Lec 8 - Dietary Restraint Flashcards
Externality Theory of obesity and who?
Schachter’s theory of obesity in 1960’s’1970’s, He compared eating behaviours of obese vs normal on empty vs full stomach.
This theory proposed that obese people are more reactive to external food-related cues, and less sensitive to internal hunger and satiation cues than lean individuals.
No diff in overall consumption
Nisbett support for..
Schachter’s Externality Theory
He found that obese people ate more in response to more palatable ice cream.
Schachter and Gross - manipulating time
The external, food-relevant cue, “dinner time,” was manipulated so that 22 obese and 24 normal Ss entered an experimental eating situation believing it to be later or before their regular dinner time.
=Obese Ss ate more when they thought they were eating after their regular dinner hour than they did when they thought that they were eating before their dinner hour. There is no such effect for normal Ss.
Perhaps such individuals are people are responsive to time as opposed to internal state.
what is the Externality theory?
predicts that the taste of food will have greatest impact on the behaviour of overweight participants because the obese are more sensitive to external cues.
whereas eating occurs in normal people in response to
‘internal signals’ (e.g., gastric
contractions, hunger, and satiety)
Nisbett’s set point theory
. Obese individuals keep their bodyweight below a biological (homeostatically defended) ‘set point’ (due to societal pressures to maintain lower weight). This then results in chronic hunger and thus overeating
Paradoxical interpretation:
People are overweight by societal standards But, biologically, they are underweight
Externality causes obesity vs “Obesity causes externality” .. who says what?
Schacter - externality causes obesity
Nisbett - obesity (attempts to limit intake) cause externality
Herman and Mack study
and what would Nisbett say?
Randomly assigned to one of 3 conditions- no taste, one taste or two tastes (each taste involved 7.5oz milkshake)
Then told to taste and rate a large quantity of ice cream and they measured ad lib.
=Unrestrained are responsible to internal cues, with increasing number of preload milkshakes, they reduce further consumption.
=Restrained less responsive to internal and eat more ice cream after consuming larger amount of ice cream.
=the preload disrupts any inhibitory mechanisms. This is like psychological explanation - a motivational collapse
=in restrained eaters, the milkshake is like an appetizer effect, you can prime hunger. Therefore attempts to lose weight cause externality (more responsive to extneral cues). This is consistent with Nisbett’s view that restrained eaters are more hungry. This is like biological explanation.
Polivy 1976 study
examined both explanations of restrained eaters overeating..
Subjects were assigned to one of four preload conditions (high - 750 or low calorie 325, and receiving true or false information about caloric value). All participants consume 8oz chocolate pudding. Subjects were then allowed to eat sandwich quarters ad libitum in order to assess the effect of the preload on consumption. so they looked at
Q. What are the independent effects of actual calories and perceived calories?
=high restrained eaters ate more sandwich quarters (about 20%) in perceived higher energy (most in actual higher) – consistent with Nisbett, bio view.
=low restrained eat lowest in actual high
= Neither restrained nor unrestrained subjects regulated their eating on the basis of actual caloric value of the preload - The difference between the means of the two perceived low is small – more consistent with psychological, relates to concept of disinhibition
Herman and Polivy’s (1984) Boundary Model of Eating Regulation
where is zone of bio indifferences?
where do psych factors exert their influence?
what is the third boundary?
who has a larger zone of bio indifferences?
In unrestrained both hunger and satiety are aversive. Between these two you have zone of biological indifferences. It is in this middle range that psychological factors are likely to exert their influence. Individual differences are assumed to exist in terms of one’s placement in the overall model.
In unrestrained , if there is no preload, they continue to eat and eat until satiety, so quite a large meal will be consumed. But if there is a preload, there is progress towards satiety and so you eat smaller meal.
In restrained there is a third boundary known as diet boundary. If you eat no preload, you eat until you meet diet boundary (eg I am restricting food intake so stop). If you have preload, the diet boundary has been transgressed and you move away from that and therefore eat like unrestrained eater up until satiety.
Because restrained eaters are often doing this, they learn to tolerate larger meals and so satiety is shifted to the right, similarly they can tolerate more hunger. So their zone of biological indifference is wider than unrestrained eaters.
Model is descriptive – does not refer to mechanism
Federoff et al 1997 study
- investigated the effect of pre-exposure to two types of food cues (olfactory and cognitive) on food intake by restrained and unrestrained eaters.
= Restrained eaters ate significantly more than did unrestrained eaters after exposure to the food cues. There was no difference in food intake when there was no pre-exposure to the cues.
=Was also found that merely thinking about pizza (cognitive condition) prior to eating increases intake in restrained but not unrestrained
Odgen and Wardle - cog shift
Measured cognitions associated with the ingestion of high-calorie foods. State of mind is characterised by cognitions such as: “rebellious” “challenging” “defiant”.
Also get the “What the hell effect” and “I’m just going to stuff my face”.
Heatherton, Herman and Polivy study
Restrained and unrestrained subjects were subjected to one of three distress manipulations prior to an ad lib taste task. These were shock, failure (being made to feel like one) and speech (anxiety and stress provoking). And compared to control group
= The physical fear threat (anticipated electric shock) significantly decreased unrestrained subjects’ eating and slightly increased restrained subjects’ eating.
=Both ego threats (failure at an easy task or anticipating having to give a speech) significantly increased restrained subjects’ eating but did not significantly suppress unrestrained subjects’ eating
=restrained eat most in speech condition!
what is the difference between dieting and dietary restraint?
Dieting = attempt to restrict intake in order to lose weight
Dietary restraint = any attempt to limit intake
You could be restrained eater who is limiting intake to maintain body weight but only a dieter if trying to lose weight. So not all restrained eaters are dieters.
Dieters are more likely to be in negative energy balance. Also, dieters and restrained eaters ‘disinhibit’ under different conditions.
how many 16 year old girls attempt to restrict their intake?
what are some health outcomes of dieting?
1 in 3
Osteoporosis. mood swings, dep, delayed sexual maturation
Green and Rogers study
=the current dieters tended to display slowest simple reaction times and poorer performance on an immediate memory task (compared to high/low restraint)
= The dieters, however, if anything, displayed the fastest tapping rate
= dietary-induced dissociation between motor behaviour and higher level cognitive processing.
