PSYA3 Explanations for the success/failure of dieting

Explanations for the success/failure of dieting

There are many reasons why people diet - One concerns health (e.g. the greater risk of type 2 diabetes when overweight) and the other involved body dissatisfaction (e.g. due to stigmatisation and prejudice).

Genetics:

1.     The potential success or failure of dieting needs to be viewed in the context of genetic predispositions.

2.     Research suggests some people are genetically pre-disposed to being overweight (e.g., influencing things such as appetite regulation, metabolic rate, fat cell quantities etc.)

3.     Stroebe (2000) - Twin and adoption studies estimate that heredity can account for between 40% and 70% of weight.

Individual differences in responses to portion size:

People who diet may be more prone to over-eating than people who do not diet. Herman et al (2005) suggest three reasons for this:

1.     Distress:

Dieters are more likely to eat when distressed than non-dieters.

Over-eating is more likely to occur when distress is `personal` and related to negative or low moods.

2.     Craving:

Dieters seem prone to experience cravings.

Reasons for this are unclear, but cravings in dieters may be heightened due to internal factors (being deprived of certain foods) & external factors (exposure to food cues)

3.     Pre-loading:

Refers to the food someone is given to eat before free access to other foods.

Suppresses appetite in non-dieters, but does not have this same effect in dieters.

This may be due to a `what the heck` response – having eaten, dieters may take the view that there is no point maintaining a diet, and eat when there is an opportunity to do so.

Herman and Polivy (1984)’s Boundary Model:

• Eating is controlled by biological pressures to keep food intake within a set range between hunger and satiety.
• Between the satiety (feeling full) and hunger boundaries (a `zone of biological indifference`), eating is largely regulated by social and environmental influences.

Dieters have this physiological control of food undermined in two ways:

1.     Because dieters impose a cognitively determined diet boundary within their zone of indifference, food intake is no longer solely regulated by biological cues. If this cognitive boundary is breached then dieters will overeat.

2.     Alternations between dieting and overeating widen the zone of biological indifference. As a result, dieters become less sensitive to hunger and satiation cues. This means that when their diet boundary is crossed, they are likely to eat more than non-dieters.

The ability of dieters to prevent breaches of the dietary boundary is weakened by factors such as distress and cravings!