Lec 3 - Short term influences on eating

Question 1

How many ml of water does a balloon need to be filled with before it reduces food intake? And what are the overall findings?

Answer 1

> 400 ml

Effect is weak, no diff between obese and lean

suggests Stomach distension is relatively unimportant

Question 2

Describe Camps study - shake

Answer 2

Consume shake in one of four conditions- 2 thin and 2 think, within that they also manipulated energy density- so had equal volumes but more or less calories packed in (thin 100kcal, 500kcal and thick 100kcal and 500kcal)

=Gastric emptying is slowed by increases in energy load/density - so Gastric volume was predicted by calories
=self-reported fullness was predicted by viscosity (thickness)`

This effect indicates that the viscosity may not affect satiety and satiation through delaying gastric emptying

Question 3

Zijlstra study = cinema..

Answer 3

In cinema, participants consumed three diff test meals- liquid, semi-liquid and semi-solid (so a manipulation of viscosity).
=More food is consumed in ab libitum in the liquid form as opposed to others.
=order of consumption was liquid, semi-liquid then semi-solid

Question 4

Andrade study - spoon

Answer 4

directly manipulated eating rate and meal size by looking at difference in using small vs large spoon
= Slow rates of ingestion led to significant decreases in energy intake and significant increases in water consumption.
= Despite higher energy intake upon meal completion under the quick condition, satiety was significantly lower than the slow condition

Question 5

Who said- ‘Nature will castigate those who don’t masticate’

Answer 5

Horace Fletcher (early health psychologist, developed fletcherism)

The idea that we should eat slower

Question 6

when does satiety begin?

Describe the hormone thought to play a role in satiety aand fullness

Answer 6

Infusion of lipids into the duodenum (upper part of small intestine) creates feeling of fullness. This shows that satiety typically begins before absorption (pre-absorption)

The release of cholecystokinin (CCK) which is synthesized and released in duodenum (upper part of small intestine) is thought to play role in satiety.

It is stimulated by the presence of fat, peptides, and amino acids.

CCK has multiple effects, modulation of stomach emptying and emptying of the gall bladder (contractions cause bile to enter the duodenum, which breaks fats into particles).

Question 7

Thomas et al - looked at brain activation after consumption and found..

Answer 7

used an (fMRI) task to investigate the effect of satiation

=found reduced activation in vmPFC and insula (L), hypothalamus and OFC and enhanced activation to food stimuli in dlPFC and insula (R)

Insula is important in determining bodily sensations
vmPFC and Dlpfc – associated with evaluation.
DLpfc – associated with inhibition of evaluation

= This raises the possibility that the reduced motivation to eat associated with satiation is mediated in part by enhanced activity in prefrontal brain regions important for higher cognitive functions and decision making. Activity in the dlPFC may affect food motivation by modulating reward value signals encoded by the ventromedial prefrontal cortex (vmPFC)

Question 8

what is the Preload test meal paradigm in relation to macronutrients

Answer 8

explores the extent to which different macronutrients influence food intake and associations
The degree to which you see inhibition of food intake is determined by the nature of the food. Calorie for calorie, protein is more satiated (filling) than carb, carb more so than fat. Macronutrients therefore differ in satiation effect

Question 9

Birch - pre test paradigm

Answer 9

demonstrated energy compensation using preload test paradigm in adults and children
In one condition the preload is more energy rich than the other (132 vs32 kcals) on both conditions they were offered access to buffet

=The mean total consumption (ad libitum consumption plus preload consumption) for the children on the two lunches was nearly identical (260 kcal and 269kcal in the high and low density conditions, respectively), while the adults ate 100kcal more in the high caloric density preload lunch

=children show good compensation relative to adults

Question 10

Yeomans (1996) - appetizer effect

Answer 10

manipulated palatability through three levels of oregano - bland, palatable (0·27% oregano) and strong (0.44%)
=Both intake and eating rate were greatest in the most palatable condition and were reduced in strong condition.
=Hunger ratings increased during the initial stages of the meal in the palatable condition, but fell throughout the meal in the other conditions
=this is what is referred to as appetizer effect in which palatability can increase hunger and not decrease hunger during a meal

Question 11

what happens when intake is paired with IG self-infusion of glucose rather than with water in chow fed rats? (Ramirez)

Answer 11

Chow-fed rats drink 2–3 times more saccharin solution when paired with infused glucose

Appetition signals act within a meal to promote continued intake in immediate response to gut feedback

Question 12

What is the appetition effect?

Answer 12

gastrointestinal nutrient infusions can condition flavor preferences and stimulate intake

Question 13

describe alliesthesia and who said it?

Answer 13

Cabanac (1971) = pleasure that is obtained in general isn’t fixed and isn’t a property of the stimulus but has a functional role and depends on signals relating to internal state.

Glucose load decreases pleasantness of sucrose but not salt

Eating decreases pleasantness of food-odours but not non-food odours

alliestheisa therefore moderates motivation to consume food

Question 14

sensory-specific satiety and study to prove it

Answer 14

this relates to the notion that not all foods decrease in pleasantness during a meal.

Rolls - offered three different meals (saus, cheese, then either same or opposite).
=If they are given same food as before, eg sausage then sausage there is a drop in food intake of same food in second round. But food intake doesn’t drop when they are fed the oppoisite
=Association isn’t general, it is specific to particular food that has just been consumed.

Question 15

Sensory-specific satiety .. how long does it last? what age group is highest?

Answer 15

Can last around one hour.
Can show same effect even when they don’t swallow the food
Effects food choices. .
Elevated in adolescents and decreased in older people.

Question 16

why is Sensory specific satiety adaptive?

Answer 16

SSS is regarded as an adaptive trait because it encourages the consumption of a variety of foods.

Question 17

why can we not assume that satiation and positive feedback are related causally?

Answer 17

People are very bad at discriminating between hunger, fullness, liking, preference, palatability, and so on… In the end, all of these measures tend to be correlated (see Booth, 1981).

Question 18

Difference between wanting and liking according to Berridge

Answer 18

Berridge argues that neuropsychological evidence suggests two sep processes in food reward: liking and wanting

Liking = affective processes of palatability/pleasure/displeasure.

Measured using taste reactivity paradigms (facial expressions). Opioid system.

Wanting = a disposition to eat (incentive salience)

Measured using an operant task - performed in order to obtain the next reward, e.g., bar pressing. Mesolimbic dopamine pathways

Question 19

‘Wanting’ and ‘liking’ – evidence from psychopharmacological interventions

Answer 19

Yeomans - demonstrated liking reduced but wanting preserved

Opioid antagonist drugs such as naloxone and nalmafene reduce intake and pleasantness ratings of preferred foods but have limited effect on hunger  

Blundell showed wanting reduced but liking preserved

By contrast, a serotinergic drug dexfenfluramine reduces pre-meal hunger but has little effect on sweetness or pleasantness

Question 20

Epstien et al- Two groups manipulated to be hunger or fed.

Answer 20

Measured:
Hedonics (liking): Baseline reactivity measure – using 10-point liking scale. In addition, an objective measure was obtained by behavioural coding of facial videotaped expressions.

Non-affective (wanting): Measured how hard pp was prepared to work using a snack food – a computer gambling task that provides a measure of the amount of effort prepared to exert in order to get a portion of the snack food.

=No diff in before or after eating in liking, hedonic ratings of liking showed no differences – liking was preserved pre and post meal
=But wanting was diff- the amount of work that was engaged in to obtain food was greater when they were deprived
=This paper is an attempt to differentiate between liking and wanting

Question 21

examples of pos and neg feedback

Answer 21

Development of negative inhibition:
Gastric volume
Viscosity and eating rate
Hormoncal control (CCK)
Imaging studies
Pre load test meal studies

Changes in positive feedback during a meal:
Appetiser effect and appetition
Alliesthesia
Sensory-specific theory
Wanting and liking