Obesity lecture Flashcards
what is obesity?
1) Obesity is a chronic, life-threatening disease
2) An excessive accumulation of body fat sufficient to impair health
3) Independent risk factor - for at least 30 common health conditions
According to WHO, what are the BMI boundaries for the following and state the risk of co-morbidity for each:
1) normal
2) overweight
3) obese
4) severe obese
5) morbidly obese:
1) normal: 18.5-24.9
2) overweight: 25.29.9 - mild increase
3) obese : 30-34.9- moderate
4) severe obese: 35-39.9- severe
5) morbidly obese: over 40 - very severe
what is the formula used to calculate BMI?
BMI = Weight (kg)/Height (m)2
The measurement of waist circumference provides information about the distribution of body fat and is a measure of risk for conditions such as coronary heart disease (CHD). what size waist in men and women put them at increased risk of co-morbidity’s ?
1) men : increased risk over 94cm, Substantially
increased risk at over 102cm
2) women: increased risk at 88cm and substantially over 88cm
list some of the implications of obesity
1) heart disease
2) cancer
3) stroke
4) asthma
5) sleep apnoea
6) Type 2 diabetes
7) liver disease
8) reproductive problems
outline what causes obesity
1) Individual’s lifestyle choice
2) Abundant cheap palatable food, aggressively advertised and available 24/7, little need for physical activity at home or work
3) It is determined by genetic factors
Define: energy balance and outline the terms positive and negative energy balance
1) energy balance: State in which energy intake, in the form of food and /or drinks, matches the energy expended
2) Positive energy balance: Energy in > energy out
- Results in weight gain
3) Negative energy balance: Energy in < energy out
- Results in weight loss
list the components of daily energy expenditure and explain how they are different in a sedentary Person and an active person
1) Thermic effect of feeding: this is the same in a Sedentary Person as well as a active person
- energy expenditure above the resting metabolic rate, due to the cost of processing food for use in storage
2) Energy expenditure of physical activity: this is more in a physically active person
3) Resting energy expenditure- the amount of energy you use just existing: this makes up most of the sedentary Person daily energy expenditure.
- amount of energy, required for a 24-hours by the body during resting conditions.
list the factors that influence resting energy expenditure (REE)
1) Body composition
2) Gender
3) Age
4) Height, weight
5) Hormones e.g. thyroid hormone
6) Body temperature
7) Pregnancy
8) Fasting/malnutrition
what is yo-yo dieting?
1) Weight loss -> Loss of muscle mass -> reduced BMR -> Reduced requirements
- the problem is: when you loose weight you also loose muscle mass, muscle normally burns energy. so your reducing your BMR which reduces your requirements for energy
- best way to loose weight therefore is to gain more muscle so you loose more weight while resting
what is BMR?
Basal metabolic rate (BMR) is the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting).
what is The Barker Hypothesis ?
Adverse environments in foetal life and early childhood establish increased risk of disease in adult life
Describe how adverse environments in foetal life can lead to metabolic syndrome.
1) suboptimal maternal nutrition, placental abnormalities, other maternal factors (stress, infection, drugs)
2) all of the above lead to changes in fetal gene expression
3) leads to altered fetal growth metabolism
4) reduced birth weight: this now leads to conflicting postnatal environment- if the baby is born underweight the mother might over feed the child to rectify this and this leads to the child being overweight
5) metabolic syndrome
outline the The Barker Hypothesis
1) Under-nutrition in gestation induces programming of the pancreatic beta cells, muscle, liver, adipose tissues and neuroendocrine axis
2) Mismatch of poor prenatal environment and rich postnatal environment leads to maladaptation
3) increases risk of obesity, glucose intolerance and coronary heart disease in adult life
list the Evidence supporting the Genetic Influence of obesity.
1) Familial aggregation: Familial clustering of obesity in families
2) Twin studies: Greater concordance among monozygote compared with dizygote twins
- evidence where twins have been raised separately
how many genes may influence adiposity? and what factors do these genes influence?
1) >300 genes may influence adiposity
2) Genetic factors influence: body size and shape, body fat distribution, metabolic rate, brain chemistry
- Thrifty metabolism gene allows for inc fat storage to protect against famine
- Heritability of obesity estimated at ~ 40-60%
explain the cycle of feast and famine
1) Those that were better at fuel storage or utilization more likely to survive during famine
2) Over generations, we developed genetically to be exceptionally efficient at the intake and utilization of fuel
outline the likelihood of a child being obese in the following circumstances:
1) No obese parents
2) One obese parent
3) Two obese parents
1) no obese parents; Child =10% chance of obesity
2) one obese parent: Child = 40% chance of obesity
3) two obese parents: Child = 80% chance of obesity
explain why the rapid rise in obesity in last 30 years cannot be explained by genetics
1) There is no single gene except in rare circumstances
2) there are a lot of genes responsible and other factors going on.
3)
what were the outcomes of the Food4Me Study?
personalised nutrition increased dietary behaviour. so generic dietary advice should be avoided .there was no impact from understanding the phenotype and genotype as this did not lead to better outcomes for the individuals
what is Energy homeostasis? and what are the two types of feedback signals?
1) Energy homeostasis is a balance between energy input, as food intake, and energy expenditure.
2) short term and long term
outline the short term feedback signal of energy homoeostasis
1) Operates on a meal-to-meal basis
2) Determines the amount of food ingested in a single meal
3) Satiety factors include nervous signals initiated in the GI tract
outline the long term feedback signal of energy homoeostasis
1) Work over periods of weeks to years to regulate our energy intake & expenditure
2) Modulated by adipose tissue mass; major mediators are leptin and insulin
what is the control centre for apatite regulation?
1) The hypothalamus: receives and integrates neural, metabolic and humoral signals from the periphery