Obesity Flashcards
Obesity Canada new definition
Obesity is a chronic progressive and relapsing disease characterized by excess or abnormal adiposity that impairs health and social wellbeing
NOT defined as excess adiposity
Key definitions: multi-causal, long-term positive energy balance, leading to physiological/functional/structural abnormality and impairment and increases risk of chronic diseases and premature mortality
Body fat distribution
Brown fat deposits
Gynoid: pear shaped
Android: apple shaped (higher risk)
Brown fat heterogenous deposits in cervical, supraventricular and paraventricular regions
White fat: subcutaneous, intraobdominal, abdominal, gluteal, bone marrow, pericardial, intramuscular, retro-orbital, periarticular
Types of adipose expansion
Hypertrophy: cells grow in size, inflammation, hypoxic due to no vascularization, fibrotic
- Associated with early development of insulin resistance
Hyperplasia: De novo adipocyte differentiation, angiogenesis, delayed insulin resistance
BMI and waist
Lowest risk: low waist + healthy BMI
Increased risk: Overweight + normal waist or healthy BMI and large waist
High risk: overweight + high waist
Highest risk: obese class I (>30) + high waist
Prevalence of obesity associated with which factors
ethnicity (highest in African Americans), sex/gender (higher in women), education
Canada: lower in landed immigrants and those with higher ed
Health risks associated with obesity
Cardiometabolic risk: CVD, hypertension, diabetes
Cancer, apnea/asthma, hpatobilliary disorders (NAFLD + cholelithiasis), reproductive complications, surgical risk, psychosocial and emotional issues
*rapid weight loss increases risk of cholelithiasis esp in women
PCOS, gynecomastia
Intra-abdominal fat is an independent predictor of all-cause mortality
Increases all cause mortality
Etiological components of obesity
Energy balance/nutrition
Heredity
Education
Socioeconomic status
Culture
Psychology
Inactivity
Energy expenditure components in a sedentary obese person
Higher REE than a non-obese person due to large body size and extra muscle to carry weight (70-80%)
PAE 15-20%
Define hunger, satiety, satiation, and appetite
Hunger = physical sensation indicating need or intense desire for food
Satiety = feeling of fullness after eating
Satiation = state of being satisfactorily full between meals
Appetite = desire to eat (homeostatic and hedonic controls)
Central homeostatic control of food intake
Arcuate nucleus of the hypothalamus contains neurons groups which release NPY+AgRP and POMC neurons releasing CART/⍺MSH
NPY+AgRP –> Lateral hypothalamus produce orexins and MCH (orexigenic)
POMC neurons releasing CART/⍺MSH –> Paraventricular nucleus produces oxytocin and CRH (anorexigenic)
Peripheral homeostatic control of food intake peptides and hormones in stomach, gut, fat and pancreas
Stomach: ghrelin (orexigenic)
Gut: CCK, Oxyntomodulin, GLP-1, PYY (anorexigenic)
Fat: Leptin (anorexigenic)
Pancreas: Amylin, insulin, pancreatic peptide (PP) (anorexigenic)
Orexigenic hormones
Hypothalamus: NPY, AgRP, Orexins, MCH, Endocannabicoids and opioids
GI tract: ghrelin
How do genetics impact obesity risk?
Obesity is polygenic - multiple genes having small effects on predisposition
- twin studies 50-80% of BMI explained by genetic elements
- overfeeding identical twins produces similar weight gain
Rare congenital diseases
Susceptibility to developing obesity is genetic/epigenetic but not a cause of obesity
Genes involved in obesity
LEPR: leptin receptor
POMC: proopiomelanocortin
PC1: pro-hormone convertase-1
BDNF: brain-derived neurotropic factor
Major contributors (6% of cases):
FTO: fat mass and obesity associated gene
MCR4: Melanocortin-4 receptor
Other factors associated with obesity
Sleep
Pre-natal exposures (high maternal BMI)
Breast-feeding protection
Smoking cessation
Viruses (AD-36)
Toxins like endocrine disrupters
Microbiota (complex)
Obesogenic environmental
Impact of stigma/bias towards people with obesity
Contributes to increased morbidity/mortality independent of weight/BMI
Define: physical activity, exercise, physical fitness, active living
Physical activity: all leisure/non-leisure movement resulting in substantial increase energy expenditure
Exercise: form of leisure PA planned, structured and repetitive to improve/maintain physical fitness
Physical fitness: set of health/performance attributes that are skill related and ability to carry out daily tasks with vigor and alertness
Active living: when PA are integral to daily living
PAL scores
Bed/chair bound: 1.2
Seated/little movement: 1.3-1.5 (low)
Seated with movement or some strenuous activity: 1.5-1.7
(moderate)
Standing work/high activity: 1.8-1.9
(high)
Strenuous work/highly active or 30-60 min of strenuous activity 4-5x per week: 2-2.4
1 MET =
metabolic equivalent = energy cost of PA
1 MET = 3.5 ml O2 uptake/kg BW/min
Sleeping = .9 METs
Slow walk = 2.5 METs
Vacuuming = 3.5 METs
Swimming = 7 MET
Jogging = 10 MET
Stages of change model
