in blood sugar) both of which would make them less happy in general & also less pleasant to be around as well as less productive (you don't work your best if you're not feeling well/happy etc) but their poor eating habits would also have a negative effect on the productivity of others - if a person is rude or thoughtless to you or not doing their share of the work then your productivity suffers too.
So poor nutrition affects those you work with as well as you.
Another point to consider too is that so many people have reactions to the over processed foods, fats, carbohydrates, sugars (from add/adhd to irritable bowel syndrome - ibs) and while these allergies/reactions, inability of the body to metabolize certain foods (eg in ibs) go undiagnosed &/or untreated people will feel & sometimes actually be quite ill - this can affect them emotrionally, behaviourally & physically or all of these.
The importance of decent/reasonable nutrition (of a type that does not negatively affect you) is heightened by the pressures of todays lifestyle & work places.
Saving 
