Nutrition and Appetite Regulation

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Questions and Answers

What role does Cholecystokinin (CCK) play in regulating food intake?

Increases food intake during fasting

Suppresses food intake (correct)

Promotes fat storage

Stimulates appetite

Which peptide is responsible for stimulating food intake?

Peptide tyrosine tyrosine (PYY)

Ghrelin (correct)

Glucagon-like peptide-1 (GLP-1)

Cholecystokinin (CCK)

In which scenario were leptin injections found to be ineffective?

In individuals with a healthy weight

In adolescents with obesity

In individuals undergoing weight loss diets

In obese adult humans (correct)

How does Glucagon-like peptide-1 (GLP-1) affect appetite?

Decreases hunger sensation Signup and view all the answers

What is a common effect of weight loss on ghrelin levels in dieters?

Ghrelin levels increase post-diet Signup and view all the answers

What is the primary function of the hypothalamus in relation to hunger?

It triggers chemical messengers that create the sensation of hunger. Signup and view all the answers

What is satiation best defined as?

The satisfaction felt during a meal that prompts one to stop eating. Signup and view all the answers

Which term describes the energy expenditure required for essential physiological functions at rest?

Basal Metabolic Rate (BMR) Signup and view all the answers

What does satiety affect in relation to eating habits?

The frequency of meals consumed throughout the day. Signup and view all the answers

How long must one refrain from food or exercise to accurately measure Basal Metabolic Rate (BMR)?

12 hours Signup and view all the answers

What is the Thermic Effect of Food (TEF) associated with?

The energy expenditure related to digestion and absorption of nutrients. Signup and view all the answers

Which of the following is NOT included in the determination of daily caloric needs?

Energy Burned at Rest Signup and view all the answers

What is the typical maximum duration after a meal that the thermic effect of food (TEF) peaks?

1 hour Signup and view all the answers

What is the average percentage for the thermic effect of food (TEF)?

10% Signup and view all the answers

Which of the following macronutrients has the highest thermic effect of food (TEF)?

Protein Signup and view all the answers

How is the Exercise Metabolic Rate (EMR) best defined?

Calories required for physical activity Signup and view all the answers

How much total energy expenditure would a 75 kg man consume walking at 3.5 mph for 30 minutes if he burns 0.104 kcal/min/kg?

156.6 kcal Signup and view all the answers

Using the equation developed by the DRI Committee, what's the EER for a 22-year-old female, 5 ft 6 in tall, weighing 132 lb with a low activity level?

1800 kcal Signup and view all the answers

What is the energy expenditure for an 80 kg person raking leaves for 4.5 hours at a rate of 0.091 kcal/min/kg?

454.5 kcal Signup and view all the answers

What is the main purpose of calculating the Total Energy Requirement?

To determine energy balance for weight maintenance Signup and view all the answers

What is the physical activity factor (PA) used for in determining Estimated Energy Requirements (EER)?

To quantify daily energy expenditure from activity Signup and view all the answers

What is the formula used to calculate the Basal Metabolic Rate (BMR) for males?

24 x body weight (kg) Signup and view all the answers

How does BMR change with age after growth has stopped?

BMR decreases by about 2-5% per decade Signup and view all the answers

What contributes to an increase in BMR?

Strenuous exercise Signup and view all the answers

Which of the following factors would NOT increase BMR?

Body composition with higher fat mass Signup and view all the answers

What percentage above BMR is the Resting Metabolic Rate (RMR) approximately?

30% Signup and view all the answers

What is the Thermic Effect of Food (TEF)?

Energy required to digest and metabolize food Signup and view all the answers

Which hormone is linked to an increase in BMR?

Leptin Signup and view all the answers

Which of the following factors does NOT directly affect BMR?

Mattress quality Signup and view all the answers

After what physical activity does BMR remain elevated for about 30 minutes?

Strenuous exercise Signup and view all the answers

What primarily characterizes hyperplastic obesity?

Increase in the number of fat cells Signup and view all the answers

What role does lipoprotein lipase (LPL) play in fat metabolism?

Promotes fat storage in fat and muscle cells Signup and view all the answers

How does LPL activity differ between obese and lean individuals?

Obese individuals have higher LPL activity in their fat cells Signup and view all the answers

What is a significant contributing factor to the increasing obesity rates, according to the content?

Increased energy consumption Signup and view all the answers

What impact does thyroid function have on fat cell metabolism?

It regulates protein, fat, and carbohydrate catabolism Signup and view all the answers

What is the relationship between weight loss and LPL levels?

LPL levels increase after weight loss, especially in obese individuals Signup and view all the answers

Which body fat distribution pattern is observed due to LPL activity in women?

Lower body fat distribution in hips and thighs Signup and view all the answers

What theory explains the body's tendency to maintain a certain weight?

Set Point Theory Signup and view all the answers

How do sex hormones influence LPL activity?

They vary LPL activity based on gender Signup and view all the answers

What is a potential consequence of having a naturally low BMR due to hypothyroidism?

Increased fat accumulation due to lower metabolic rate Signup and view all the answers

Study Notes

Energy Balance

1 kg = 2.2 lbs
1 gram of fat = 9 kcal
1 lb = 454 grams
454g x 9 kcal = 4086 kcal
Fat cells (adipocytes) contain more than just fat; 87% fat.
1 lb body fat = 3500 kcal
Other constituents: water, protein (hormones)

Weight Loss

To lose one pound/week:
- Eat 500 kcal less every day
- Exercise to use up 500 kcal every day
Or
- Combination of diet (less 250 kcal) and exercise (burn 250 kcal): 500 kcal x 7 days = 3500 kcal/week
Safe weight loss: 1-2 lbs/week (0.5-1.0 kg/week)
10% of body weight in 6 months
Amount of weight loss depends on body weight

Energy Balance Definition

Weight is a balance between energy consumed and energy expended.
Energy In = Energy Out, maintains body weight.

Measuring Energy in Foods: Bomb Calorimeter

Instrument used to determine energy (kcal) content of food.
Measures heat energy released when a dried food is combusted.
Energy released in form of heat when bonds break (H2O and CO2 released).
Amount of heat given off = direct measure of food's energy value.
kcal = units of heat energy.

Food Intake Definitions

Appetite: Sensations of hunger, satiation, and satiety that prompt eating or not eating.
Hunger: Physiological response to a need for food, primarily from chemical messengers in the hypothalamus.
Satiation: Feeling of satisfaction and fullness during a meal, determining how much food is consumed.
Satiety: Feeling of satisfaction and fullness after eating, determining how much time passes between meals.

Energy Out: Determination of Daily Caloric Needs

Daily caloric needs are determined by basal metabolism, thermic effect of food, and activity.
Sedentary person (1800 kcal/day)
Physically active person (2200 kcal/day)

Basal Metabolic Rate (BMR)

Energy required for essential physiological functions under resting conditions.
Measured after 12 hours without food or exercise.
Males: 24 x body weight (kg)
Females: 23 x body weight (kg)
BMR decreases by 2-5% per decade after growth stops.
Exercise increases BMR, elevated for about 30 minutes after, or several hours depending intensity

Resting Metabolic Rate (RMR)

Energy required for normal daily sedentary activities (walking, sitting, standing).
Approximately 30% above BMR.

Factors Affecting BMR/RMR

Increasing body temp (fever)
Environmental temperature (heat, cold)
Stress (epinephrine)
Body composition (FFM - muscle, fat mass - body fat)
Body surface area (increase in height, increasing body weight)
Physical activity
Herbal supplements (ephedrine)
Thyroxin production (T4) released from thyroid gland
Hormones (leptin)
Nicotine, caffeine
Growth (children, pregnancy)
Aging
Fasting, low kcal diets, starvation

Thermic Effect of Food (TEF) or Diet Induced Thermogenesis

Energy needed to digest, absorb, transport, metabolize, and store nutrients.
This increases energy expenditure, causing body temperature to rise slightly for several hours after eating.
TEF reaches maximum within one hour after a meal.
TEF varies depending on food quantity and type.
Average TEF = 10%

Exercise Metabolic Rate (EMR)

kcal required for physical activity.
Many methods to calculate energy expenditure during exercise.

Intensity of Different Activities

Activities of daily living, moderate, vigorous activities. (Examples provided for each group )

Calculating kcal Expended during Exercise

(Table of activities, kcal/lb/min, and calories per minute at different body weights.)

Estimating Energy Requirements (EER) Formulas

Males (19 and older): EER = 662 - 9.53 x age + PA x [(15.91 x wt) + (539.6 x ht)]
Females (19 and older): EER = 354 - 6.91 x age + PA x [(9.36 x wt) + (726 x ht)]

EER Physical Activity Factors

(Values provided in a table according to age and sex). Sedentary, low active, active, very active.

Calculating the EER for a specific individual (example provided)

Defining a Healthy Body Weight:

Height/Weight Tables
BMI
% body fat
Body shape
Body fat distribution
Waist hip ratio
Waist circumference

Body Mass Index (BMI): WHO Classification

Underweight (<18.5 kg/m²)
Normal Range (18.5-24.9 kg/m²)
Overweight/pre-obese (25.0-29.9 kg/m²)
Class I Obesity (30.0-34.9 kg/m²)
Class II Obesity (35.0-39.9 kg/m²)
Class III Obesity (≥40 kg/m²)

BMI and Mortality

Graph showing correlation between BMI and mortality risk

Calculating BMI (example provided)

Determining BMI (example provided)

Determining Body Fat Methods

Fat fold measures
Hydro densitometry
Bioelectrical impedance
Air Displacement plethysmography
Dual energy X-ray absorptiometry (DEXA)
MRI

Body Shape: Body Fat Distribution

Subcutaneous fat, intra-abdominal fat (visceral fat), intramuscular fat, Intramyocellular lipids (IMCL)
Extramyocellular lipids (EMCL)

Body Shape: Apple and Pear

Apple obesity (Android): abdominal fat
Pear obesity (Gynoid): lower body fat
Obesity: waist girth (values for men and women provided)

Location of Body Fat

Visceral Fat (abdominal fat), subcutaneous fat

Weight Management

Overweight/obesity
Underweight

Overweight and Obese (BMI) Canadian Adults (2021) Statistics

(Graph showing statistics, percentages)

Health Problems Associated with Obesity

Cardiovascular disease
Metabolic syndrome
Type 2 diabetes
Cancers (colon, breast, endometrial)
Gout
Gallbladder disease
Sleep apnea and respiratory problems
Bone and joint problems

Health Risks Associated with Excess Body Weight

General increase in risk for many diseases (blood pressure, LDL, triglycerides, HDL, type 2 diabetes).

Causes of Obesity

Energy in > Energy out
- Fat cell development
- Increase in kcal
- Portion sizes
- Inactivity
- TV watching
- Fat cell metabolism (thyroid function, LPL)
- Set point theory
- Genetics (leptin, ghrelin, adiponectin)

Fat Cell Development

Hyperplastic obesity (increase in number of fat cells)
Hypertrophic obesity (increase in size of fat cells) (Diagram explaining fat cell development from growth)

Other Possible Causes of Obesity

BMI increase over years
Energy intake has also been increasing
Physical Activity hasn't changed

Lifestyle and Rising Obesity Rates

(Graph showing percentages of increase for soft drinks, french fries, and cheeseburgers)

Regardless of Hunger

People typically overeat when there's abundance and variety.

Fat Cell Metabolism: Thyroid Function

Thyroid gland produces hormones (T4 - thyroxin, T3 - triiodothyronine)
Increases metabolism
Regulates protein, fat, and CHO catabolism

Fat Cell Metabolism: LPL

Lipoprotein lipase is an enzyme on fat cells promoting fat storage in fat and muscle cells.
Takes triglycerides from passing lipoproteins, hydrolyzes them, and passes fatty acids into the cell.
People with high LPL activity are good at storing fat.
Obese people have higher LPL activity than lean people.
LPL activity is regulated by sex hormones (higher in women). (location of fat)

LPL - Research Findings

LPL levels increased during weight loss.
Weight loss signals increase LPL activity/production.
May explain why obese people regain weight after loss.

Set Point Theory

Body maintains a set weight through internal controls that adjust metabolism. (Graph explaining concept)

Obesity Causes: Genetics

2 parents obese = 80% chance child becomes obese
1 parent obese = 50% chance child becomes obese

Obesity Causes: Genetics - Leptin

Acts as an "anti-obesity" hormone.
A protein produced by fat cells, affecting the hypothalamus.
Leptin amount is proportional to fat stores (more fat = more leptin).

Causes of Obesity - Leptin (Mechanism of Action)

Leptin affects food intake and energy expenditure by binding to leptin receptors in the hypothalamus.
Leptin inhibits hypothalamus peptides like neuropeptide Y (NPY increases appetite).

Leptin Resistance

Obese people may have high leptin levels but their energy balance doesn't shift negatively.

Mice Without and With Leptin (Experiment)

Mice with defective ob gene don't produce leptin = become obese.
Mice receiving leptin injections lose weight

Obesity: Gut Peptides

Many gut peptides regulate food intake.
Cholecystokinin (CCK), Peptide tyrosine tyrosine (PYY), Ghrelin, Glucagon-like peptide-1 (GLP-1)

Obesity: Gut Peptides - CCK

Dietary protein/fat in small intestine stimulate CCK release.
CCK binds to receptors, signaling hypothalamus to reduce food intake.

Obesity: Gut Peptides - PYY

Released by the small intestine after eating, suppressing food intake & appetite

Obesity: Gut Peptides - Ghrelin

Stimulates food intake.
Produced by stomach cells, stimulates growth hormone release, and increases hunger.

Obesity: Gut Peptides - Ghrelin (Blood Concentration)

(Diagram showing blood ghrelin concentration over 24 hours, lowest after meals)

Obesity: Gut Peptides - Ghrelin (Clinical Application)

Dieters who lose weight and resume normal eating often produce more ghrelin, counteracting weight loss efforts.
Obese people with gastric bypass surgery often have very little ghrelin.

Obesity: Gut Peptides - GLP-1 (Glucagon-Like Peptide-1)

Gut hormone activating GLP-1 receptors in pancreas, affecting glucagon/insulin release for blood glucose control

Obesity Treatment and Prevention

Diet and Exercise
Drug therapy
Surgery

Best for Weight Loss & Maintenance

Diet and increase physical activity (reducing Energy In and increasing Energy Out).

Obesity Treatment: Drug Therapy - Semaglutide

GLP-1 receptor agonist
Approved for type 2 diabetes and weight loss
Increases insulin, decreases glucagon.
Slows gastric emptying, reducing appetite. Injection under skin

Obesity Treatment: Drug Therapy - Semaglutide Considerations

Health Canada approved Wegovy, but not Ozempic for weight loss.
Physicians may prescribe either.
Approximate cost = $400/month
Side Effects: nausea, vomiting, heartburn, constipation, dizziness, fatigue

Gastric Surgery (Bariatric Surgery)

Adjustable Gastric Band Procedure
Roux-en-Y Type of Gastric Bypass Procedure

Weight Loss Strategies

Watch serving sizes
Reduce high-calorie foods (fat, sugar)
Don’t get too hungry (eat breakfast, increase fiber, veggies)
Engage in more physical activity if appetite increases

Diets, Diets Everywhere

Tips for differentiating fad/healthy diets while assessing weight loss efficacy (diet type planning, advantages and disadvantages).

Evaluating Weight-Loss Programs

Healthy vs. fad diets (criteria for distinguishing).

Health Risks of Underweight

Inability to preserve lean tissue during illness
Associated with osteoporosis and bone fractures.
Underweight females may have irregular menstrual cycles (amenorrhea), and/or difficulty conceiving.
Linked to poor-quality pregnancies and/or unhealthy babies

Eating Disorders

Anorexia Nervosa (distorted body image, amenorrhea, starvation)
Bulimia Nervosa (binge-purge cycle, over or normal weight )
Binge-Eating Disorder (BED; overconsumption without purging may be overweight or obese)
Eating Disorder Not Otherwise Specified (EDNOS)

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Description

This quiz explores the roles of various peptides and hormones in regulating food intake and appetite. You will answer questions about Cholecystokinin, leptin, GLP-1, and their effects on hunger and metabolic rates. Test your knowledge on the physiological mechanisms behind hunger and satiety.