obesity Flashcards
what is obesity?
Obesity is a chronic, life-threatening disease
An excessive accumulation of body fat sufficient to impair health
Independent risk factor or aggravating agent for at least 30 common health conditions
classification of obesity
normal - BMI - 18.5-24.9
overweight -BMI - 25-29.9
obese - 30-34.9
severe obese- 25-39.9
morbidly obese - equal or over 40
what other conditions can obesity effect
- heart disease
cancer
stroke
liver disease
reproductive complications
depression/anxiety
sleep problems
asthma
type 2 diabetes
what causes obesity
inidivual life chouce
society - cheap food, adverts, availaibity, work from home
determined by genetics
how can you regulate weight
energy intake = energy outake
what does energy balance mean
negative
positive
“State in which energy intake, in the form of food and /or drinks, matches the energy expended”
Positive energy balance
Energy in > energy out
Results in weight gain
Negative energy balance
Energy in < energy out
Results in weight loss
what is yo-yo eating and BMR
Weight loss
Loss of muscle mass
Reduced BMR
Reduced requirements
what is the barkers hypothesis
“Adverse environments in foetal life and early childhood establish increased risk of disease in adult life”
Under-nutrition in gestation induces programming of the pancreatic beta cells, muscle, liver, adipose tissues and neuroendocrine axis
Mismatch of poor prenatal environment and rich postnatal environment leads to maladaptation
Increases risk of obesity, glucose intolerance and coronary heart disease in adult life
evidence for genetic influence
familial aggregation
twin studies
Familial aggregation
Familial clustering of obesity in families
Twin studies
Greater concordance among monozygote compared with dizygote twins
what does genetic factors influence
body size and shape
body fat distribution
metabolic rate
brain chemistry
what does thritfy metabolism gene allow
what is it
Thrifty metabolism gene allows for fat storage to protect against famine
Cycle of feast and famine
Those that were better at fuel storage or utilization more likely to survive during famine
Over generations, we developed genetically to be exceptionally efficient at the intake and utilization of fuel
probability of getting obesities
no parets obese
1 parent
both parent
no parent - 10 %
1 parent - 40%
2 parents - 80%
what is the energy homeostatis system
The energy homeostasis system:
is precisely regulated across the lifetime of an individual
promotes stability in the amount of body energy stored in the form of fat
2 types of feedback signals
There are two types of feedback signals:
Short-term
Meal-to-meal basis - determines amount of food ingested in a single meal
Satiety factors include nervous signals initiated in the GI tract
Long-term
Work over periods of weeks to years to regulate our energy intake & expenditure
Modulated by adipose tissue mass; major mediators are leptin and insulin
what is leptin
Secreted by adipocytes in proportion to the amount of stored fat
Primary way brain knows how much body fat is stored
Regulates long term body weight rather than short term appetite
Diurnal variation: peak at night
Acts in the CNS to suppress food intake
gut hormones -roles
cholecytoskin
secretin
GIP
motolin
ghrelin
gastrin
insulin and glucogen
pancreatuc polypeptide
amylin
GLP-1
GLP-2
cholecytoskin - gall bladder contraction, gastrointestinal motility, pancreatic exocrine, secretion
secretin - pancreatic exocrine, secretion
GIP - incretin activity
motolin - GI MOTILITY
ghrelin - hunger, growth horomone
gastrin - acid secretion
insulin and glucogen- glucose homeostatis
pancreatic polypeptide - gastric motility, satitation
amylin - glucose homesostatis, gastric motality
GLP-1 - incretin activity, satitation
GLP-2 - GI motality and strengyth
ocyntomodulin - satitation, acid secretion
PYY (3-36) - satitation
what is gherlin
Peptide hormone secreted by gastric mucosa
Levels rise just before meals and fall after
Increases food intake
Ghrelin administration in rats strongly stimulates feeding
High Ghrelin levels in Prader-Willi syndrome
Orexigenic (appetite stimulating) effects of ghrelin mediated through hypothalamus
Stimulates NPY neurons
plasma ghrelin rises with hunger
what is congnitive influences
Cognitive Influences = presence of others, favourite foods, time of day, free/abundant food, mood, stress.
Conclusion
Appetite is a process controlled by several neural, humoral and psychological factors
Systems are designed to maintain a stable body weight despite huge variations in day-to-day energy intake and expenditure
Regulation of energy balance primarily acts to protect us against starvation so with the changes to our environment over recent years, we are becoming increasingly obese as a nation
Genetically-based variations determine our susceptibility or resistance to an obesogenic environment and the ease with which people are able to lose weight
Our current understanding of weight regulation should encourage healthcare professionals to:
“make war on obesity, not the obese”
what is visceral adiposity
: fat as an endocrine organ
relative risk of health problems
greatly risk (over 5)
diabetes
gall bladder diswase
hypertension
dyslipidemia
sleep apnoea
breathlessness
nonalchoholic fatty liver disease
mod risk (2-3)
- CHD
-osteoarthiritis (knees)
hypdfuricaemia and gout
-gastro oesophageal reflux disease
increased (1-2)
- cancer
lower back pain
impaired fertility
increased anaesthetic risks
obstetric complications
what is obstructive sleep apnoea
Intermittent cessation of breathing during sleep due to the collapse of the pharyngeal airway, resulting in multiple apnoeic or hypopnoeic events
-normal
snoring
sleep apnoea
link between asthma and obesity
Robust epidemiological data links obesity with an increased risk of asthma – mechanism unknown
Related to increased inflammation
Adverse effect on lung function
cancer
Adipose tissue is an active endocrine organ
Mechanisms by which adipose tissue may influence cancer risk:
Production of sex steroid hormones (e.g., oestrogen, androgens)
Effects on insulin sensitivity and production of insulin-like growth factors
Actions on other hormones in adipose tissue (e.g., leptin, adiponectin)
Increases in oxidative stress and chronic low-grade inflammation that affect the body’s immune response
obesity and covid
Obesity linked with large significant increases in morbidity & mortality from COVID‐19 (Popkin et al, 2020).
Public Health England Report:
Excess weight can increase risk of serious illness & death from COVID-19.
treatment options
Behavioural Model - Behaviour change
Diet
Exercise
Medical Model - Medical management
Pharmacological management
Surgical management
shat are the pharmacological management of obesity
role
Orlistat/Alli
Manydifferent types of anti-obesity medicines have been tested in clinical trials, but the only one that has proved to be safe and effective is orlistat.
Reduce fat absorption
Eating fat causes anal leakage
Can cause substantial weight loss
what are the possible surgical management
vertical sleeve gastrectomy
ajustable gastric band
gastric bypass
conclusion
Obesity is a chronic life-threatening disease with significant medical, psychological, social and economic consequences
It substantially increases mortality and morbidity mainly by increasing the risk of developing diabetes, hypertension and cardiovascular disease
It also plays a role in cancer, reproductive health and mental health
The majority of the adverse effects associated with obesity can be reversed or attenuated by weight loss which should be an integral part of the treatment of these morbidities
