Energy Metabolism, Food Intake and Weight Loss Flashcards
What is the result of energy intake chronically exceeding energy expenditure by just 25kcal per day?
Morbid obesity
What are the different forms of energy?
Chemical, Mechanical, Electrical
All of which can be converted to heat
What is the ‘FIrst Law of Thermodynamics’?
Energy cannot be created or destroyed, but it can be transformed from one form into another.
Give an example of chemical work?
Synthesis of new macromolecules
Give an example of mechanical work
Muscular contraction
Give an example of electrical work
Maintenance of ionic gradients across membranes; eg the sodium-potassium pump.
What is the formula for energy balance?
ENERGY BALANCE = energy intake (+ energy stores) - energy expenditure
What is negative energy balance?
Utilisation of the body’s energy stores: glycogen, fat, protein.
What is positive energy balance?
An increase in body energy stores, primarily as fat.
What is energy consumed in the form of food and drinks stored as?
- Glycogen in the liver and muscles
- Fat (accounting for majority of energy storage)
When energy is in short supply, where can the body source energy from?
- Glycogen in liver and muscles
- Fat
- Protein (last resort- cases or starvation or malnutrition)
What is the 2nd Law of Thermodynamics?
All energy used by the body degenerates as heat.
ie Whenever energy is transferred or transformed (eg during cellular metabolic reactions) there is a loss of energy in the form of heat.
What is a calorie?
The amount of heat required to raise the temperature of 1g of water by 1 degree celsius
How many calories are in
a) 1g Carbohydrate
b) 1g Protein
c) 1g Fat
d) 1g Alcohol
e) 1g Fibre
a) 4 kcal
b) 4kcal
c) 9kcal
d) 7kcal
e) 2kcal
What is the energy ‘currency’ used to fuel cell processes?
ATP (Adenosine Triphosphate)
What is the name of the organelles responsible for energy (ATP) production?
Mitochondria
What are the key nutrients (cofactors) needed to fuel ATP generation via Acetyl CoA formation, Krebs Cycle and Electron Transport Chain?
Magnesium Manganese Iron Sulphur CoQ10 Copper B1, B2, B3, B5 Alpha-lipoic acid
Name 5 factors that contribute to ATP production
- Sufficient nutrient intake
- Digestion & Absorption
- Mitochondrial Health
- Thyroid health
- Healthy Detoxification
What does BMR stand for and what is it?
Basal Metabolic Rate
It is the minimum level of energy required to sustain life
Name 4 factors that affect BMR
- Age
- Stress
- Fever
- Caffeine
What nutrient deficiencies may lead to hypothyroidism?
Iodine, Selenium, Zinc, Vitamin D,
What is the Thermic Effect of Food (TEF)?
TEF is the amount of energy required to digest and process the food you eat.
What are the Thermal effects of fats, carbs and proteins?
Fats = 0 - 3% Carbohydrates = 5 - 10% Proteins = 20-30%
What is de novo lipogenesis (DNL)?
The metabolic pathway that synthesises fatty acids from excess carbohydrates
What diseases may benefit from a Ketogenic diet?
Obesity, metabolic syndrome, type 2 diabetes, Alzheimer’s, Parkinson’s and certain cancers.
Effective in preventing epileptic seizures
What are the following digested into?
Carbohydrates
Proteins
Fats
Carbohydrates -> Glucose
Proteins -> Amino Acids
Fats -> Fatty acids
Name 8 of the hormones/neurotransmitters which affect food intake and state if they increase or decrease appetite.
Neuropeptide Y (NPY) - increases appetite
Cholecystokinin (CCK) - decreases appetite
Insulin - decreases appetite
Glucagon - decreases appetite
Glucagon-like peptide 1 (GLP-1) - decreases appetite
Bombesin - decreases appetite
Ghrelin - increases appetite
Leptin - decreases appetite
Why is CCK secreted?
It is secreted in the response to food in the duodenum.
Meals rich in protein and fat stimulate CCK more than meals that just contain carbohydrates.
What is the role of insulin in the body?
- To lower blood glucose by storing in the muscle tissue and liver as glycogen
- It is responsible for controlling the storage and release of fatty acids. Fat cannot be stored without insulin.
How is storage and release of fatty acids achieved?
- The regulation of several lipases enzymes
2. The activation of glucose transport into the fat cells via recruitment of glucose-transport protein 4 (GLUT4)
Name the roles/metabolic actions of insulin in the body
- Stimulates synthesis of triglycerides from free fatty acids
- Increases synthesis of liver glycogen
- Inhibits gluconeogenesis
- Stimulates glucose uptake in skeletal muscle
- Reduces hunger via hypothalamus
What is gluconeogenesis?
The biosynthesis of glucose from non-glucose precursors
What is a typical feature of insulin resistance and what are the side effects of this?
Central adiposity is a typical feature and can produce inflammatory cytokines, promoting further hormone resistance, obesity and chronic diseases.
How does the liver metabolise fructose differently to glucose?
When glycogen stores are full, fructose is converted directly to liver fat.
This can lead to NAFLD, obesity, gout
What factors can impact ghrelin secretions?
Dysregulated sleep and elevated cortisol can increase secretions
Exercise has been shown to decrease them
What are some effects of Leptin Resistance?
Excess leptin can modify insulin sensitivity, tissue metabolism, stress responses and reproductive function.
Leptin resistance leads to failure of suppressing the appetite
Name some factors that can increase leptin sensitivity:
- Go Gluten-free
- Reduce sugar consumption
- Support gut flora with probiotics
- Reduce inflammation
- Regular exercise
- Sleep hygiene
List 4 functions of prebiotics in Energy Metabolism
- Promote satiety
- Reduce hunger
- Reduce food ingestion
- Suppress ghrelin
What are prebiotics?
A non-digestible carbohydrate. that promotes the growth of beneficial gut bacteria.
What are probiotics?
Microorganisms introduced into the body for their beneficial health properties.
What are some factors affecting food intake?
- Cultural/social - meal patterns, religious traditions, attitude to food left on plate
- Sensory - appearance/ smell of food, packaging/advertising, addiction
- Emotional - stress, sadness, loneliness
- Other - hormones, disease states, medications, cost
What strategies may help maintain stable blood sugars?
- Include protein with every meal
- Avoid refined carbs/sugar and include more complex carbs/low GI foods
- Choose organic/whole foods
- Chew well, eat mindfully, don’t overeat, 3 meals a day
Name 5 factors that can hinder weight loss
- Overeating and junk food
- Sedentary lifestyle
- High blood sugar
- Chronic stress
- Poor sleep
What is EPOC?
Excess Post-exercise Oxygen Consumption - oxygen intake increases post exercise.
Explain what oxygen debt means.
This is when an activity performed uses energy faster than the rate at which the body can supply oxygen.
