When one wishes to address the psychological aspect of obesity and its treatment, the first step is to identify the mechanisms that cause obesity. There are two behavioural patterns that can explain common 'excess' food intake:

In obesity with hyperphagia, the cause for excess food intake can be due to the constant need to snack, an unappeased feeling of hunger during the meal, or simply love for 'good-eating'. The cause can also be linked to societal factors (including physicians). It can be induced by an inappropriate diet prescription: a too restrictive diet can induce a radical change in a person's behaviour, whether or not this affects their eating habits. Thus we can admit that some eating habit dysfunctions in obese people result from their diets.

Compulsion is defined by an uncontrolled impulse towards food-intake, in general for a specific type of food (either sweet or savoury), combined with a feeling of pleasure, even when this is to fight distress and if it then creates a feeling of guilt (for instance with chocolate).
Snacking in-between meals and compulsions are two main aspects of the ordinary behaviour of obese people. Behavioural therapies for obesity, and, on the other side, support groups, target these eating-habit problems.
Re-establishing regular meals is the first step in the care given to obese people. The anarchic pattern in meal frequency that characterizes the modern lifestyle, as well as the amount of meals taken outside are all reasons why traditional therapies will fail. It is often found, when questioning obese people on their eating habits, that they commonly indulge in excessive amounts of food during meals simply because this is a 'tradition' in certain families.

While on the subject of excess eating, it is necessary to talk about bulimia:
Bulimia is described as the ingestion of a large amount of randomly selected foods unassociated with any feeling of hunger or pleasure, and carried out in a very short interval of time (2000 calories in 15-20 minutes for example). Whether or not the crisis ends with a vomiting bout will determine whether any weight gain is associated with these eating binges. These patients are mainly women and are not obese people.
Thus, the definition of this disorder excludes common obesity. It is not a feature of most obese patients, being rather of a psychiatric nature. When obese people describe themselves as ' bulimic ' this is in fact a misinterpretation of the meaning of this word. In fact, are actually speaking of compulsions.