Obesity Flashcards
What is the definition of obesity?
Increased body weight due to excessive accumulation of fat.
Also defined as a disease in which excess body fat has accumulated such that health may be adversely affected (Kopelman, 2000)
What are common risks associated with obesity?
- Diabetes
- Hypertension
- Metabolic syndrome
- Osteoarthritis
- Cancer
These conditions highlight the serious health implications of obesity.
What biological mechanisms are involved in obesity?
- Free Fatty Acids (FFA)
- Ectopic fat
- Insulin resistance
- Adipocytes as endocrine cells
- Inflammation
Understanding these mechanisms is crucial for addressing obesity.
True or False: Obesity, chronic diseases, and physical activity/nutrition are interrelated.
True
They influence each other, suggesting a complex relationship rather than a one-way causation.
What does HbA1c measure?
Average blood sugar over the last 2-3 months.
It is used to assess the risk of type 2 diabetes.
What fasting plasma glucose (FPG) level indicates type II diabetes?
7 or higher
FPG is one of the diagnostic criteria for type II diabetes.
What is A1C?
Measuring average blood glucose values over 2-3 months
(higher than 6.5 is type II).
What is random testing for type II diabetes?
Taken anytime, higher than 11.1 indicates type II.
What is the difference between type I and type II diabetes?
Beta cell destruction causes type I.
Type II ranges from insulin resistance with insulin deficiency, to a secretory defect with insulin resistance.
What are the levels for FPG, HBA1C, 2hPG, and random PG that indicate type II diabetes?
FPG: ≥ 7.0 mmol/L
HBA1C: ≥ 6.5%
2hPG: ≥ 11.1 mmol/L
Random PG: ≥ 11.1 mmol/L
List the risk factors for type 2 diabetes.
- Low physical activity
- Aging
- Genetics
- Obesity (especially abdominal obesity)
These factors contribute to the likelihood of developing type 2 diabetes.
What are the different types of testing for type II diabetes?
FPG: Fasting for 8 hrs minimum.
HBA1C: Avg blood sugar over 2-3 months.
2hPG: Drink sugary drink, 2 hours later take blood glucose levels.
Random PG: Taken anytime.
What is the impact of physical activity during pregnancy regarding gestational diabetes?
40% reduction in chances of developing gestational diabetes.
Physical activity is beneficial for reducing risks associated with pregnancy.
While gestational diabetes increase chances of getting ‘regular’ diabetes postpartum.
What percentage of the population has T2DM
5-10%
10-20% of overweight/ obese populations has T2DM.
Fill in the blank: Increased adipose tissue leads to increased _______.
Free Fatty Acids (FFAs)
What is a proposed explanation for the link between obesity and T2D?
Increases in adipose tissue causes an increase in FFAs.
More FFAs have a detrimental impact on insulin intake by the liver.
As a result, gluconeogenesis increases (glocose production from FFAs).
(Adipose tissue becomes FFAs)
Increased glucose production results in increased insulin production.
The compensatory increase in insulin results in eventual B-cell failure > hyperglycemia = T2D.
What is lipolysis?
Breakdown of lipids
What are the blood pressure criteria for hypertension according to Canada EU?
Systolic BP (SBP) ≥140 mmHg
and/or
Diastolic BP (DBP) ≥90 mmHg
What are the blood pressure criteria for hypertension according to AHA?
Systolic BP (SBP) ≥130 mmHg
and/or
Diastolic BP (DBP) ≥80 mmHg
What percentage of overweight/obese individuals have hypertension?
40%
Obesity is often recognized as a subtype of hypertension.
16% of ‘normal weight’ individuals have hypertension.
What is the role of the sympathetic nervous system in obesity and hypertension?
Elevated sympathetic nervous system responses are linked to both conditions.
High level of SNS responses, more likely to have or develop HTN.
Increased signals to constrict blood vessels lead to higher blood pressure.
What are the types of hypertension?
Primary (/essential): High BP with no obvious cause. Aging!
90-95%
Secondary: Caused by other conditions affecting kidneys, arteries, or diseases (renal failure, pregnancy…)
What is ectopic fat?
Excess adipose tissue that is not classically associated with adipose tissue storage (e.g., heart, kidney).
Ectopic fat significantly increases the risk of cardiometabolic diseases.
Obesity increases risk for…
Cancer and osteoarthritis
What is the number one preventable risk factor for osteoarthritis?
Obesity.
What other factors increase risk of osteoarthritis?
Inflammatory environment, sendentary lifestyle.
Inflammatory environment: Cytokines (leptin, adiponectin, resistin control local inflammatory processes)
Strongly associated with glucose and lipid disregulation.
What causes increased SNS responses?
Impaired baroreflex, increased leptin, FFAs, angiotension…
Increased adipocytes also result in inflammation which alters vascular function.
What is visceral fat and why is it a health risk?
Hidden fat stored deep in the belly around organs (intestines/liver/heart/kidneys…), associated with increased health risks.
Causes apple shape or beer belly.
It is a key risk factor for insulin resistance and impaired glucose tolerance.
What is abdominal obesity?
A condition where excessive visceral fat has built up around the stomach.
Is BMI a good indicator of health? Why or why not?
No. Individuals with the same BMI (low or high) can have vastly different health risks. High amounts of muscle can also increase BMI…
Abdominal fat is the better indicator.
What is ectopic fat? How can it be managed?
Excess adipose tissue that is not classically associated with adipose tissue storage (e.g., heart, kidney).
Can be managed through exercise.
What is the riskiest type of fat? Why?
Ectopic fat.
Result of a positive energy balance over a long period of time; it significantly increases the risk of cardiometabolic disease.
Embeds through muscles, in the liver and heart…
What is/causes a positive energy balance?
A high energy intake and/or low energy expenditure (PA, sedentary time, vigourous exercise).
Describe the relationship between obesity and the associated conditions.
Not always causal.
Causal mechanisms are only partially understood.
What is the relationship between sleep and obesity?
Less sleep (<7 hrs) is associated with higher BMI.
Sleep deprivation can increase food intake and alter hormonal levels affecting appetite.
Is excess sleep also associated with a higher BMI?
Yes but not often. Some show a U shaped curve, with 9+ hours showing a higher BMI.
How is obesity interrelated with sleep apnea/ feeling tired, and getting less sleep?
Sleep apnea causes a very restless sleep, resulting in being more tired and getting much less sleep overall. Low levels of sleep are associated with obesity.
What experimental evidence proves the link between lower levels of sleep and obesity/weight gain?
Sleep deprivation test in rats and humans.
Two nights of sleep restriction (4 hrs max) proved to increase desire for starchy, salty and sweet foods.
What is the effect of cortisol on obesity?
Cortisol causes insulin resistance and is linked to abdominal obesity.
Most potent glucocorticoid.
Long-term elevation of cortisol can lead to weight gain.
What are the two hormones associated with sleep?
Leptin and ghrelin.
Less/shorter sleep showed a decrease in leptin and an increase in ghrelin.
Positive correlation found between hunger and physiological markers of appetite (ghrelin/leptin ratio).
What is Cushing’s syndrome?
Result of excess cortisol of any cause, but main cause is medication (certain glucocorticoids)
Producing higher levels of cortisol, chronically over time and associated with abdominal obesity.
(“Large belly but skinnier legs”)
Exercise or sleep to reduce cortisol (exercise will acutely raise stress/cortisol levels but over time creates a reduction)
What is the significance of epigenetics in obesity?
It may contribute to the risk of obesity through inherited or genetic predisposition.
Assortative mating patterns also influence obesity prevalence in offspring.
What evidence shows the association between chronic stress and obesity?
Dallman 2010.
In response to stress chronic psychological stress:
~40% gain weight
~20% are weight stable
~40% lose weight
Those who are overweight/obese tend to gain weight more often.
Describe the results of the Quebec 100-day Overfeeding Experiment.
Body weight increased by 8 kg after overfeeding 1000 kcal over baseline daily for 100 days.
(Surplus of 84 000kcal over 100 days)
% Fat from 11% to 18%.
FFM from 53 to 56kg.
RMR increased by 10%
Fasting insulin increased by 50%
Abdominal fat cell size increased by 100%
Muscle oxidative potential decreased by 15%
The study involved genetically identical twins and highlights the impact of calorie surplus on weight gain.
What is the total caloric intake during the overfeeding treatment in the Quebec 100-day study?
84,000 kcal
This was achieved by overfeeding by 1000 kcal over baseline, 6 days a week, for 100 days.
What percentage of the daily intake was composed of carbohydrates in the Quebec 100-day overfeeding study?
50%
The composition of daily intake included 15% protein, 35% fat, and 50% carbohydrates.
What was the increase in body weight observed in the Quebec 100-day study?
8 kg
This was a significant change noted in the results of the overfeeding treatment.
How much did the percent fat increase in the Quebec 100-day study?
From 11% to 18%
This reflects a substantial increase in body fat percentage due to the overfeeding.
What was the change in fasting insulin levels during the Quebec 100-day overfeeding treatment?
Increased by 50%
This indicates a significant metabolic response to the overfeeding.
True or False: The basal metabolic rate (BMR) and thermal effect of feeding (TEF) were different between genetically identical twins in the Quebec 100-day study.
False
BMR and TEF were the same, suggesting the difference in weight gain was due to behavior.
What does NEAT stand for and how does it relate to weight gain?
Non-Exercise Activity Thermogenesis
NEAT refers to the energy expended for everything we do that is not sleeping, eating, or sports-like exercise.
What was the estimated energy deficit created by the twins in the Quebec Negative Energy Balance Study?
58,000 kcal
This was achieved through exercise over a period of 93 days.
What was the difference between both Quebec Twins studies?
While the Quebec 100-day study focused on overfeeding, the Negative Energy Balance study created an energy deficit through exercise.
What was the result from the Negative Energy Balance study?
Negative energy balance showed a tight relationship between amount of weight lost by twin A and twin B.
Tighter relationship shown in the graph than that from the previous study (100-day overfeeding study).
Much less fidgeting (less of a contribution from NEAT) when already working out.
What is an obesogentic environment?
Increased amount of available food, limited ability for PA.
Has a different effect on everyone, depending on genetic predisposition.
What is the definition of epigenetics?
The study of cellular mechanisms that modify gene expression without changing the underlying DNA sequence
Epigenetic changes can occur during a lifetime or be passed on to the next generation.
Do gene-environment interactions occur for obesity phenotypes?
Yes, limited studies have addressed this issue though.
Obesogentic environments.
What are gene-environment interactions?
Interactions taking place between genes (and sequence variations in such genes) and all kinds of factors in the environment which necessitate a cellular response.
What percentile of BMI is considered at risk for overweight in children?
85th percentile
95th percentile would be overweight.
This classification is based on CDC growth charts.
What would BMI in adulthood be for youth in the 85th and 95th percentiles?
25 and 30
What is the relationship between birth weight and adult BMI according to the critical periods discussed?
J-shaped or U-shaped relationship
This indicates that both low and high birth weights can be associated with higher BMI in adulthood.
What are the preantal and infancy critical periods?
Birthweight
Breastfeeding
Smoking (higher BMI in childhood)
Exercise (lower rates of high birthweight but longer term studies are still needed)
Pregnancy complications (GDM vs. preeclampsia)
Birth weight/early life nutrition
Fill in the blank: The Dutch Famine Study showed that exposure to famine in the ____ trimester resulted in lower rates of obesity.
third
This suggests that the timing of nutritional exposure during pregnancy significantly affects later obesity risk.
Fill in the blank: Exposure to famine in the first and second trimesters results in ___.
An increased risk of obesity at 19 years.
Why does famine exposure affect obesity rates differently (depending on the trimester)?
3rd trimester is when babies gain fat. Being unable to gain in the 3rd trimester results in lower levels overall throughout life.
Mechanisms by which babies change weight are adjusted in 1st/2nd trimester babies, as well as numerous other factors; development, metabolism, appetite.
What is the risk associated with birth weight over 4000g?
66% increased risk of being overweight or developing obesity.
PA during pregnancy can change this.
This risk is supported by data from multiple cohort and case-control studies.
How does timing of exposure to weight gain during pregnancy affect the baby’s weight?
Early excessive weight gain may alter in utero environment to promote obesity.
Gaining above recommended amounts in early pregnancy or throughout, baby will gain excessive fat.
Early GWG has been linked to gestational diabetes, postpartum weight retention and childhood obesity
What impact does physical activity during pregnancy have on the baby?
It can modify health outcomes of the baby.
Exercise during pregnancy has been shown to decrease the risk of having a large baby.
