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203 - Theme 1 - The Endocrine System > L11 - Appetite and weight > Flashcards

L11 - Appetite and weight Flashcards

1
Q

Definitions of obesity

A

A personal failing
-lack of self-discipline

A medical problem
-Aetiology
=>genetic
=>environmental

A neurobehavioral hereditary disorder heavily influenced by the environment

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2
Q

Definition of homeostasis

A

Precise matching of energy intake and energy expenditure

  • average decade of adult life
  • approx 10 million kcal consumes
  • tendency towards slight average weight gain
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3
Q

Measurements used

A

BMI

Waist circumference

Skin-fold thicknesses

Bioelectric impedance analysis

Ethnicity specific cut-offs

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4
Q

BMI ranges

A

< 18.5 underweight

18.5-24.9 normal

25-29.9 overweight

30-39.9 obese

> /= 40 morbid obesity

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5
Q

Obesity in England

A

2010-2013: prevalence of obesity in England stabilised at 25%

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6
Q

Medical problems associated with obesity

A

30,000 (6%) UK deaths attributable to obesity

  • metabolic syndrome /type 2 diabetes
  • cardiovascular disease
  • respiratory disease
  • liver disease
  • cancer
  • reproductive dysfunction
  • joint problems
  • psychological morbidity
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7
Q

Co-morbidities and obesity

A

the higher the BMI, the higher the rusk of patients that have 3 or more co-morbidities

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8
Q

In what range of BMI do health risks start?

A

In the overweight BMI range

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9
Q

What is metabolic syndrome?

A

Constellation of closely associated CV risk factors

  • visceral obesity
  • dyslipidaemia
  • hyperglycaemia
  • hypertension

Insulin resistance is the underlying pathophysiological mechanism

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10
Q

BMI vs body fat distribution

A

central vs peripheral

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11
Q

What is metabolic syndrome associated with?

A

Central (visceral) fat

Body mass index >30

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12
Q

Type 2 DM: risk determined by?

A

age

obesity

family history

ethnicity

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13
Q

Type 2 DM: targets

A

rich in poor countries

poor in rich countries

*source of socioeconomic inequality in health

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14
Q

Type 2 DM: increased prevalence in?

A

ageing population

obesity
-T2 DM younger

increased detection/diagnosis
-50% cases T2 DM picked up on routine examination

increased survival with T2 DM

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15
Q

CV disease

A

‘Metabolic syndrome’ PLUS

^blood vol and blood viscosity

^vascular resistance

^hypertension

^left ventricular hypertrophy

^coronary artery disease

^stroke

  • ^=increased
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16
Q

Respiratory system problems caused by obesity

A

obstructive sleep apnoea

hypoxia/hypercapnia

pulmonary hypertension
-RH failure

accidents
-daytime somnolence

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17
Q

GI/Liver problems caused by obesity

A

Non-alcoholic fatty liver

Non-alcoholic steatohepatitis

May progress to cirrhosis, portal hypertension, hepatocellular cancer

Gallstones

Reflux

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18
Q

Cancers caused by obesity

A

Approx 10% of cancer deaths in non-smokers attributable to obesity

Types of cancer include:
-breast, endometrial, oesophagus, colon, gall bladder, renal, thyroid

Mechanisms include:
-increases insulin, increased free IGF-1, increased oestrogen, dip-cytokines, reflux

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19
Q

Reproductive system problems caused by obesity

A

Polycystic ovarian syndrome

  • oligomenorrhoea, hirsutism, acne
  • subfertility
  • endometrial hyperplasia
  • insulin resistance

Male hypogonadism

Adverse pregnancy outcomes

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20
Q

Joint problems caused by obesity

A

Osteoarthritis

Gout

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21
Q

Psychological problems caused by obesity

A

Depression

Eating disorders

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22
Q

Aetiology of obesity: GENETICS => rare

A

Obesity associated syndromes

  • Prader-Willi
  • Bardet-Biedl
23
Q

Aetiology of obesity: GENETICS => common

A

polygenic

susceptibility genes

heritability of weight
heritability of height

24
Q

Aetiology of obesity: GENETICS => other causes

A

Hypothyroidism

Cushing’s syndrome

25
Q

Aetiology of obesity: ENVIRONMENT => diet

A

high fat

high sugar

‘coca-colinisation’ of developing world

socio-economic factors

26
Q

Aetiology of obesity: ENVIRONMENT => physical activity

A

20-25% total energy expenditure

obesity prevalence related to proxy measures of physical activity

  • car ownership
  • TV viewing

socio-economic factors

27
Q

Aetiology of obesity: foetal programming

A

‘Programming’:stimuli/insults at critical periods have persistent biological effects

Stressors in utero

  • ?udnernutrition, ?trace elements, ?other
  • crudely represented by birth weight

Mechanism: epigenetic modification of gene expression

Example:

  • ‘programmed’ adrenal axis overactivity in adulthood
  • causal factor for metabolic syndrome
  • increased vulnerability to CHD
28
Q

Life course model

A

Factors operating at every stage of life affect health outcomes later in life

Pathway of risk between events and health outcomes

Worst outcome associated with:

  • low birth weight
  • excessive weight gain in infancy/childhood
  • adult obesity
29
Q

Aetiology of obesity: Gut Microbiome

A

Differences in gut bacteria
-can be induced by diet e.g. high fat diet

Transplantation of faecal material alters insulin sensitivity

The gut micriobiome is influenced by diet and influences disease risk, it is integral to host homeostasis as well

30
Q

Regulation of appetite and weight: slow-acting hormones

A

regulate body weight

Leptin

Insulin

Signal % body fat to hypothalamus

  • decreases food intake
  • increases energy expenditure
31
Q

Regulation of appetite and weight: rapid-acting peptides

A

regulate meal sizes

released from GI tract

  • cholecystokinin (CCK) decreases eating
  • ghrelin increases eating
  • PYY decreases eating up to 12hrs

act via hypothalamus

32
Q

Regulation of appetite and weight: leptin (mice)

A

ob/ob mouse
-leptin deficient

db/db mouse
-mutation of leptin receptor

ob gene product = leptin

leptin treatment reduces obesity in ob/ob mouse

33
Q

Regulation of appetite and weight: leptin (humans)

A

Starvation signal

Permissive effect on puberty/reproduction

Obese humans
Very rare:
-leptin deficiency
-mutation of leptin receptor
Usually:
-^ [leptin] with ^ fat
-?'leptin resistant'?
-?decreased CNS leptin transport
34
Q

Treatment: lifestyle modification => diet

A

500-1000kcal energy deficiency

Low energy density

  • decrease sat fat, sugar
  • increase fruit & veg (sub for other foods)

Decrease portion sizes, snacking

Structured meals/meal replacements may help promote greater weight loss

35
Q

Treatment: lifestyle modification => physical activity

A

Exercise 7 days a week

  • 30 mins moderate-high intensity OR
  • 60 mins low intensity

Target 10,000 steps/day
-^ 500 step increments

Regardless of weight/weight loss, exercise increases health

36
Q

VLCD and T2 DM: principle

A

primary care programme

patients with T2DM diagnosis < 6 years prior

VLCD (830 kcal/day) for 3-5 months

  • initially, total diet replacement with formulae
  • then stepped food reintroduction (2-8 weeks)
  • long-term maintenance with structured support
37
Q

VLCD and T2 DM: outcomes

A

12 month outcomes reported

24% of patients achieved 15kg weight loss or more

46% induced remission of T2DM
-normal HbA1c off all medication for 2 months

> 10kg weight loss: 73% remission

38
Q

Lifestyle modification: usual targets

A

10% weight loss

1-2 lb (0.5-1kg) per week

some evidence that ambitious goals promote more weight loss

39
Q

Lifestyle modification: problems

A

most patients can achieve approx 5-10% weight loss/1 year

yo-yo dieting/regaining weight loss

obesogenic environment

weight loss results in increased hunger, reduced satiety and decreased metabolic rate

40
Q

Lifestyle modification: best hope

A

sustainable lifestyle changes

diet combines with exercise/physical activity

ongoing management is required to maintain weight loss

41
Q

Treatment: pharmacological therapy => the past

A

25 years research

123 products

1 currently licensed = orlistat

42
Q

Treatment: pharmacological therapy => ORLISTAT mechanism

A

binds and inhibits lipases in the lumen of the gut

prevents the hydrolysis of dietary fat into absorbable free fatty acids/glycerol

excrete approx 1/3 dietary fat

43
Q

Treatment: pharmacological therapy => ORLISTAT adverse effects

A

flatulence, oily faecal leakage, diarrhoea

reduced absorption of fat soluble vitamins

  • ADEK
  • supplement
44
Q

Treatment: pharmacological therapy => METFORMIN

A

best 1st line agent for over-weight/obese patients with T2DM

all other oral hypoglycaemic agents and insulin cause weight gain

used in diabetes prevention trials but not licensed for this use

recommended by NICE for prevention of T2DM in adults at high risk

45
Q

Treatment: pharmacological therapy => problems

A

can only increase by 3-4 fold the proportion of patients who achieve 5% weight loss in a year

weight re-gain after treatment stopped

46
Q

Treatment: pharmacological therapy => future

A

all identified gut peptides/neuropeptides/their receptors are potential therapeutic targets/options
-gut hormones in combination most likely way forwards

47
Q

Surgical treatment: laparoscopic adjustable banding

A

restrictive only

inject/withdraw saline to adjust the diameter of the band

48
Q

Surgical treatment: Roux-en-Y gastric bypass

A

restrictive

malabsorptive

alterations in gut hormones and bile acid flow contribute to weight loss

micronutrient deficiencies
-supplement with iron, B12, folate, calcium, vit D

Dumping syndrome
-GI & vasomotor symptoms

49
Q

Surgical treatment: Roux-en-Y gastric bypass effects

A

endocrine factors important in effects

  • plasma from operated rats to sham-operated rats
  • ate 1/3 less

increased satiety seems to be key
-F-MRI studies

50
Q

Advantages of surgical treatment

A

weight loss 25-30%

resolve or improve co-morbidities
-brings cost savings

51
Q

Disadvantages of surgical treatment

A

preoperative mortality/morbidity
-depends on procedure and experience of surgeon

long-term follow up
-micronutrient deficiencies

some weight re-gain
-patients will still be obese

expense
-through cost effective by 2-5 years, depending on co-morbidties and weight

52
Q

UK position bariatric surgery: NICE guidelines

A 
NICE 2006
-after failure of other options if
-BMI > 40 kg/m-2
-BMI > 35 with co-morbid conditions
Or first line
BMI > 50 kg/m-2

NICE 2014

  • recent onset T2DM:
  • expedite bariatric surgery if BMI>35
  • consider surgery if BMI>30
53
Q

UK Position bariatric surgery:

NHS guidelines

A

NHS England 2013
As per NICE but…..
Must have been obese for at least 5 years
Must engage with non-surgical weight-loss programme for 12-24 months first

54
Q

Public health/societal

A

Schools
-PE, lunches, vending machines

Urban design

Marketing/media/social media
-food labelling, food ads

203 - Theme 1 - The Endocrine System (11 decks)

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