A. OBESITY Flashcards
what is obesity
- too much body fat in the ‘wrong place” (abdomen)
‘apple’ = fat in abdomen, do an inflammation test for cytokines, greater risk of complications
‘pear’ = fat in hips, thigh and buttocks, not as great a CV risk
what causes obesity
- chronic +ve energy balance
- too much energy intake or
- too little energy expenditure
how do we assess obesity
- body mass index
= weight (kg)/height² (m²)
(18.5-24.9 is healthy) - skin folds thickness
- assumes a constant relationship between SC and total body fat
- bicep and triceps common - body shape
- waist circumference: measure of intra abdominal fat
- apples or pears: waist:hip ratio
- risk of high total cholesterol, low HDL cholesterol, high BP
obesity statistics 2021
- 69% men
- 59% women
what is the biggest threat to women’s health
obesity
consequences of obesity
- CHD (angina, heart attack)
- increases BP
- increases plasma cholesterol levels
- increases risk of T2DM
(additional risk factors for CHD)
what cancer can body fat decrease risk of (probable)
- breast (pre-menopausal)
what cancers can body fatness increase risk of (convincing)
- Oesophagus
- Pancreas
- Liver
- Colorectal
- Breast (postmen)
- Endometrium
- Kidney
what cancers can abdominal fat increase risk of (convincing)
- colorectal
what cancers can body fatness increase risk of (probable)
- Mouth
- Stomach
- Gall bladder
- Ovary
- Prostate
what cancers can adult weight gain (ie around abdomen) increase risk of (probable)
- breast (postmen)
what study shows a link to breast cancer
skirt size increase
causes of obesity
- genetics (leptin deficient?)
- diet - high fat and high energy density
- low physical activity
- pregnancy (difficult to lose weight after)
- ageing (metabolic rate decreases as older, decrease intake)
what is the first thing that should be done before starting obesity treatment
- achievable target set
- 5-10% of original weight
- max weekly loss of 0.5-1kg
- may still have BMI > 25kg/m²
what is the principle of weight loss
- energy balance must be negative
3 ways of obesity treatment
- individualised modest energy restrictive diet
- very low calorie diets
- current POMs
individualised modest energy restrictive diet
- 500 kcal/day less than calculated amount
- slower weight loss, based on healthy eating guidelines - better long term success but need motivation to change
- should still provide correct balance of nutrients. Based on patient’s age, sex, weight
very low calorie diets
- commercially-prepared diet
- medical supervision only
- for very obese patients who need to lose weight quickly
– typically 400- 600 kcal/day for several days/weeks but max of 12 weeks - milkshake type preparation + protein, vitamins, minerals
- rapid weight loss if comply
Orlistat
- tetrahydrolipstatin
- synthesised derivative of lipostatin
- inhibits gastric and pancreatic lipase so we can’t digest fats taken in and fatty acids not absorbed
- minimal absorption
- take before each main meal
- 30% inhibition of lipases at normal therapeutic doses (lose 200kcal per day)
- need to combine with a low fat diet
side effects of Orilstat
- steatorrhoea = fatty, foul-smelling faeces which may help to reduce fat intake
(faecal incontinence - adult nappies) - reduced absorption of fat so need to monitor fat soluble vitamin status (supplements?)
prescribing guidelines for Orilstat
- combine with reduced calorie diet
- BMI > 30 kg/m² or BMI > 28 kg/m² if other risk factors eg T2DM, hypercholesterolaemia, hypertension
- should only be continued after 12 weeks if weight loss exceeds 5%
- treatment > 12 months should only be done after discussion potential benefits and risks with patient
dosing of Orilstat
- 120mg immediately before, during, or 1 hour after reach main meal
- 360mg max each day
- if meal contains no fat = miss dose
what is OTC Orilstat
- Alli
- 60mg tds
- combined with reduced fat diet
- BMI>28
- review after 12 weeks
- try diet and exercise approach first
what controls our appetite
hypothalamus
Liraglutide and Semaglutide
- Saxenda and Wegovy
- GLP-1 receptor agonists
- SC injection
- suppress appetite as increased secretion of POMC/ CART - anorexigenic neurons
- GLP-1 can reduce high fat food intake by suppressing dopamine signalling which has an effect on reward pathways
- very expensive
prescribing guidelines for Liraglutide and Semaglutide
- BMI > 30 kg/m² or BMI > 28 kg/m² if other risk factors
- care with T2DM: is patient already on GLP-1 agonist?
- monitor after 12 weeks and stop if less than 5% weight loss
how is wegovy also used nowadays
weight loss drug
Mysimba (naltrexone & bupropion)
- dopamine is released from NTs in brain then taken back into neurones normally - signal switched off
- when dopamine levels increase, stimulation of opioid receptors which switches off signal
- bupropion is an inhibitor of dopamine reuptake hence there is an increased level of dopamine to interact with receptors so interferes with reward pathway
- naltrexone is an opioid receptor antagonist hence switches off feedback mechanism and there is an increase in dopamine in brain
- similar efficacy as Orlistat
- not recommended by NICE due to cost-effectiveness
- licensed but not through NHS, only private
Phentermine (US)
- not licensed in UK
- increases catecholamine levels in brain which increases CV risk
- peripheral effects: increase HR, BP, palpitations
- Qsymia approved by FDA 2012 in US and refused by EMEA October 2012 due to CV risk
what obesity drugs have been suspended
- Sibutramine due to increasing BP and CV risk
- Rimonabant due to blocking cannabinoid CB1 receptors which increases risk of depression
what obesity drugs are no longer recommended
Dexfenfluramine, fenfluramine and phentermine no longer recommended due to increasing BP
which hormones stimulate food intake
Ghrelin
which hormones inhibit food intake
Leptin
Insulin
PYY
GLP-1 (for T2DM)
*see last years lectures
surgical approaches to treatment of obesity
- gastric bypass
- bariatric surgery
