hunger eating and health

Question 1

evolution and digestive system

Answer 1

evolutionary to make the most from the food that we eat → extraction of nutrients effectively

Question 2

digestive system
* mouth and salivary glands
* oesophagus
* stomach

Answer 2

mouth and salivary glands
* mastication and saliva (alkaline)
* break down food

oesophagus
* transport to stomach
* alkaline conditions - acid from stomach can damage this

stomach
* churning and break down of food
* acid digestive enzymes

Question 3

digestive system -
* liver / gall bladder
* pancreas
* small intestine
* large intestine

Answer 3

liver / gall bladder
* digestive enzymes added into small intestine

pancreas
* produces insulin and glucagon to store and release energy

small intestine
* absorbs nutrients from food (majority)

large intestine
* removes water and packs waste

Question 4

digestive system
* liver and kidneys
* rectum/anus and bladder

Answer 4

liver and kidneys
* filter out toxins for excretion

rectum/anus and bladder
* store and expel waste

Question 5

pancreatic hormones (2)

Answer 5

insulin
* carbs from blood into storage - fast release energy
* carbs (glucose) → glycogen, proteins

glucagon
* fuel from storage to blood
* glycogen and proteins → carbs (glucose)
* frees fat stores (fatty acids) - use as fuel when glucose stores are low
* carb → fat → protein = order of fuel release

diabetes have issues with either of these hormones - with store or release

Question 6

human complex food intake - macros

Answer 6

omnivorous - so need the range of foods

macro nutrients:
fruit and veg
carbs
dairy
protein
fats

eating macros will mean we get all necessary micros

variation between (number of stomachs) and within species (dairy tolerance)

Question 7

product and storage mechanisms: lipids and fats

Answer 7

stored as fats

largest and most efficient energy store

not quick release energy like carbs

Question 8

product and storage mechanisms: amino acids

Answer 8

stored as protein

mostly in form of muscle tissue

Question 9

product and storage mechanisms: glucose

Answer 9

stored as glycogen

in muscles and liver

fast release energy

Question 10

product and storage mechanisms: micros (vits and mins)

Answer 10

body structure

bones, cell structure etc.

get these from eating a balanced diet

Question 11

mechanisms to ensure needs are met

Answer 11

evolutionary → developed to balance intake and output
hunger and craving to make you eat specifically

homeostasis → when set point is violated

fat metabolism will change to push up or down to the set point

signalling:
* brain → sensitive to glucose shortages, hypothalamic regulatory nuclei
* liver → sensitive to shortage of glucose and lipids
* stomach → signals to brain (grehlin release) to communicate need for food if it is unstimulated

example = running low:
* hunger (motivational state) - from low fatty acid and glucose levels
* cravings (automatic behavioural state)
body correction for this:
* release of glucose
* take in more food

Question 12

where eating optimum goes wrong

Answer 12

internal factors - learning, emotions
environmental - toxic environment

Question 13

satiety - short term signals from body (5)

Answer 13

adequate glucose and lipid acid levels
detected in the brain and liver - therefore stop eating

stomach distension
can also feel from anxiety

buccal activity
lots of chewing

high levels of sensory stimulation
big on taste and smell

appetite suppressant chemicals
e.g., caffeine, amphetamines

Question 14

satiety - use in diet medications

Answer 14

try to offset adequate glucose and lipid intake by stimulating the other signals (don’t work long term) - limited temporary success

Question 15

is there a satiety brain centre

Answer 15

previously thought in the hypothalamus (or other areas depending on different studies

recent evidence = no centre

more hormonally controlled
- ghrelin, neuropeptide Y, serotonin

Question 16

long-term feedback mechanism of fullness

Answer 16

fat releases leptin

increases metabolic rate
decreases food intake

desensitises brain to hunger signals

inhibits effect of other hormones that drives eating (particularly neuropeptide Y)

Question 17

satiety cascade

Answer 17

sensory
→ early signals saying you have had enough food, sensation of fullness, chewing food

cognitive
→ know you’ve already eaten a lot

post-ingestive
→ food hasn’t been absorbed but you know to not eat more

post-absorptive
→ signals from absorption of food to stop eating

this is why gum doesn’t work long term as you don’t feel full after chewing

Question 18

ghrelin vs leptin

Answer 18

leptin = from fat
stops intake of food - satiety

ghrelin = released by stomach
from hunger - stimulates eating

Question 19

health implications of normative poor eating - Dutch hunger winter (1940)

Answer 19

study of victims of hunger winter where there were no supplies

Question 20

health implications of normative poor eating - minnesota starvation experiment

Answer 20

people either had to join the army or take part in starvation experiment (coercion…)

studied effects of starvation on 35 men:
* cognitive, social, emotional effects of starvation and weight gain
* gaunt, extremities filled with fluid, dizziness, depression, lack of energy, became food obsessed, more irritable
* rehab after experiment was difficult → weight continued to drop even with more food - kept feeling hungry
* some took 2 years to recover physically and mentally after the 6 months of eating 1800 kcal a day

base understanding of anorexia on these studies - the lack of food fuels the obsession as well as the mental disorder itself

Question 21

starvation effects

Answer 21

nutritional deficits - scurvy, rickets etc.

starvation effects can be immediate, long-term or both:

concentration/cognitive
social
physical and mental development
emotional instability (tryptophan cycle)
all physical systems

starvation effects can cross generations
* obesity in children of starved mothers - limited availability of nutrients in early environment from breast milk

Question 22

effects of obesity

Answer 22

affects social functioning
strong link with premature mortality

related to specific problems in children:
bullying, school absence, shame, stigma, self-esteem

Question 23

factors that take body away from homeostasis (6)

Answer 23

genetics
learning
social learning
environmental factors
social pressures
food industry
toxic environment

Question 24

factors that take body away from homeostasis - genetics

Answer 24

more likely to eat particular foods

learn other tastes but they take longer - grown-up tastes e.g. olives, acid foods, broccoli

predisposed to like high-energy, high-tase foods - sweet, fatty, and salty - more likely to contain nutrients

less likely to enjoy bitter foods - association with toxicity

Question 25

factors that take body away from homeostasis - learning

Answer 25

culture → common foods in some are not in others

upbringing → food experienced early tend to be more readily approached

satiety to specific foods → don’t want to eat same foods multiple times in a row, keeps diet varied

Question 26

factors that take body away from homeostasis - social learning

Answer 26

influenced by what is going on around you

imitation of what and how others eat

types of food, speed and amount of eating

powerful cultural influence - eat what you perceive as normal/local/customary

Question 27

factors that take body away from homeostasis - environmental factors

Answer 27

lighting - eat more in dim light

temperature - eat more when cold than hot

portion sizes - what is portrayed as normal

smells - of food and environment

location and proximity of food

Question 28

factors that take body away from homeostasis - agriculture and food industry

Answer 28

food industry goes through stages in level of positive/toxic influence

purpose = ensure we aren’t starved due to increasing population → Malthusian hypothesis (predicts human race would starve as we cannot produce enough food to fuel population - disproven in most countries)

currently toxic:
* selling ultra-processed foods for cheap
* large quantities, ensures profit margins, fatty and sugary foods
* puts premium prices on more healthy foods - fruit and veg often out of season and so costs them more

Question 29

factors that take body away from homeostasis - agriculture and food industry as toxic example

Answer 29

Nixon in 1970s subsidised growth of corn

high fructose corn syrup became huge product in US due to high levels of corn

sold cheaply and used in everything instead of sugar

increases risk of fatty liver disease, decreased insulin sensitivity, precursor for gout, obesity levels

HFCS doesn’t give you same energy as sugar does - leads to overconsumption

Question 30

factors that take body away from homeostasis - toxic environment example - supersize me

Answer 30

man ate three meals per day at McDonalds - supersized if it was offered to him

in 30 days gained 11kg, high cholesterol, mood swings, fatty liver

Question 31

factors that take body away from homeostasis - toxic environment

Answer 31

describes how human evolution and environment we are in now are at odds
* food scarce cultures - obesity is a status symbol
* food plentiful cultures - obesity is stigmatised as sign of weakness

evolved to get food where you can - high-energy food only seasonally available so eat high-fat/salt/sugar foods where you can - to build up fat stores

past 50-60 years - environment change pushed us to obesity risk, easy to access food, food industry puts lots of sugar/fat/salt into food → cheaper and more palatable
* liquid calories too

lack of exercise - screen time - advertising for food and drink → dissociative effects, reduces self-control

intergenerational effects of this seen