PSY2003 W11 Hunger, Eating and Health (L) Flashcards
What makes up a toxic environment?
Very easy to eat or drink large amounts of high calorie food in modern times.
Kelly Brownell coined this term to describe the way in which human evolution and the environment that we are now in are completely at odds:
-In cultures where food is scarce, obesity is valued as a status symbol.
-In cultures where food is plentiful, obesity is stigmatized as a sign of weakness
What is involved in the human digestive system?
Mouth and salivary glands
Oesophagus
Stomach
Liver/gall bladder
Pancreas
Small intestine
Large intestine
Liver and kidneys
Rectum/anus and bladder
What does the mouth and salivary glands do?
Mastication and saliva (alkaline)
What does the oesophagus do?
Transporting food to stomach
Set up for alkaline conditions, so acid from the stomach can damage it
What does the stomach do?
Churning food and breaking it down
Acid digestive enzymes
What does the liver/gall baldder do?
additional digestive enzymes added into the small intestine
What does the pancreas do?
Produces insulin and glucagon to store and relase energy
What does the small intestines do?
Absorbs most nutrients from the food that we eat
What do the large intestines do?
Removes water and packs waste
What does the liver and kidney do?
Filter out towins for excretion
What does the ractum and anus and bladder do?
Store adn expel waste
What does insulin do as a key pancreatic hormone in the process?
Shifts carbohydrate from the blood to storage (glycogen, proteins)
What does Glucagon do as a key pancreati hormone?
Shifts fuel from storage to where it is needed to fuel the body.
Converts glycogen and proteins to carbohydrate.
Frees fat stores (free fatty acids) to use as fuel when the glucose stores are low
WHY DOES OUR INTAKE HAVE TO BE SO COMPLEX?
Because we are omnivorous. Our diet includes a range of key elements: our bodies have evolved to process them. A lot of variation between species e.g., number of stomachs. Some variation within species e.g., dairy tolerance
What are the 3 core rpoducts ?
Lipids/Fats
Amino acids
Glucose
(+minurals and vitamines)
How are lipids/fats stored?
Fats – largest and most efficient energy store
How are amino acids stored?
Proteins – mostly in the form of muscle tissue
How is glucose stored?
Glycogen – stored in muscles and liver, fast release
How does mineral and vitamines are stored?
Body structure – bones, cell structure ect
How do we ensure that those needs are met?
Homeostasis/set point theory
Hunger
Craving
And why does it all go wrong sometimes?
Internal factors (e.g., learning, emotions)
Environmental factors (the ‘toxic environment’)
What are some mechanism for eating?
Evolutionary terms: body developed the ability to balance our intake and output. Homeostasis kicks in when our body’s set point is violated. going over or below the set point: fat metabolism will change to push it up or down. Body tried to stay in a particular zone.
How do we know when we are running low on certain foods?
Detectors in our body tell us when we are running low on nutrients/fuel, and trigger our biology and behaviour
Brain is sensitive to shortage of glucose (hypothalamic regulatory nuclei)
Liver is sensitive to shortages of both glucose and lipids
Stomach sends signals to the brain (release of ghrelin) re need for food if it is unstimulated
What is homeostasis and set point thoery?
When we are running low on fuel, we experience:
Hunger (a motivational state)
due to low levels of fatty acids/glucose
craving (a more automatic behavioural state)
The body corrects by:
releasing glucose (see above)
taking in more food
Why do we stop eating?
The body generates a range of short-term satiety signals:
Adequate glucose and lipid acid levels: detected in the brain and liver.
Stomach distension
Buccal activity: lots of chewing
High levels of sensory stimulation: big on taste and smell
Appetite suppressant chemicals: e.g., caffeine, amphetamines
Most diet products try to offset the first with the others (with very limited and very temporary success)
Is there a centre for satiety?
Previous research/theory suggest that there was a centre in the brain for satiety (hypothalamus), more recent studies suggest no centre. Instead, it looks as if the process is more hormonally controlled: e.g., ghrelin, neuropeptide Y, serotonin. A long-term feedback mechanism to attend to. Fat tissues secrete a hormone – leptin
What is leptin’s two affects?
Increases body metabolic rate
Decreases food intake in two ways: desensitizes the brain to hunger signals and inhibits the effect of other hormones that drive eating, particularly Neuropeptide Y
What is the satiety cascade?
Food > sensory > cognitive > post-ingestive > post absorptive
What is homeostasis?
Homeostasis is how the body ensures that we meet our needs: when we are hungry, we eat, when we are sated, we stop eating. Everyone’s eating should be pretty balanced: no overeating, undereating, or inappropriate weight. Unfortunately, a little too simple…
Hunger =/= Satiety
Why are there difficulites with the balance sometimes?
Homeostasis is a baseline for explaining eating behaviours. There are multiple factors that we need to understand. It mattters becuase of the health implications of normative poor eating
What are the health implication of poor eating?
Dutch hunger winter 1940
Horrible winter with no supplies
Victims of hunger winter studied
What are the health implication of poor eating?
Minnesota starvation experiment (Keys et al 1950)
Join the army or take part in a starvation experiment (concerns around coercion). Studied the effects of starvation on 35 men. Cognitive, socially, emotional effects of starvation and weight gain
What are the deficits that might come from poor eating?
Nutritional deficits e.g., scurvy; rickets; Korsakoff’s syndrome.
Starvation effects can be immediate, long-term or both: concentration/cognitive, social, physical and mental development, emotional instability (tryptophan cycle) and all physical systems.
Starvation effects can cross generations e.g., obesity in the children of starved mothers.
What are some implications of poor eating?
Obesity affects multiple systems, including social functioning. Strong link to premature mortality. Also related to specific problems in children:
-experiences of bullying
-school absence
-stigma
-self-esteem
What are some factors that take use away from homestasis?
Genetics
Learning
Social learning
Social pressures
Food industry
The ‘toxic environment’
What is a genetic/evolutionary factor?
Genetic factors make us more likely to eat particular foods. We can learn other tastes, but it takes longer: commonly referred to as ‘grown-up’ tastes (olives, acid foods, etc.).
We are predisposed to high-energy, high-taste foods in the following categories, as they are more likely to contain nutrients
* sweet
* Fatty
* Salty
We are less likely to enjoy bitter foods, as they are more likely to be associated with toxicity
What influences learned taste prrefernces adn aversions?
Culture: foods can be common in one culture but rare in another
Upbringing: foods experienced early tend to be more readily approached
Satiety to specific foods e.g., “I don’t want curry again. We just had it last night.” helps to keep our diet varied
How does social learning affect eating/hunger?
Social/observational learning means that we eat in a number of ways that are influenced by what we see going on around us. Imitation of what and how others eat:
* types of food
* specific foods
* speed of eating
* amount eaten
This can be a very powerful cultural influence: people tend to eat what they see as normal/local/customary
What are some envionmental factors?
Lighting: we eat more in dim lighting
Temperature: we eat more when cold, less when hot
Portion sizes: what is portrayed as ‘normal’?
Smells: of the food, and of the environment itself
Location/proximity of foods
How does the agriculture adn food industry affect food intake?
The food industry goes through stages in its level of positive/toxic influence. Ensuring that we were not starved due to increasing population. ( the Malthusian hypothesis). Selling processed food that is relatively cheap: in large quantities, to ensure profit margins and fatty and sugary foods
Premium prices on more ‘healthy’ foods, often out of season, which is a ‘no-no’ in marketing terms
How is High fructose corn syrup an exmaple of argriculer and food industry influences?
High fructose corn syrup (HFCS) became a huge product in the US in the 1970’s. Farmers subsidised to grow corn, but the government needed to do something with all that corn. Created a market for high fructose corn syrup. Supplied cheap for use in products (sugar in everything). Related to obesity levels.
HFCS has some unwanted side effects: fatty liver, decreased insulin sensitivity, gout precursors
What was super-size me spurlock?
2004
Aim to draw attention to only meal options at McDonalds (& other fast food outlets) at the time were high calorie foods. Regular, Medium, Large & “Supersize” Options (advertising push by McDonalds).
If staff offered it, he had to take the ‘Super Size’ option. In 30 days, he gained 11kg, had scary cholesterol, mood swings, liver problems. The liver effects were most surprising. Significant negative publicity. Supersize option was withdrawn and salads, wraps and fruit introduced
Although, it drew a spotlight to marketing large portions and introducing greater within-restaurant choice.
It was subsequently revealed Spurlock had a significant alcohol problem which may have also contributed to the liver function issues documented in the film.
