Week 11 Flashcards
What is obesity
Overweight and obesity are defined as abnormal or excessive fat accumulation that presents a risk to health
A crude population measure of obesity is the body mass index BMI, a persons weight in kg divided by the square of their height in m. A BMI equal to or> 25 iOS considered overweight
>30 obese
>40 severely obese
Obesity classification
18.5-24.9= healthy
25-29.9=overweight
30-34.9= obesity I
35-39.9= obesity II
40 or more= obesity III
Risk thresholds are:
Lower for adults of Asian family origin
Higher for older people
EOSS: Edmonton Obesity Staging System -staging tool
Stage 0- no sign of obesity related risk factors
Stage 1- obesity related sub clinical risk factors, dont need medical treatment
Stage 2- established obesity related comorbidities requiring medical intervention
Stage 3 - significant obesity related end organ damage
Stage 4-severe obesity related comorbidities
With this scale there’s a strong correlation between the stage you’re at and mortality
Metabolic syndrome
Medical term for a combination of diabetes, hypertension and obesity
Puts you at greater risk of getting coronary heart disease, stroke, myocardial infarction, all-cause mortality and cardiovascular mortality
Different organisations have different definitions they required the following combination of conditions:
Abdominal/central obesity, hypertriglycerideaemia, low HDL cholesterol, hypertension, fasting hyperglycaemia, microalbuminuria
The prevalence of obesity
Increasing in the uk
Higher in women than men however being overweight more common in men
Maternal weight gain and obesity in both parents can result in an increased likelihood of obesity in the offspring due to epigenetic mechanisms
Monogenic obesity
Multiple monogenic forms of obesity
Rare
Most implicated regulation of energy balance
Leptin, leptin receptor, POMC,MC4R
Leptin deficiency as a monogenic cause of obesity: undetectable leptin due to mutation in Leptin gene, treated successfully with injections of recombinant human leptin
Leptin/melanocortin pathway: MC4R agonist, setmelanotide
Obesity pathogenesis (why do people develop obesity)
Sustained positive energy balance:
-energy intake> energy expenditure
-treatment is based around principle of creating negative energy balance
Resting of body weight set point at an increased value:
-body weight set point- the body will defend its current weight at a higher level than normal when trying to lose weight
-occurs due to genes and biological factors
-biological factors: when we try to lose weight- the body reacts by changing hormone levels so hunger hormones increase and the satiety hormone levels go down, encourages energy intake , resting energy expenditure also decreases after weight loss body goes into energy saving mode
Biological causes of obesity
(Mono-) genetic or syndromic: Bardet Biedl
Hypothalamic : post radiation therapy, post surgery, hypothalamic tumour
Endocrine : Cushing’s, hypothyroidism, post pregnancy, menopause, GH deficiency
Addressing biological causes:
Medication; antidepressants, insulin
Mental disorders: eating disorders, depression
Lifestyle: lack of exercise, alcohol abuse, hyper caloric intake
Causes of obesity
Predisposed individuals (genetic, epigenetic, maternal programming)
In the “obesogenic” environment:
Westernised lifestyle
Reduction in home cooking/ takeaways
High availability of calorie dense/ processed food
Food marketing
Endocrine-disrupting chemicals EDCs
Socioeconomic factors
Low physical activity: built environment, IT based leisure time, transportation
Pathophysiological association of obesity and other diseases
Obesity:
Insulin resistance- diabetes mellitus
Inflammation & dyslipidemia - cardiovascular disease
Increased blood volume & high angiotensinogen- high BP
Increased visibility- stigma
Increased pharyngeal fat depots- sleep apnea (breathing stops and starts while sleeping)
Increased body mass- osteoarthritis
Cholesterol turnover- cholesterol gallstones
Increased estradiol (oestrogen steroid hormone)- breast/endometrial cancer
Obesity meets AMA criteria for a disease
A disorder of structure or function in a human, animal or plant, especially one that produces specific symptoms or that affects a specific location and is not simply a direct result of physical injury
Impairment of normal functions: physical impairment, altered physiologic function (inflammation, insulin resistance etc), altered regulation of satiety in hypothalamus
Characteristic signs or symptoms: increased body fat mass, joint pain, impaired mobility, low self esteem, sleep apnea, altered metabolism
Harm or morbidity: CVD, type 2 diabetes, metabolic syndrome, cancer, death
Weight loss & maintenance
Healthy eating campaigns
Weight loss programmes
Pharmacological treatment, VLED(very low energy diets)
Bariatric surgery
Metabolic adaptations to weight loss
Increase hunger hormones e.g. ghrelin, increase energy intake
Decrease satiety hormones e.g. amylin, insulin, leptin, GLP-1, PYY, CCK. Decrease energy expenditure
Increased hunger, decreased metabolic rate
Surgical interventions
Treatment option when all of the following fulfilled
BMI >40
BMI 35-40 and other significant disease that could be improved with weight loss
All appropriate non-surgical measures have been tried unsuccessfully
Person is/will be managed in level 3 service
Fit for anaesthesia and surgery
Person commits to long term follow up
First line option (instead of lifestyle/drugs) if BMI>50
Bariatric surgery
Adjustable gastric band AGB- inflatable band used to create a small pouch which limits food consumption. Don’t see much anymore, less effective 20% compared to 40-45% weight loss
Roux-en-Y gastric bypass RYGB- creates a smaller stomach and bypasses part of the intestines, results in increase in GLP-1 satiety hormone
Vertical sleeve gastrectomy- permanently removes most of stomach, leaving a sleeve shaped pouch, results in a decrease in Ghrelin hunger hormone
