wk3_L5. Introduction to bio-psychology of eating - APPETITE

Question 1

Why do scientists study eating?

Answer 1

1. Eating has big impact on health 2. Eating is big business 3. To get people to eat more/less, need understanding of what makes them eat…

Question 2

What is Obesity; Fat?

Answer 2

Determined by BMI. Body mass index = weight in kg / height in M2 BMI provides estimate of how much fat you have Normal BMI is 18.5-25; 25-30 overweight & 30+ obese

Question 3

How do we control food intake? Which factors link > Eating?

Answer 3

BODY & ENVIRONMENT together activate BRAIN followed by EATING

Question 4

Control of food intake; role of BODY

Answer 4

Body - Biological

• Energy levels: Short-term store using glucose & Long-term store using fat
• Changes in body fat affect appetite. Fat cells secrete hormone Leptin - more fat = more leptin, suppressing appetite. Less fat = less leptin, allows food intake to increase
• Sensation: Flavour drives intake. We are hardwired to like sweet, salty & fatty things.
• Sensory specific satiety slows intake in a meal. More we eat a food, the more our liking of it declines. It acts to signal the end of a meal & drives dietary variety.
• Digestive Organs: Multiple systems involved in digesting food - all send status signals to brain. These signals communicated via Nerves (e.g. vagus), Hormones (e.g. CCK & ghrelin), Nutrients (e.g. blood lipoproteins)

Question 5

Control of food intake, role of BRAIN

Answer 5

• Neurochemicals modulate eating. 2 important examples serotonin (SE) & dopamine (DA). Increased levels of both suppress appetite.
• Neurochemicals are modulated by events in the body. Leptin stimulates release of CRH in brain (corticotrophin releasing hormone) suppressing appetite. Ghrelin (from stomach) stimulates NY release (neuropeptide Y) in brain, increasing appetite
• Brain Locations: HYPOTHALAMUS - ventromedial nucleus (stop eating), lateral hypothalamus (start eating). CRH & NY exert effects here. CORTICAL - frontal (impulsivity), insula (interoception). LIMBIC SYSTEM - hippocampus (memory), eating & HM

Question 6

Control of food intake, role of ENVIRONMENT

Answer 6

Show you food - desire triggered. Food is everywhere; Ad’s, snack machines, coffee shops etc…. Few social prohibitions on eating

Time & Place day after day becomes associated with eating.

Social Facilitation of eating: how many people are we with? More people > more eating.

TV as an appetite stimulant

Portion and plate - big plate = big meal = more eaten

Question 7

Who is in charge of eating - body, brain or self?

Answer 7

• Main drive is environmental factors we aren’t aware of (mindless eating)
• Biological factors only important in extremes (starvation/over indulgence)
• Conscious control plays small role

Ultimately the brain controls what we eat, so when control breaks down, this is a brain problem.

Question 8

What are some chronic illnesses caused by obesity?

Answer 8

Type II diabetes, circulatory disease, joint damage, cancer.

Question 9

What defines an eating disorder?

Answer 9

An internalising disorder exhibiting severe & persistent disturbance in eating behaviours, with associated distressing thoughts & emotions.

Question 10

Name the eating disorders…

Answer 10

BINGE EATING - repeated binge, no compensation

ANOREXIA NERVOSA (AN) - dietary restriction and/or purging. Intense fear of weight gain, body image disturbance

BULIMIA NERVOSA (BN) - binge eating with compensation

MUSCLE DYSMORPHIA - body dysmorphic sub-class. more men concerned with small body/muscle

ORTHOREXIA NERVOSA - not formally recognised but obsession with ‘healthy/proper/clean’ eating

Question 11

STARVATION - not enough to eat, mainly affects immune system. Consider broader idea of non-privileged V privileged/choice V no choice…

Answer 11

Scientists conclusion that eating is mindless…? consider politics, advertising, position, culture…….