Why do we gain weight?- Lecture 3

Question 1

NHS (2016)

Obesity rates

Answer 1

62% of adults in UK are overweight or obese

Question 2

Most at risk

Answer 2

Dieters
Students
Low SES indiv.
Shift workers

Question 3

Dieters and weight gain

-physiological explanation

Answer 3

-dieting is period of starvation so increases fat storage and food cravings
-Reductions in leptin (hormone produced by fat that inhibits hunger) and insulin
-Increase of ghrelin (associated with increased hunger)
Increased food salience and desire to binge eat

Question 4

Dieters and weight gain

-psychological explanation

Answer 4

• disconnect with internal signals of hunger and fullness
• stop listening to internal bodily signals likely to rely more on external cues
• relying on external cues in an obesogenic environment can lead to excess food intake

Question 5

Shift workers and weight gain evidence…

Answer 5

Sun et al. (2017)- meta analysis- shift workers 29% more likely to be obese

Question 6

Shift workers and weight gain

-Physiological explanation

Answer 6

FAT ABSORPTION

• Disruption of circadian rhythm may influence digestion
• Protein NFIL3 in gut during day is disrupted and can malfunction
• when mice sleep in day less NFIL3 produced so gain weight

METABOLISM

• circadian rhythm also influence metabolic rate
• shift patterns have slower metabolisms (around 8% less) – (Buxton et al., 2018)
• Insulin levels also drop- lead to cravings for sweet energy dense products

Question 7

Shift workers and weight gain

-Psychological explanation

Answer 7

Tend to increase snack food consumption (Gifkin et al., 2018)- often only food available

• Increased evidence of depression & stress (Driesen et al., 2010)
• Greater levels of emotional eating and other bad coping strategies- e.g. smoking, alcohol abuse, reduced exercise

Question 8

Low SES and weight gain

Answer 8

In past- social disadvantage used to be associated with undernourishment- swapped around in 1970s (Ban et al., 2018)

TYPE OF FOOD AVAILABLE

• Freedman & Bell (2009)- due to food outlets in certain areas- density of fast food outlets is higher in deprived areas
• evidence linking food outlets to obesity is correlational and weak (Cobb et al., 2015)

Question 9

Wansink, Painter & North (2005)

Answer 9

Self Filling Bowls- People use the bowl as cue for how much to eat
-73% more eaten in one condition but felt equally
-Fullness determined by how much people ‘believed’ they had eaten
Findings have been replicated (Brunstrom et al., 2012)
EXTERNAL CUES POWERFUL

Question 10

Low SES and the Insurance Hypothesis

Physiological Explanation

Answer 10

When we think availability of food is not certain- most species seek to store resources (Nettle, 2017)
->humans respond in similar manner - Nettle et al. (2018); Sim et al. (2018)

Question 11

Nettle (2017) (Insurance Hypothesis)

Answer 11

suggests that because females can become infertile when undernourished, they are more likely to store food during times of uncertainty

Question 12

Insurance Hypothesis Evidence:
Nettle (2018) study
Sim et al (2018) study

Answer 12

-food insecure individuals ate more in a taste test
And moderated by childhood experience of food insecurity

-manipulated how deprived people felt by asking them to imagine scenarios where they were mistreated= Relative deprivation predicted intake

Question 13

Limitations of Insurance Hypothesis Evidence…

Answer 13

• Correlational
• Not tested in actual food insecure populations (e.g. food bank visitors)
• Rationers didn’t have higher rates of obesity

Question 14

Social disadvantage and coping mechanisms

Answer 14

Hemmingsson (2014) model posits that psychological and emotional distress is a fundamental link between socioeconomic disadvantage and weight gain- how we cope with these stresses such as emotional eating.
-BUT only theoretical model…

Question 15

Spinosa et al (2018)

Answer 15

Tested out Hemmingssons model ->Psychological distress and subsequent emotional eating represent a serial pathway that links lower SES with obesity

Question 16

Freshman 15

Answer 16

In first year of Uni- av. weight gain of 15 pounds (1 stone)
Due to:
1.Change in eating habits- meals higher in calories, uncertainty about nutrition
2.Late night eating- less governed body clock
3.Stress/emotional eating- lots of work
4.Drinking- social norms at uni
5.Snack eating- whats available

Question 17

What makes an Obesogenic Environment?

Answer 17

Variety
Distraction
Portion Size

Question 18

Variety

Obesogenic Environment

Answer 18

Variety stimulates appetite
Even different forms of the same flavour
Sweet and savoury most dramatic as at either ends of flavour
Even in ‘fake’ variety (Kahn & Wansink, 2004) i.e. smarties in diff colours

Question 19

Variety

Obesogenic Environment

Answer 19

Variety stimulates appetite
Even different forms of the same flavour
Sweet and savoury most dramatic as at either ends of flavour
Even in ‘fake’ variety (Kahn & Wansink, 2004) i.e. smarties in diff colours
Surrounded by highly palatable foods that are cheaper than nutririonally rich foods

Question 20

Why does variety make us eat more?

Answer 20

Sensory specific satiety- become satiated when eating the same food
New sensory properties of food leads to increased appetite
Bodies are designed for scarcity but operate in times of plenty

Question 21

Psychological explanation behind variety effects

Answer 21

Using heuristics

Decide how filling a food is by weight (Spence et al, 2014) or by volume (Keenan et al., 2015)

Question 22

Distraction

Obesogenic environment

Answer 22

Performing multiple tasks (phone, watching tv) whilst eating, increases consumption (Oldham- Cooper et al., 2011).
IMPORTANCE OF MEMORY
Bottom-less bowls (Wansink, painter & North, 2005)
Could be that we require memory to code how much we’ve eaten

Question 23

Brunstrom et al. (2012)

Answer 23

Amnesic patients find difficult to register fullness as their episodic memory is impaired- Participants who thought they had consumed the larger 500-ml portion reported significantly less hunger- perceived hunger over actual

Question 24

Portion size

Obesogenic environment

Answer 24

Applies to all types of foods and drinks, meals and affects almost everyone- bar very young
children

Question 25

Why we have large portion sized

Answer 25

Average sizes have increased in

Question 26

Why we have large portion sized

Answer 26

Average sizes have increased in restaurants, super sized meals and drinks
Especially if taught to clear our plates as children- no waste

Question 27

Wansink & Wansink (2010)

Answer 27

Portion sizes have increased over the years- evident in images of the last supper- in art throughout history
BUT- not very stringent, art is interpretation and therefore may have been manipulated by artist (SUBJECTIVE)

Question 28

Culture and portion size

Answer 28

Cross-culturally significant?- Portion size effect seen in tribes who have not been subjected to western influence
BUT-French and North Americans both have high fat and sugar diets, but Americans have much higher rates of Obesity

Question 29

Brunstrom et al. (2012)

Answer 29

The Samburu Tribe in Kenya- when given more, they consume more.

Question 30

The French Paradox

Wansink et al. (2007)

Answer 30

French= eat till no longer hungry
Americans= eat till full

Question 31

Robinson and Kersbergen (2018) DOGS

Answer 31

Dogs given larger portion sizes also eat more= portion size effect is ingrained and innate, no matter what species

Question 32

Ways of staying a healthy weight…

Answer 32

Avoid:
night shifts
diets
intake of fatty foods
variety
Large portions
Distractions whilst eating
>>>Much like a Mediterranean lifestyle

Question 33

Mediterranean lifestyle

Answer 33

Physiological explanation= foods consumed are lower in fat (veg)
Psychological = Normal sized portions, low levels of variety, distraction, stress and dieting
=== shows how a combination of healthy physiological and psychological factors helps maintain a healthy lifestyle– minimising risk factors for obesity

Question 34

Bilman, Van Kleef and Triip (2017)

Answer 34

Many many external cues that can override internal cues of hunger
Different stages of consumption that can be affected by external cues
-Consumers in affluent societies are seriously affected by cues in the direct environment in which food decisions take place- as food is often readily available
–Big link to external cues in our obesogenic environment and development of Obesity