Motivation and eating

Question 1

What is motivation?

Answer 1

What initiates, directs, and maintains our behaviours.

Question 2

What are the 5 major motivation theories?

Answer 2

Non-related to eating:

• Instinct theories - behaviour is motivated by innate instinct which is activated by environmental stimuli.
• Maslow’s hierarchy of needs - basic survival needs are complete first before we are motivated to satisfy higher level needs.
• Arousal theory - Behaviour is motivated by the need to achieve optimum levels of arousal.

Related to eating:

• Drive-reduction theory - motivation originates from the biological need to maintain equilibrium
• Incentive theory - behaviour is motivated by internal and external incentives or rewards.

Question 3

What are instincts?

Answer 3

• Unlearned
• Innate
• Automatic
• Hard to define
• Trigger behaviours that aid survival
• Can’t explain all behaviours and are difficult to test

Example - a baby sucking on a nipple or finger places pressure on the roof of their mouth.

Question 4

What is Maslow’s hierarchy of needs?

Answer 4

1. Physiological needs
2. Safety and security
3. Love and belonging
4. Self esteem
5. Self - actualisation

Question 5

What are problems with Maslow’s theory?

Answer 5

• Hierarchy is not linear, people often have several needs at once
• Hard to test
• Culturally specific - some do not aspire towards self actualisation

Question 6

What may you do to increase arousal levels?

Answer 6

• Do sports
• Socialise
• Watch an action film

Question 7

What do you do to decrease arousal levels?

Answer 7

• Read a book

- Take a bath

Question 8

What problems are there with the arousal theory?

Answer 8

Different people have differing levels of arousal - do different things to relax.

Question 9

How do levels of arousal associate with performance?

Answer 9

When completing a complex task we perform better with low-medium arousal whereas on a simple task it is better we have between medium and high arousal.

Question 10

What are our two arousal systems?

Answer 10

• Autonomic nervous system - arouses the body.

- Cortical arousal system - arouses the brain.

Question 11

What does the ascending reticular activating system (ARAS) do?

Answer 11

This regulates wakefulness and sleep-wake transitions. The ARAS connects the reticular formation to the cortex via the thalamus, and damage to these brainstem nuclei causes a coma.

The ARAS regulates arousal and attention in the cortex by modulating neurotransmitter systems.

Question 12

What are the 3 phases of digestion?

Answer 12

1. Cephalic/reflex phase
2. Gastric/absorptive phase
3. Intestinal phase

Question 13

What is the cephalic phase of digestion?

Answer 13

It is initiated by the smell, sight, thought, or taste of food and is modulated by appetite.

Cortical stimulation triggers salivation and gastric secretions.

Preparatory processes

Question 14

What is the gastric phase?

Answer 14

This is triggered by food in the stomach.

There is a distention of the stomach and rise of pH, release of stomach HCl which activates muscle contractions.

Question 15

What is the intestinal phase?

Answer 15

Speeds or slows rate at which stomach empties to allow duodenum to process the partly digested food before receiving more from stomach.

Question 16

What cells absorb energy in carbohydrates, fats, and proteins?

Answer 16

• Carbs - glucose
• Fats - Lipids
• Protein - Amino acids

Question 17

What 3 forms is energy stored in in the body?

Answer 17

1. Fat - the preferred form of storage
2. Glycogen - made and stored primarily in the liver and muscle and used to maintain blood sugar levels
3. Protein - is broken down and used for energy when other stores are depleted.

Question 18

What is the glucostatic hypothesis?

Answer 18

Low blood glucose/glycogen levels cause increased appetite which triggers eating.

Rising insulin levels tell you that you are full and peak a few hours after you have eaten.

Question 19

What is insulin?

Answer 19

This is produced in the pancreas and acts to reduce appetite.

Question 20

How does diabetes work?

Answer 20

Insulin levels remain constantly low, blood glucose is too high so cells can’t make use of it which increases appetite and food intake. The glucose is exerted rather than used so fat stores are used up instead which induces weight loss.

Question 21

What is ghrelin?

Answer 21

This is a peptide hormone made by the stomach. Levels of ghrelin increase between meals and fall after food is consumed. Ghrelin is an appetite stimulant.

Question 22

What is PYY?

Answer 22

PYY is produced by the gastrointestinal tract. Following food intake, PYY is released into circulation and peaks 1-2 hours later. PYY concentrations are proportional to meal energy content. PYY suppresses appetite, however it is easy to overeat on a fatty meal because it takes a while to signal to the brain that you are full.

Question 23

What is leptin?

Answer 23

This is an appetite suppressant. This is produced by adipose tissue (fat), stomach, and other organs. Leptin levels are positively correlated with the amount of body fat mass and do not appear to be driven by meal patterns and instead follow a daily rhythm, peaking between early morning and midnight.
Lack of leptin leads to morbid obesity in mice.

Question 24

What is the lipostatic hypothesis?

Answer 24

Levels of body fat regulate consumption of food to maintain a stable bodyweight.

Question 25

How is leptin associated with obesity?

Answer 25

It leads to a decreased sensitivity to leptin and insulin rather than a lack of.

Question 26

What is the role of the hypothalamus?

Answer 26

It performs a variety of regulatory functions, particularly the autonomic nervous system )including metabolic processes. The hypothalamus contains receptors for many peptide hormones. - It receives sensory information from the stomach, intestines - It is sensitive to leptin, ghrelin, insulin

Question 27

What is set point theory?

Answer 27

When we fall below ideal weight our body will increase hunger and decrease energy expenditure. If we go above our set point the hypothalamus tells us to stop eating and raises our metabolic rate to burn any excess food.

Question 28

What are the problems with set point theory?

Answer 28

There are more factors which can affect body weight and body composition. Set point can be moved upwards depending on societal factors such as abundance of food, sedentary lifestyles, and labour saving technologies. People can also lower set point through dietary and exercise changes. This then arose the theory of a settling point which is a dynamic equilibrium between biological and environmental factors.

Question 29

What is positive incentive theory?

Answer 29

This theory states that we are motivated to eat not by internal energy deficits but instead by the anticipated pleasure of eating. It emphasises external stimuli such as the time of day, the sight and smell of food, and the social context.

Question 30

What emphasises how much we eat?

Answer 30

- Package size - Stockpiling and multipacks - Size of bowl and utensils - Environment - lighting, music, temperature - Effort - Social influence

Question 31

What evidence is there for positive incentive theory?

Answer 31

Weingarten (1983) - Presented rats with food at regular time intervals either following a light, or the light was just turned on at random times throughout the day. When given free choice of food, they would only eat when the light was presented if in condition where it was seen before food. Rolls, Rolls and Rowe (1982) - Variety of food on offer increases eating, more pasta was consumed when there was a variety of pasta shapes on offer.

Question 32

What is sensory specific satiety (SSS)?

Answer 32

Decrease in the pleasantness/consumption of a food once you have eaten it to satiety - eg. the idea of a dessert stomach. As you eat one food, your positive-incentive value for all food decreases, but it declines strongly for that particular food.

Question 33

What is the reward circuit (mesolimbic dopamine pathway)?

Answer 33

Projects from ventral tegmental area to: - Amygdala - Hippocampus - Nucleus accumbens

Question 34

What does the mesocortical dopamine pathway project to?

Answer 34

This pathway projects solely to the frontal cortex.

Question 35

Is food addictive?

Answer 35

Cocaine addiction reduces D2 receptors so the dopamine response becomes blunted with increased use. A similar effect has been seen in rodent studies where they are given a high caloric diet

Question 36

What are the representations of taste that develop during the first few stages of taste processing?

Answer 36

Sweet, salty, sour, bitter, umami

Question 37

Where do taste and smell pathways converge?

Answer 37

In the amygdala and orbifrontal cortex - this is how flavour is represented. In the orbifrontal cortex you have different neurons that react to different flavours.

Question 38

What did the chocolate craving study by Rolls and McCabe show?

Answer 38

The striatum and orbifrontal cortex are activated more strongly to the sight of a food that you particularly like.

Question 39

What is anorexia nervosa?

Answer 39

- Persistent restriction of energy intake leading to significantly low body weight - Intense fear of gaining weight, or persistent behaviours that interfere with gaining weight - Disturbance in appearance of body weight and lack of recognition of the seriousness of current low body weight

Question 40

What is bulimia?

Answer 40

- Recurrent episodes of binge eating - Eating more than most within a discrete time period - A sense of lack of control over eating - Compensatory behaviour to prevent weight gain eg. vomiting, laxatives, excessive exercise, fasting - self evaluation is unduly influenced by body shape/weight

Question 41

What is a binge eating disorder?

Answer 41

Eating more rapidly than normal, feeling uncomfortably full, eating when not hungry, eating alone, and feeling disgusted with oneself afterwards.

Question 42

What is hypothalamus dysfunction theory? (Biological explanation for anorexia)

Answer 42

- Disturbed hypothalamic function means lack of weight thermostat and other impaired hypothalamic functions like thermoregulatory control - Grey matter atrophy in anorexia (poor control over body temperature) - BMI is positively correlated with grey matter in the hypothalamus

Question 43

What is the biochemical imbalance theory? (Biological explanation for anorexia)

Answer 43

The dopamine system may be hypersensitive in anorexia. This has been seen as amphetamines lead to anxiety in anorexia compared to euphoria in healthy controls. This could explain why food related dopamine causes anxiety instead of pleasure in people with anorexia.

Question 44

What does the biopsychosocial approach say could interact to cause anorexia?

Answer 44

Genetic: - Inherited personality traits - Genes that affect hunger, satiety, and body weight Psychological: - Low self esteem - Need for self control - Unhealthy body image Sociocultural: - Thin body ideal - Influences from the media, family, and friends - Abundant food supply

Question 45

What is a biological explanation of Bulimia Nervosa?

Answer 45

The reward circuit is affected, the striatum and amygdala brain activity has no down regulation once food is consumed so the hunger state is retained and people are still hungry even when they have eaten.

Question 46

What is Prader-Willi syndrome and how is it caused?

Answer 46

This is an example of a binge eating disorder, for which the genetic cause is that chromosome 15 is missing genetic information. This disrupts the functioning of the hypothalamus and several neurotransmitters involved in eating. Symptoms: - Insatiable eating - Slow metabolism - Other physiological and neurological symptoms such as small hands and feet, weak muscles, tantrums, compulsivity Results in obesity and many people die in early adulthood.