2. Question
What determines whether the energy in the foods you eat is used to fuel your body or stored for later use?
Amount of energy in the body
Hormones: insulin, glucagon, etc
Environments: fight/flight, emotions
Hypothalamus: hunger center of the brain

3. Energy Balance
~ go over handout ~

4. Energy Balance Energy intake & energy expenditure
Energy store = energy intake – energy expenditure
Negative energy balance
Results in weight loss, but not necessarily losing fat…
Positive energy balance
When is this favorable?
How does the body respond to each of the above?
Positive energy balance = taking in more; Negative energy balance = taking in less
A change in body weight is a useful INDICATOR of whether your are in positive or negative energy balance

5. Types of Adipose Tissues
Something you already know:
Adipocytes make up adipose tissues
Visceral adipose tissue (VAT)
protect & support body organs
Subcutaneous adipose tissue (SCAT)
Insulation – body temperature

7. Functions of Adipose Tissues
More functions:
Vitamin A, D, E, K absorption
Cell membrane
Transportation (lipoprotein)
Communication (PPAR) – Adipokines
Adipose tissues are considered as one of the largest endocrine organ in the body

8. Growth of Adipose Tissue
Something new:
Hypertrophic growth
Hyperplastic growth
Adipose tissues is the source of several hormones, it plays an active role in regulating energy balance. The discovery that adipocytes are a source of hormones and hormone-like substances collectively called adipokines, had led many researchers to consider adipose tissue to be the largest endocrine organ in the body.

9. Question What makes you eat? Why you make certain food choices?
Hunger, mood, social norm, boredom, etc.
Taste, health, religion, cultural, env, peer pressure, etc.
Many facets of your life
Numerous purposes beyond providing energy
Psychological, physical, social, and cultural forces

10. Physiological Influence on Energy Intake
Hunger & Satiety

11. Hypothalamus Communications between body organs
sending and receiving signals
Releases neuropeptides (brain proteins)
catabolic & anabolic
Factors influencing hunger and satiety
Gastric stretching (digestive sys)
Circulating nutrient level (circulatory sys)
GI hormones (endocrine sys)
CNS

12. Gastric Stretching Mechanorecepters  neurotransmitters  brain
Size of stomach
High-volume food: liquid & fiber
Bariatric surgery
Surgeries involved in losing weight
Gastric banding
Gastric bypass

13. Bariatric Surgery Bariatric Surgery pg 348
Bariatric Surgery pg 348

14. Blood Nutrient Concentration
Chemoreceptors  neurotransmitters  brain
Glucose
The brain is sensitive to blood glucose level
Amino acids
stimulate the release catabolic neurotransmitters
Tryptophan is used to synthesize serotonin
Lipids
weaker affect because easily overcome by tasty flavor
Tryptophan-rich foods make you happy and sleepy

15. GI Hormones Decrease intake: CCK Decrease intake: PYY
small intestine
protein and fatty acids (so the pancreas releases pancreatic enzymes)
Decrease intake: PYY
small & large intestine
food
Increase intake: ghrelin
Stomach
Prior to a meal
There are other GI hormones, but you need to know only the three mentioned above.

16. Psychological Influence on Energy Intake
Appetite

17. Food Aversion & Food Craving
Sensory factors: taste, smell, appearance, etc.
Emotional states: fear, depression, disappointment, excitement, stress, etc
Strong psychological factors
 eating disorders

18. + and – energy balance physiological psychological TEE VAT & SCAT
Adipokines (PPAR)
Hyperplastic & hypertrophic growth
physiological
Hunger & satiety
Gastric stretching (bariatric surgeries)
Nutrients in the blood (tryptophan  serotonin)
Gi hormones (CCK, PYY, ghrelin, insulin, glucagon)
Hypothalamus (neuropeptides)
psychological
Food aversion and craving (appetite)
Social aspects in eating
TEE

19. 19

20. Total Energy Expenditure

21. Total Energy Expenditure (TEE)
Basal metabolism
Physical activity
Thermic effect of food
Adaptive thermogenesis
Nonexercise activity thermogenesis
relatively small

22. Basal Metabolism Accounts for most of TEE (50-70%)
Sustain basic, involuntary life functions
BMR = kcal/hour & BEE = kcal/day
not including food processing & physcial activity
Stringent conditions
RMR = kcal/hour & REE = kcal/day
Usually 10% higher than BMR/BEE

23. Harris-Benedict Equation
Estimating REE
Male
[13.8 x weight (kg)] + [5 x height (cm)] + [6.8 x age]
Female
[9.6 x weight (kg)] + [1.8 x height (cm)] + [4.7 x age]
Note that this is just an estimation and may not apply to every individual. Why not?

24. Factors Affecting BMR Age Sex Growth Body weight Body shape
Body composition
Body temperature
Stress
Pregnancy
Lactation
Energy/Food restriction

25. Physical Activity Accounts for 15-30% of TEE
Amount of physical activity: sedentary vs. active
Type of physical activity
Body size

26. Thermic Effect of Food (TEF)
Account for the least amount of TEE (5-10%)
Food process - energy used to digest, absorb, transport, metabolize, and store nutrients
Influenced by the amount and type of food we eat
protein foods have high TEF
fatty foods have low TEF

27. Measuring TEE
Accurate measurements require expensive equipments and high degree of expertise
Direct calorimetry – measures body heat
~60% of energy/glucose is released as body heat
Indirect calorimetry – measures O2 intake and CO2 output
1L of O2 is used to metabolize 4.8kcal of nutrients
IOM developed EER as part of DRI