PPS Obesity Outcomes Flashcards
What is obesity
Accumulation of fat stores to an extent that compromises health
BMI formula
Weight kg/height metres squared
below 18.5 = underweight, 25 or above = overweight, 30 or above = obese
Problems with BMI
Doesn’t allow for difference in weight between muscle and fat
Doesn’t consider location of fat
Visceral (Abdominal) fat is most harmful
Inaccurate in different ethnic groups
Less accurate in elderly with lost muscle mass.
Waist circumference
Considers location of fat
Men: Low<94cm, high 94-102cm, very high >102cm
Women: low<80cm, high 80-88cm, very high >88cm
Doesn’t take account of skeletal size
waist:hip or waist:height ratios
Complex to assess, lacks reference data and standardised measurement protocols
BMI and risk of CVD
A high body-mass index was most predictive of death from cardiovascular disease, especially in men
Link between body weight and cancer
Meta-analysis 89 prospective studies:
- Overweight and obesity associated with increased risk of breast, colorectal, endometrial, kidney, and ovarian cancers
- Association between weight and oesophageal cancer in men only
- Mixed associations for pancreatic and prostate cancer
” pathways linking obesity and ill-health
DIRECT PATHWAY
Obesity directly impacts physiology
INDIRECT PATHWAY
Obesity associated with poo health behaviours which in turn impacts health (eg smoking, eating behaviour, alcohol consumption)
Emotional consequences of obesity
Body dissatisfaction
Lower self-esteem in community samples
Higher rates of depression at the higher grades of obesity
Obesity: discrimination and social exclusion
Educational access
- Lower college attendance
- Lower teacher ratings of ability for obese girls
- Bullying and teasing at school
Marriage and social position
- Less likely to get married
- Downward socioeconomic trajectory for obese women
Employment
- Employers less willing to take obese people as employees
- Obese employees earn less and are less likely to get a promotion
Social stereotyping
- Unattractive
- Weak-willed
Causes of obesity
Are genes related to obesity?
Predicted by parental obesity
- One obese parent – 40% chance
- Two parents – 80% chance
- Healthy BMI parents - 7% chance
Twin studies
-Obesity far more similar in identical twins reared apart than in non-identical twins reared together
Adoptee studies
- Adoptee’s weight far more strongly related biological parents
What theories explain genetic vulnerability?
- Metabolic theory
- Low resting metabolic rate is heritable and is associated with weight gain - Fat cell theory
- Cell number mainly genetically determined
- Severely obese have larger and more cells
- Can increase number of cells, especially in childhood - Appetite theory
- Leptin regulates appetite
- Lack of evidence to show that obese individuals produce less leptin
‘Obesogenic environment’ as a cause of obesity
Food environment and activity environment
Food environment Availability Cost Variety Portion sizes High energy density (kcal/g) High fat Low fibre (not filling) Food advertising
Activity environment High cost of activity Labour saving devices Sedentary travel Enjoyable sedentary pastimes High ambient temperatures
MArketing and costs
Junk food targeted to children- marketing dollars spend a lot on advertising junk food to children compared to barely anything for healthy food messages
Junk food is also cheaper per calories compared to fresh fruits and vegetables
Increased portion sizes sold in US
Higher density of fast food outlets, in deprived areas
Models of eating behaviour
- Developmental model
- Cognitive model
- Weight concern and body dissatisfaction
Developmental model of eating behaviour
Emphasis on learning
Exposure
- People show neophobia but this reduces after exposure
Social learning
- Importance of modelling and observation
- Parental feeding styles and practices are important!
Association
- Food as the reward
- Food and control- overt & covert differ
Cognitive model of eating behaviour
Emphasis on beliefs and attitudes
- Framework for explaining, predicting and changing behaviour
- Many different ones most eating research uses social cognition models
- Theory of planned behaviour
Cognitive model of eating behaviour 2
Weight concern and body dissatisfaction
Emphasis on the meaning of food and weight
Body dissatisfaction
- Research on size estimation, perceptions of reality vs. ideal and negative emotions
Dieting and overeating
- Body dissatisfaction related to dieting as well as overeating!
- Dieting ->Restraint theory
- Overeating in dieters -> Motivational collapse
- Overeating in dieters ->‘What the hell effect’
- Overeating in dieters -> Mood modification
UK Tackling Obesity strategy
Improving access to weight loss programmes through Primary
care
Changes to the ‘Food Environment’
- Banning adverts for high fat, salt or sugar products on TV and online before 9pm.
- Calorie labelling in large restaurants, cafes and takeaways.
- Ending promotion of high fat, sugar or salt products in store and online.
- Consultation on ‘traffic lights’ nutritional information and calorie labelling on alcohol
Treatment options for obesity
Behavioural interventions (diet & activity)
- ‘Lifestyle interventions’
- Behavioural Therapy
Pharmacology
Surgery
- Gastric banding
- Vertical banded gastroplasty
- Gastric bypass
Meta analysis of lifestyle interventions
Analysis of 17 interventions that had a minimum observation period of 1 year
- Lifestyle interventions resulted in significant reductions in weight compared with standard care
- On average participants lose about 3.5 kg which is maintained for 3 years
Behavioural therapy for obesity
Advice on behaviours to modify energy balance -> Nutrition and Exercise advice
Strategies to increase control over energy balance behaviours
- Functional analysis of behaviour
- Goal-setting in relation to behaviour change
- Self-monitoring of eating and activity
- Stimulus control in relation to food and activity choices
- Self-reinforcement of behaviour change
- Evaluation of positive and negative cognitions
- Reward good behaviour
- Relapse prevention
What is central to obesity behaviours?
Classical conditioning
Two stimuli repeatedly paired will become linked
- Eating cookies whilst watching TV -> turning on TV triggers craving for cookies
- Goal of behavioural therapy is to identify and distinguish cues
Self monitoring
Most important component of behavioural treatment
People can underestimate calorie intake by 40-50% per day • Detailed records of • Food intake • Physical activity • Weight • Mood (positive and negative)
Reveals patterns such as calories from soft drinks -> targets for intervention in the behaviour chain
Strategies to increase control over energy balance behaviours
Stimulus control in relation to food and activity choices
1. Avoidance
E.g. environment, situation
2. Distraction
e.g. brushing teeth instead
3. Resistance
e.g. exposure to stimulus and active control -> willpower is important!
Evaluation of positive and negative cognitions
- Thought Diary- monitor internal ‘triggers’
- Stop ‘what the hell effect’ and using food for mood modification
Reward good behaviour
- Reward but not with food
Cognitive restructuring
Aim is to modify thoughts that undermine weight loss
- Typically three categories:
- The impossibility of weight loss – previous failed attempts
- Unrealistic eating and weight loss goals
- Self-criticism regarding over eating or weight gain
“ I’ve blown my diet so I might as well eat what ever I want”
versus
“I’ve over eaten today, but only by about 400 kcals. If I stop now, I can easily make up the difference by cutting back over the next couple of days”
Effectiveness of behavioural therapy
Review of studies 1996-2002
• Patients treated with a comprehensive group behavioural approach lose approximately 10.7kg (approx. 10% of initial weight) in 30 weeks of treatment
• Importantly 80% of patients who begin treatment complete it
” pathways linking obesity and ill-health
DIRECT PATHWAY
Obesity directly impacts physiology
INDIRECT PATHWAY
Obesity associated with poo health behaviours which in turn impacts health (eg smoking, eating behaviour, alcohol consumption)
