Regulation of Body Weight and Appetite

Questions and Answers

Which hormone is primarily associated with hunger signals released during fasting?

Leptin

Ghrelin (correct)

GLP1

CCK

What is a possible implication of impaired striatal dopamine release in obese individuals?

Increased eating behavior despite lower reward activation (correct)

Decreased reward anticipation when expecting food

Enhanced reward activation during meals

Increased appetite due to heightened dopamine sensitivity

What effect do non-esterified fatty acids (NEFA) have on insulin receptor sensitivity?

They have no effect on the insulin receptor.

They decrease insulin receptor sensitivity. (correct)

They increase insulin receptor sensitivity.

They activate the insulin receptor.

Which adipokine is known to decrease in Type 2 Diabetes Mellitus (T2DM)?

Adiponectin Signup and view all the answers

Which hormone is primarily derived from adipose tissue and plays a role in energy regulation?

Leptin Signup and view all the answers

What is a key function of brown fat in the human body?

Thermogenesis and energy balance Signup and view all the answers

What is the role of pro-inflammatory cytokines secreted by fat cells?

They decrease insulin receptor sensitivity. Signup and view all the answers

Which statement correctly describes the caloric usage of obese individuals?

They may use less calories during weight loss states compared to lean individuals. Signup and view all the answers

How does the hypothalamus interact with peripheral signals in the body?

It has a leaky blood-brain barrier that allows signal crossover. Signup and view all the answers

What type of fat decreases significantly with age and is primarily responsible for heat production?

Brown fat Signup and view all the answers

What is one of the anti-hyperglycemic adipokines mentioned?

Leptin Signup and view all the answers

Which of these hormones is classified as orexigenic and produced by the stomach?

Ghrelin Signup and view all the answers

Which cellular activity is increased by the activation of AMP-K?

NEFA oxidation Signup and view all the answers

What role does the vagus nerve play in the homeostatic system?

It synapses with the hypothalamus to relay peripheral signals. Signup and view all the answers

How do visceral adipocytes influence inflammation?

By recruiting macrophages and secreting pro-inflammatory cytokines Signup and view all the answers

Which adipose-derived factor is known to enhance insulin sensitivity?

Adiponectin Signup and view all the answers

What is the Body Mass Index (BMI) threshold for defining obesity?

BMI ≥ 30 kg/m2 Signup and view all the answers

How do pro-inflammatory cytokines contribute to insulin resistance?

Through serine phosphorylation of the insulin receptor Signup and view all the answers

Which of the following is a component of Activity-related Energy Expenditure (AEE)?

Non-exercise activity thermogenesis (NEAT) Signup and view all the answers

What is the role of DAMPs in cells during inflammation?

They enhance production of pro-inflammatory cytokines. Signup and view all the answers

Which inflammatory cytokines are primarily produced by the adipocyte in response to stress?

IL-6 and TNF-alpha Signup and view all the answers

What does a waist-to-hip ratio greater than 0.90 in men indicate?

Obesity risk Signup and view all the answers

What primarily causes oxidative stress in adipocytes during obesity?

Excessive lipid build-up Signup and view all the answers

Which of the following best describes Diet-induced thermogenesis (DIT)?

Energy expended in the process of digesting food Signup and view all the answers

What is the increased risk associated with obesity regarding infections?

Increased susceptibility to bacterial wound infections and SARS-COV2 complications Signup and view all the answers

What is the effect of a 5 kg/m2 increase in BMI on cancer mortality?

Cancer mortality increases by 10% Signup and view all the answers

Which system is NOT impacted by obesity-related complications?

Endocrine system Signup and view all the answers

What role does the immune system play concerning gut microbiota?

It facilitates a symbiotic relationship with commensal gut microbiota Signup and view all the answers

Which obesity-related condition does NOT show an increased risk?

Rheumatoid arthritis Signup and view all the answers

Chronic elevations of cortisol are correlated with which aspect of gut health?

Changes in gut microbiota function Signup and view all the answers

Which characteristic is associated with increased risk of dementia and stroke in obese individuals?

Atherosclerosis Signup and view all the answers

What factor is implicated in the microbiota-gut-brain axis relating to food intake regulation?

Chronic cortisol levels Signup and view all the answers

What is the primary difference between BMR and RMR?

BMR is measured under more stringent conditions than RMR. Signup and view all the answers

In individuals with a sedentary lifestyle, NEAT accounts for what percentage of energy expenditure?

6-10% Signup and view all the answers

What effect does underfeeding have on NEAT in inactive individuals?

NEAT decreases substantially. Signup and view all the answers

What factor is believed to explain 57% of the variability in spontaneous physical activity?

Genetic inheritance Signup and view all the answers

Which population type tends to increase spontaneous physical activity (NEAT) when overfed?

Compensators Signup and view all the answers

What happens to total energy expenditure (EE) in response to increased NEAT and EAT?

Total EE increases. Signup and view all the answers

How much can variations in NEAT differ between two similar-sized individuals?

Up to 2000 kcal/day Signup and view all the answers

In studies of weight loss, skeletal muscle efficiency is observed primarily as a result of:

Caloric restriction. Signup and view all the answers

What is a characteristic of the independent model of energy expenditure?

It states changes in energy expenditure are independent of budgeted energy. Signup and view all the answers

What is the effect of overfeeding on NEAT for the majority of individuals?

No change in NEAT, but increased total energy expenditure. Signup and view all the answers

Study Notes

Energy Expenditure and Weight Loss

Obese individuals may use more calories than lean individuals but show less calorie utilization during weight loss.
Reduced basal metabolic rate (BMR) is common in many obese individuals, but not all.

Regulation of Appetite

Satiety signals include leptin, GLP-1, CCK, PYY, and vagal afferents.
Hunger is primarily regulated by ghrelin, released from the stomach during fasting.
These signals target different nuclei in the hypothalamus to regulate food intake.

Insulin Resistance and Visceral Fat

Non-esterified fatty acids (NEFA) contribute to insulin resistance, with higher release from central fat than peripheral fat.
Increased NEFA concentrations can inactivate the insulin receptor through serine phosphorylation, disrupting glucose metabolism.
Adipokines, hormonal proteins from fat cells, can enhance or diminish insulin receptor sensitivity.
Pro-inflammatory cytokines from fat cells contribute to reduced insulin sensitivity and systemic inflammation.

Visceral Obesity and Inflammation

Visceral adipocytes attract macrophages, leading to the production of pro-inflammatory cytokines such as TNF-alpha and IL-6.
Elevated IL-6 levels cause increased CRP production from the liver, worsening insulin resistance.
Activation of DAMPs and elevated free fatty acids further promote inflammation and insulin resistance in visceral fat tissue.

Chronic Inflammation and Obesity

Excess lipid accumulation can induce oxidative stress in adipocytes, promoting inflammation through ROS production.
High concentrations of free fatty acids can activate pattern recognition receptors, leading to further inflammation and insulin resistance.

Obesity Definitions

Overweight is classified as BMI ≥ 25 kg/m²; obesity is BMI ≥ 30 kg/m².
Waist-to-hip ratio thresholds for obesity: >0.90 for men and >0.85 for women.

Energy Expenditure Components

Energy expenditure (EE) consists of resting metabolic rate (RMR), activity-related energy expenditure (AEE), and diet-induced thermogenesis (DIT).
RMR differs from basal metabolic rate (BMR) due to less stringent measurement conditions.
RMR and BMR are influenced significantly by fat-free mass (FFM).

Non-Exercise Activity Thermogenesis (NEAT)

NEAT accounts for spontaneous activity not classified as deliberate exercise, varying greatly between individuals.
Up to 2000 kcal/day variation can depend on factors such as occupation and lifestyle.
NEAT can increase with food overconsumption in some individuals but generally does not compensate fully for increased calorie intake.

Models of Energy Expenditure

Energy expenditure can change independently (independent model) or may lead to compensatory changes in another area (compensation model).
The literature identifies compensators, who increase spontaneous activity when overfed, and non-compensators, who show less increase in energy expenditure.

Exercise, Diet, and Insulin Resistance

Weight loss resulting from caloric restriction can enhance skeletal muscle efficiency.
Evidence suggests obese individuals may experience altered activation of the reward pathway compared to lean individuals, affecting eating behaviors.

Peripheral Signals in Appetite Regulation

Key hormones influencing appetite include leptin, adiponectin, ghrelin, GLP-1, and insulin.
These hormones interact at the level of the hypothalamus, which plays a vital role in hunger signaling.

Types of Adipose Tissue

White fat is the primary form of adipose tissue, serving as an energy store and endocrine organ.
Brown fat, mainly found in infants, is crucial for thermogenesis and energy balance.

Complications of Obesity

Respiratory issues primarily due to increased body mass and pressure on the thoracic cage.
Higher rates of gastroesophageal reflux and gallstones due to increased intra-abdominal pressure.
Correlation between BMI increases and cancer mortality rates.
Increased risk of infections and cardiovascular complications, including stroke and dementia.

Microbiota-Gut-Brain Axis (MGBA)

The MGBA comprises the autonomic nervous system, enteric nervous system, spinal nerves, and immune system.
Gut microbiota may influence food intake through various pathways, including the vagus nerve and intestinal mechanoreceptors.
Chronic stress can lead to microbiota composition changes, impacting metabolic and eating behaviors.

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Description

Explore the complex mechanisms of body weight regulation and appetite through this quiz. Delve into the roles of different satiety signals like leptin and GLP1, and understand how these factors influence energy expenditure in obese and lean individuals. Test your knowledge on the latest literature in this developing field.