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B-Med > Obesity/Diet > Flashcards

Obesity/Diet Flashcards

1
Q

Prevalence of obesity

A

From Health survey for England (HSE) and National child Measurement Programme (NCMP) as official national statistics
2014: 58% womrn, 65% men overweight/obese
26% overall obese
Almost doubled since 1993

2014/2015:
1in5 children in reception overweight/obese
1in3 children in year 6 overweight or obese

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2
Q

WHO definition

A

Overweight and obesity are defined as abnormal or excessive fat accumulation that may impair health

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3
Q

Measuring Obesity:
BMI

Limitations of using BMI

A

weight in kg/height in m2

underweight: <18.5
Normal: 18.5-24.9
Overweight: 25-29.9
Obese: >30
Severe (morbid) obesity: >40

Limitations:

  • no acknowledged difference in fat and muscle
  • No acknowledgement of fat placement
  • Doesnt account for ethnic difference - south asians have incr risk of weight related diseases at lower weight
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4
Q

UCL study on self-perception of obesity

Johnson et al 2014

A

2 surveys 5 years apart (2007+2012)

Results showed very few obese people described themselves as obese
women ~12%
Men <10%

There was awareness that stigmatisation may go with the term obese, so also looked at “very overweight” however still very few identified in this category, even fewer women

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5
Q

Black et al. 2015

parents estimating children’s BMI

A

Looked at children aged 4-5 and 10-11, asked parents to determine BMI

results showed that 1/3 parents underestimated BMI

NB:Overweight children at increased risk of premature mortality and obesity-related disease in adulthood

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6
Q

Jackson et al 2015

adolescents perceptions of their own weight

A

Looked at adolescents aged 13-15 from annual health survey for england between 2005&2012

asked if they thought they were too light/heavy/just right and also weighed & measured

Results: very few normal weight teens thought they were overweight but overweight teens didnt aknowledge - 39% of overweight teens said they were just right

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7
Q

Measuring Obesity:

Waist Circumference

A

Men: overweight = >37in
obese >40in

Women: >32in
obese:>35in
(ethinic specific values have been defined)

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8
Q

Measuring Obesity:

Waist to height ratio

Ashwell et al 2012

A

Waist should be <1/2 height
meta-analysis of 31 studies, over 30,000 people in different ethnic groups showed this was better than WC & BMI for detecting cardiometabolic risk factors

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9
Q

Measuring Obesity:

% body fat - calipers

Bodystat + Tanita

A

inches of fat in area /height x 27 = body fat %

1st height, weight, age & gender is noted
A small electrical current is circulated, resistance to the current by fat and muscle is measured

resistance depends on fat and muscle as muscle holds more water than fat so current moves through the body with less resistance

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10
Q

Hydrostatic body fat testing

BodPod

A

considered to be gold standard
expensive & uncomfortable
person must empty their lungs as much as possible, then put in tub and must hold their breath

BodPod:
Also considered gold standard
expensive
equally accurate to hydrostatic
uses air displacement plethymography to detect small changes between fat and lean body mass ie bone muscle organs
person sits in pod for 2-3 mins and volume of air displaced by the body is measured and body fat % calculated

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11
Q

Health Consequences of Obesity

European investigation into cancer & nutrition

A

Studied relative risk of death among men and women according to BMI & WC, adjusted for age, smoking status, educational level, alcohol consumption, physical activity & height

showed famous J shaped association - normal BMI/WC hits the line of relative risk, then higher rate is found in those with high/low body fat

showed that WC & BMI useful for predicting death

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12
Q

CVD & obesity

Smolina et al 2002

A

CVD = leading cause of death worldwide
WHO: 30% of worldwide deaths every year

mortality from CVD in the UK has been falling since 1970s - DR from MI have halved since 2002

Smolina et al believe drop due to:
decr smoking
incr hospital treatment
incr management of BP & choelsterol

massive cost to UK
To NHS- £8.7bill
to economy - £19bill

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13
Q

Diabetes & CVD

complications

micro/macrovascular

A

Obesity is leading caus of T2D

diabetes is incr in prevalence globally & in UK

382million adults have T2D
around 45% sufferers dont know they have it
10% of NHS budget

Complications:

  • Chronic hyperglycaemia caused by diabetes linked with long-term damage, dysfunction & failure of various organs
  • Harmful effects divided into microvascular & macrovascular complications

microvascular:
retinopathy- damage to the eye, biggest cause of blindness

nephropathy-damage to kidneys, can lead to kidney failure

neuropathy - can lead to foot ulcers, biggest cause of amputation

macrovascular:
Stroke
CHD
Peripheral vascular disease

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14
Q

Obesity & cancer

A

Link beteen weight and cancer is firmly established (Guh 2009)

meta-analysis of 89 studies:
-overweight & obesity was assoc with incr risk of Breast, colorectal, endometrial, kidney & ovarian Ca

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15
Q

Other consequences of obesity

A

asthma
gallbladder disease
osteoarthritis
chronic back pain

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16
Q

Adipose tissue as an endocrine organ

A

Most important to take intra-abdominal fat into account when considering obesity

white adipose tissue is highly complex:
composed of various cell types that interact dynamically with each other through secretory factors called adipoteins including:
hormones
cytokines
chemokines

abdominal fat releases adipoteins into the circulation

adipoteins are associated with:
IR
dyslipidoemia
incr LDL cholesterol
Triglycerides
decr HDL cholesterol
incr BP
17
Q

Diet:

foods linked with ill health

A

saturated trans fat
salt
sugar
red meat

18
Q

Diet:

foods linked to good health

A 
strong assoc for red CVD:
antioxidants vit C
vegetables
Nuts
Mediterranean diet
mod evidence for protective effect:
fruit
fish
wholegrains
fibre
19
Q

Diet & CVD

A

high sodium diet increases risk of hypertension which is a CVD risk factor

strong evidence that trans fats contribute to CVD through atherosclerosis

20
Q

Emotional consequences of obesity

YOUNG

A

body dissatisfaction

slightly lower self-esteem in community samples

higher rates of depression in clinical populations

discrimination & social exclusion - incr bullying & teasing at school, decr college attendance
-teachers rated ability of obese girls lower

21
Q

Emotional consequences of obesity

ADULT

A

body dissatisfaction

higher rates of depression with higher grade of obesity

less likely to get married

employment: employers less willing to hire obese people, obese people earn less, less likely to get a promotion

22
Q

Fat Shaming

A

Jackson et al 2014 - 2994 people
<1% of normal weight people reported weight discrimination compared to 36% of morbidly obese people

those who reported weight discrimination gained an average of 0.95kg iver the 4 year stufy period

23
Q

what causes obesity?

GENETICS

A

two ways to study genetic link to obesity: quantitave i.e. twin studies or molecular (GWAS)

Twin studies: modelled that weight is heritable

GWAS: Found 31 common genetic variants identified as indices for adiposity

identifying SNPs that are related to body weight

but only account for <3% of variation in BMI of both adults & children ==> missing heritability problem

24
Q

what causes obesity?

OBESOGENIC ENVIRONMENT

A 
the environment we live in makes obesity easy:
food environment:
-portion sizes
-cost
-availability
-high fat
-low fibre (therefore food not filling)
-food advertising

Activity environment:

  • high cost of activity (gym membership)
  • labour saving devices e.g. dishwasher
  • sedentary travel (tube>cycle)
  • enjoyable sedentary past times e.g. netflix
  • high ambient temperature
25
Q

Psychology of eating

A

biological basis - we have hunger as a biological survival mechanism

we are born with a preference for sweet foods and dislike bitter foods - evolutionary

psychology:
we eat for other reasons than hunger e.g learned associations and preferances, cognitions, hedogenic reasons (it is enjoyable), environmental and social factors

26
Q

Models of Eating Behaviour

THE DEVELOPMENTAL MODEL

A
  • emphasis is on learning
  • exposure
  • more likely to enjoy foods you are exposed to, includes foods seen on social media or eaten by friends etc
  • Research suggests 8-10 exposures are required to significantly change preferences
27
Q

Models of Eating Behaviour

SOCIAL LEARNING

A

Importance of modelling and observation
seeing older sibling eat something the younger child is more likely to eat it
-parental feeding has an effect on kids - they control what is in the house
-interesting association between mother’s ‘health motivation’ and the quality of children’s diet however studies have shown that dieting paretns feed their children more of what they are denying themselves

28
Q

Models of Eating Behaviour

SOCIAL LEARNING
ASSOCIATIONS

A
  • seeing food as a reward e.g. if you eat your veg you get dessert) increases child preference for the treat

overt & covert food control has an effect
overt: firm rules about what child can/cannot eat
covert: simply not buying unhealthy food
> showed overty were more likely to eat the unhealthy foods than covert

29
Q

Models of Eating Behaviour

COGNITVIE MODEL OF EATING BEHAVIOUR

A

TPB: intention-behaviour gap
shown that attitude is assoc to fat intake, salt use and fast food eating

attitude is complicated as it can be both pos and neg e.g. tasty but fattening

PBC assoc with the eating behaviour to lose weight & eat healthily

social norms show no assoc with eating behaviour

30
Q

Weight Concern & body dissatisfaction

A

-Emphasis is on the meaning of food and weight
Food can mean:
comfort, boredom, pleasure, celebration, treat, family, religion etc

meaning of food & weight:
attractiveness, control & success

31
Q

BODY DISSATISFACTION

A

higher in females

most women & girls want to be thinner

conceptualised as a discrepency between actual size and ideal, negative emotions regarding body size & shape

32
Q

Dieting & overeating

A

body dissatisfaction is linked to both dieting and over-eating

dieting shows restraint theory

dieting can lead to motivational collapse causing overeating

dieting can lead to overeating when feeling low

33
Q

APPETITE & ADIPOSITY

A

assoc b/ incr appetite & incr adiposity

twin studies have shown that appetite is highly heritable

34
Q

Treating obesity

Government policy

A

DOH policy focuses on reducing obesity, improving diet, giving children a healthy start - milk/free fruit at school/balanced school dinners

35
Q

Treating obesity

lifestyle interventions:

Galani & Schneider 2007

A

multi-factorial interventions tailored to the patients need and risk factor status, include:

  • promoting healthy lifestyle habits
  • physical exercise training

Galani & Schneider 2007 meta-analysis of 17 interventions resulted in significant weight loss on average participants lost 3.5kg

36
Q

Treating Obesity:

behavioural therapy

A

advice on behaviours to modify energy balance - nutrition/exercise

stategies e.g. goal setting - SMART goals: specific, measurable, achievable, results-focused, time bound

self-monitoring of eating & activity-food/exercise diary

stimulus control in relation to food & activity choices:
avoidance/distraction/resistance

evaluation of pos & neg cognitions:
-thought diary to monitor internal emotional triggers, prevents using food for mood modifications

reward healthy behaviour but NOT WITH FOOD

37
Q

Gastric Bypass

A

Most effective method, can achieve ~26% loss in body weight

38
Q

Weight Regain & Metabolic Processes

A

Weight lss doesnt reduce no. of fat cells - it shrinks/flattens them

body compensates for weight change, tries to return to old weight:
feel less full - decr in salience of satiety signals
feel more hungry-incr in salience of hunger signals

Studies found out that weight loss of >10% is associated with a reduction in energy expenditure MACLEAN ET AL 2011

B-Med (4 decks)

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