We often associate meals with social times--holiday dinners, parties or eating out with friends. Eating in secret (rather than simply eating alone) implies that a person seeks to avoid people when eating.
This raises the question of what the person doesn't want others to see. Is it the amount of food eaten? The kinds of food? Perhaps it is simply hard to be watched while eating. Eating in secret solves all of these apparent problems.
If it is difficult to eat with another person, there is no question that negative emotions are present in some way. There may be social anxiety. Or, a person may have a poor self-image, which would likely lead him to interpret questions about food choices as criticism of him as a person.
In any case, eating in secret helps cover the emotions that would be present if another person were there. And that means that those emotions are less likely to be addressed.
