T1 L11:APPETITE AND WEIGHT Flashcards
what measures can you use to measure someone’s weight
Body mass index (BMI)
kg / m2
Waist circumference
Skin-fold thicknesses
Bioelectrical impedance analysis
what groups do we have to be careful when measuring weight
Ethnic groups
what are the 5 ranges of BMI that someone can fall into
< 18.5 underweight 18.5-24.9 normal 25-29.9 overweight 30-39.9 obese ≥40 morbid obesity
what percentage of adults are obese in England
25%
what are the health risks of obesity (3)
Metabolic syndrome / type 2 diabetes Cardiovascular disease Respiratory disease Liver disease Cancer
what BMI category can health risks start from
overweight category
Men -25
women -24
what is metabolic syndrome
Constellation of closely associated CV risk factors and T2 diabetes
what is the underlying pathophysiological mechanism
of metabolic syndrome
(there are 2, 1 of which has 2 consequences the other has examples)
(3 marks )
Insulin resistance :
Gluconeogenesis
Dyslipidaemia
Pro-inflammatory cytokines
TNF-, IL-6 (from ‘overloaded’ white adipose tissue)
what are the signs associated with metabolic syndrome
4 marks
Visceral obesity
Dyslipidaemia
Hyperglycaemia
Hypertension
what type of body fat shape is metabolic syndrome associated with? and what type of fat distribution and BMI as well?
apple shape
Central (visceral) fat
Body mass index > 30
what can adipocyte cells release that influences hormones
ADIPOCYTOKINES
what is the risk of D2
AGE
OBESITY
FAMILY HISTORY
ETHNICITY
what are the symptoms of CVD and metabolic syndrome
4 marks
increased: blood volume and blood viscosity vascular resistance hypertension left ventricular hypertrophy
what respiratory symptoms link with metabolic syndrome
4 marks
Obstructive sleep apnoea
Hypoxia / hypercapnia
Pulmonary hypertension
-ight heart failure
what can obesity do to the liver
3m
Non-alcoholic fatty liver
Non-alcoholic steatohepatitis
May progress to cirrhosis, portal hypertension, hepatocellular cancer
Gallstones
what are the types of cancer associated with obesity and what mechanisms are associated as well?
Types of cancer include
Breast, endometrial, oesophagus,
colon, gall bladder, renal, thyroid
Mechanisms include- increase in
insulin, free IGF-I, oestrogen,
adipo-cytokines, reflux
How can obesity affect the reproductive system
Polycystic ovarian syndrome
- oligomenorrhoea hirsutism, acne
- Subfertility
- Endometrial hyperplasia
- Insulin resistance
Male hypogonadism
Adverse pregnancy outcomes
what can obesity cause to the joints
Osteoarthritis
Gout
what psychological features can obesity cause
Depression
Eating disorders
what are the rare and common genetics associated with obesity
Rare :
Obesity-associated syndromes
Prader-Willi
COMMON
Polygenic
Susceptibility genes
Heritability of weight ~ heritability of height
what are the thyroid and adrenal related causes of obesity
Hypothyroidism
Cushing’s syndrome
what are the 2 main environmental features that contribute to obesity
Diet
physical activity
what type of diet leads to obesity
High fat
High sugar
what % can physical activity count for total energy expenditure
20-50% total energy expenditure
what is the SOCIAL NETWORKING: theory of obesity
Those with more obese friends tend to be obese
what is FETAL PROGRAMMING
stimuli/insults at critical periods that have persistent biological effects
what is the mechanism of fetal programming
Mechanism: epigenetic modification of gene expression
give examples of fetal programming
3marks
Example: (3)
programmed’ adrenal axis overactivity in adulthood
Causal factor for metabolic syndrome
Increased vulnerability to coronary heart disease
describe the association between cortisol and fetal weight with 9am levels
Babies with a lower birth weight have a higher cortisol level
what is the LIFE COURSE MODEL
Factors operating at every stage of life affect health outcomes later in the future
‘PATHWAY OF RISK’ between events and health outcomes
what is the 3 possible worst outcomes of the life course model associated with
Worst outcome’ associated with: (3)
Low birth weight
Excessive weight gain in infancy / childhood
Adult obesity
How does the gut microbe influence diabetes t2 and metabolic syndrome
Differences in gut bacteria
Can be induced by diet e.g. high fat diet
Transplantation of faecal material alters insulin sensitivity
Mice and humans
what are the slow acting hormones and what do they signal
LEPTIN
INSULIN
decrease food intake
increase body expenditure
what are the Rapid-acting peptides that regulate meal sizes
Released from GI tract
Cholecystokinin (CCK)
-reduce eating
Ghrelin
-increase eating
PYY-via hypothalamus
-decrease eating for up to 12 hours
what type of neurons originate from the HYPOTHALAMUS(ARCUATE NUCLEUS)
‘Accelerator neurons’
AgRP neurons- release NPY
Nyp-increases eating by decreasing satiety
AGRP- blocks the melanocortin receptor
Brake neurons’
POMC neurons
-these are melanocortin peptides that decrease eating sensation
what is the LEPTIN (MICE))experiment
‘ob/ob mouse’
- Leptin deficient
‘db/db mouse’
-Mutation of leptin receptor
‘ob’ gene product = leptin
Mouse models of obesity
what does leptin treatment do in mice
It reduces obesity in the ob/ob mouse
what does Leptin do in humans
it behaves as the starvation signal and it causes permissive effect on puberty
what causes obesity in humans that is related to Leptin
Leptin deficiency due to mutation of receptor
how do you treat Obesity via lifestyle (diet)
4marks
DIET
-500-1000 kcal energy deficiency
-Low energy density
low sat fat, low sugar
fruit & veg (substitute for other foods)
- decrease portion sizes, decrease snacking
- Structured meals / meal replacements may help promote greater weight loss
how do you treat Obesity via lifestyle Pt 2
PHYSICAL ACTIVITY
Exercise 7 days / wk
30 mins moderate-high intensity OR
60 mins low intensity
10,000 steps
what is the concept of a VLCD
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
what is the target for lifestyle modification
- 10% weight loss ( ideal weight)
- 1-2 lb (0.5 – 1 kg) per week
- Some evidence that ‘ambitious’ goals promote more weight loss
what are the problems with lifestyle mods
4marks
- Most patients can achieve ~ 5-10 % weight loss / 1 year
- ‘Yo-yo’ dieting / regaining weight lost
- ‘Obesogenic environment’
- Weight loss results in hunger, satiety, metabolic rate
what are the best outcomes for lifestyle modifications
3marks
- Sustainable lifestyle changes
- Diet combined with exercise / physical activity
- Ongoing management is required to maintain weight loss
what does Orlistat do
MECHANISM
Binds & inhibits lipases in the lumen of the gut
Prevents the hydrolysis of dietary fat into absorbable free fatty acids / glycerol
Excrete ~ 1/3rd dietary fat
adverse effects of orlistat
Flatulence, oily faecal leakage, diarrhoea
decreased absorption fat soluble vitamins so :
ADEK
Supplement
what does Metformin do
oral hypoglycaemic agents
PHARMACOLOGICAL THERAPY-evaluate
PROBLEMS
- 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
THE FUTURE
All identified gut peptides / neuropeptides / their receptors are potential therapeutic targets / options!
-Gut hormones in combination most likely way forwards…
what are the surgical treatments available
Laparoscopic adjustable banding
Roux-en-Y gastric bypass
what is the Laparoscopic adjustable banding
Restrictive only
Inject / withdraw saline to adjust the diameter of the band
what is the Roux-en-Y gastric bypass
- Restrictive
- Malabsorptive
- Alterations in gut hormones and bile acid flow contribute to weight loss
Micronutrient deficiencies
-Supplement with iron, B12, folate, calcium, vitamin D
Dumping syndrome
-GI & vasomotor symptoms
why is the Roux-en-Y gastric bypass better long term than Laparoscopic adjustable banding
Endocrine factors important in effects
- Plasma from operated rats to sham-operated rats
- Ate 1/3rd less
Increased satiety seems to be key
- “I don’t like burgers any more……”
- F-MRI studies
Evaluate SURGICAL TREATMENT
ADVANTAGES
-Weight loss 25-30%
-Resolve or improve co-morbidities
Brings cost savings
DISADVANTAGES -Perioperative 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 --Though cost effective by 2 - 5 years, depending on co-morbidities and weight
what are the UK NICE guidelines for surgery
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
Recent onset T2DM:
Expedite bariatric surgery if BMI > 35
Consider surgery if BMI > 30
what is the UK Position bariatric surgery:NHS guidelines
- 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
What is the expected % weight loss from
- Lifestyle interventions
- Bariatric surgery
Weight loss 25-30%-surgery
10% weight loss