Obesity I Flashcards
What is the basic definition of obesity?
Increased body weight due to excessive accumulation of fat
How is obesity defined in terms of body fat accumulation and health impact?
Obesity is defined as increased body weight due to excessive accumulation of fat, and also as a disease where excess body fat has accumulated to the point of adversely affecting health
What are some health risks associated with obesity?
increased risk of diabetes, hypertension, metabolic syndrome, osteoarthritis, and certain cancers
What is ectopic fat?
excess adipose tissue that is not classically associated with adipose storage, such as fat around the heart or kidney
What is the role of ectopic fat in the health risks associated with obesity?
Ectopic fat, which is fat stored in unusual places such as the heart and kidneys, significantly increases the risk of cardiometabolic disease.
What is the significance of adipocytes as endocrine cells in the context of obesity?
Adipocytes, or fat cells, function as endocrine cells that secrete various hormones and substances like adiponectin, leptin, and FFAs. These secretions play a role in metabolic and inflammatory processes linked to obesity.
How does obesity contribute to the development of Type 2 Diabetes?
Obesity, particularly abdominal obesity, leads to increased free fatty acids (FFAs), which are taken up by the liver and increase gluconeogenesis, which can result in hyperglycemia and eventually Type 2 Diabetes
What is HbA1c?
Average blood sugar over the last 2-3 months
What are some risk factors for Type 2 diabetes?
Low physical activity, aging, genetics, and obesity, especially abdominal obesity.
How does excess fat affect the liver?
It increases gluconeogenesis and can lead to dyslipoproteinemia (abnormal levels of lipoproteins in blood).
How does excess fat affect adipose tissue?
It reduces the antilipolytic effect of insulin, leading to a greater breakdown of fats and release of FFAs
How does excess fat affect skeletal muscle?
It causes insulin resistance, reduced glucose uptake, and reduced oxidative potential
How does excess fat affect the pancreas?
It causes hyperinsulinemia and potential beta-cell “failure”.
What is lipolysis?
The breakdown of lipids
What is the diagnostic criteria for hypertension?
Systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg. More recent guidelines use ≥130 mmHg and/or ≥80 mmHg.
How is obesity related to hypertension?
Obesity is increasingly recognized as a subtype of hypertension, that responds to weight loss and salt restriction
What percentage of overweight/obese individuals have hypertension?
40%
What percentage of normal-weight individuals have hypertension?
16%
What is primary (essential) hypertension?
High blood pressure with no obvious underlying cause, often associated with aging (90-95% of cases)
What is secondary hypertension?
Hypertension caused by other conditions, such as kidney problems, artery issues, or diseases
How does the sympathetic nervous system (SNS) relate to obesity and hypertension?
The SNS is elevated in both obesity and hypertension, which can be due to impaired baroreflex, increased leptin, FFAs, and angiotensin
What factors cause increased SNS activity in obesity and hypertension?
Impaired baroreflex, increased leptin, FFAs, and angiotensin.
angiotensin= hormone that regulates BP by increasing it
How do adipocytes contribute to vascular dysfunction?
Increased adipocytes result in inflammation which alters vascular function
What is adiponectin?
A hormone secreted exclusively by adipocytes
How does adiponectin relate to body fat?
Adiponectin is inversely proportional to the percentage of body fat.
What happens to adiponectin concentrations with weight loss?
Weight loss increases adiponectin concentrations.
What is the effect of adiponectin on insulin sensitivity?
Adiponectin increases insulin sensitivity
How does obesity increase the risk of cancer?
Individuals with obesity (BMI > 40 kg/m^2) have a higher risk of cancer compared to normal weight individuals
52% increased risk of cancer for men & 62% increased risk for women
How is obesity related to osteoarthritis?
Obesity is a major preventable risk factor for osteoarthritis, not just in weight-bearing joints but also potentially due to the inflammatory environment driven by cytokines
What role do cytokines play in osteoarthritis?
Cytokines like leptin, adiponectin, and resistin control local inflammatory processes
How does abdominal obesity affect health risks?
Individuals with the same BMI can have different health risks depending on abdominal fat. Excessive abdominal fat carries significant health risks
What is visceral fat?
Fat stored deep in the belly around the organs (intestines & liver) and is a key risk factor for disease.
What is the most effective way to reduce visceral fat?
by exercising
What is the relationship between obesity and various conditions?
Obesity is associated with many conditions, some expected (e.g., dyslipidemia) and some unexpected (e.g., some cancers). The relationship is not always causal
What is the relationship between sleep and obesity?
- Shorter sleep is associated with decreased levels of leptin and increased levels of ghrelin, which affect appetite and food intake
- Shorter sleep duration is associated with higher BMI
What is the role of cortisol in stress and obesity?
- Cortisol, the “stress hormone,” can be beneficial short-term but detrimental long-term
- can cause insulin resistance, abdominal obesity, hypertension, hyperglycemia, and dyslipidemia when chronically elevated.
How does sleep deprivation affect hunger?
Shorter sleep decreases leptin and increases ghrelin, both biological markers for hunger
What is Cushing’s syndrome?
A condition caused by excess cortisol of any cause
How does chronic stress affect weight?
- In response to chronic psychological stress, ~40% gain weight, ~20% remain weight stable and ~40% lose weight, with overweight/obese individuals tending to gain more weight
- Chronic stress can cause insulin resistance
How does acute stress affect food intake?
Individuals who are high reactors to stress and show a rise in cortisol eat more calories after a stressful test.
What is the role of genetics in obesity?
There is a biological predisposition to obesity, including a potential inherited or genetic predisposition but it can be modified by environmental factors
What is assortative mating and its implications for obesity?
- Assortative mating is when individuals with similar traits mate
- Lean individuals tend to mate with lean individuals
- Individuals with obesity tend to mate with individuals with obesity amplifiying the genetic pre-desposition to obesity
What is the heritability of obesity?
If a biological parent is obese, there is some sort of genetics at play but it can be modified by the environment
What is the role of NEAT (non-exercise activity thermogenesis) in weight management?
Differences between twins in weight gain can be attributed to NEAT because changes in BMR and TEF are similar.
What is the effect of exercise on visceral fat?
Exercise can lead to a significant drop in visceral fat.
How do genes interact with each other?
Gene-gene interactions occur when the expression of one gene affects the expression of another gene, which can impact obesity
What are Gene-Environment Interactions?
constant interactions between genes and environmental factors, that play a role in the development of obesity
What is an obesogenic environment?
An environment that promotes obesity where genetic predispositions can be more impactful.
What is epigenetics?
The study of cellular mechanisms that modify gene expression without changing the underlying DNA sequence
Can epigenetic changes be passed on?
Epigenetic changes may occur during a lifetime, or can be passed on to the next generation and may play a role in obesity
How is childhood obesity defined?
Most systems now use BMI, with age and sex-based percentile cut-off points
What are the CDC cutoffs for childhood overweight and obesity?
85th percentile of BMI = at risk for overweight; 95th percentile = overweight
What are critical periods for the development of childhood obesity?
prenatal and infancy stages, during which factors such as birth weight, breastfeeding, smoking, and exercise can impact obesity risks.
How is birthweight related to adult BMI?
The relationship between birth weight and adult BMI is often U-shaped or J-shaped. Both lower and higher birth weights increase the risk of adult obesity
How might breastfeeding affect BMI?
Breastfeeding may be associated with slightly lower BMI throughout life.
How is smoking during pregnancy related to child BMI?
Smoking during pregnancy may be associated with higher BMI in childhood.
How is exercise during pregnancy related to birthweight?
- Exercise during pregnancy is associated with lower rates of high birthweight
- exercise can modify the health coutcomes for babies
What is the Dutch Famine Study and what does it show about obesity?
individuals exposed to severe calorie restriction during the first and second trimesters of pregnancy had an increased risk of obesity at 19 years old.
What is the link between birth weight >4000g and risk of overweight/obesity?
Babies with a birth weight >4000g have an increased risk of being overweight/ having obesity
How does supervised exercise during pregnancy impact baby size?
Exercise during pregnancy is associated with a 31% decrease in the risk of a large baby
How does gestational weight gain relate to childhood obesity?
Early excessive weight gain during pregnancy is associated with gestational diabetes, postpartum weight retention, and childhood obesity
What are some key factors affecting energy balance?
Key factors affecting energy balance include sleep, stress, genetics, epigenetics, obesity in youth, and critical periods of development
How does a lack of sleep affect hunger?
Shorter sleep is positively correlated with increased hunger.
What is the connection between stress and abdominal obesity?
Chronic stress can lead to abdominal obesity.
What is type 1 diabetes?
- Diabetes that is primarily a result of pancreatic beta cell destruction and is prone to ketoacidosis.
- This form includes cases due to an autoimmune process and those for which the etiology of beta cell destruction is unknown
What is Type 2 diabetes?
Diabetes that ranges from predominantly insulin resistance with relative insulin deficiency to a predominant secretory defect with insuliun resistance
What is gestational diabetes?
refers to glucose intolerance with onset or first recognition during pregnancy
Diagnosis of diabetes
- Fasting plasma glucose >7.0 mmol/L. (Fasting = no caloric intake for at least 8 hours)
- Glycated Hemoglobin 0r HBALC greater than or equal to 6.5% in adults
