Metabolism - Energy Balance: Flashcards
1
Q
Body Weight Regulation
A
The long-term balance of body weight is achieved through a highly complex network of regulatory systems.
2
Q
Energy Balance
A
- On average, a person consumes approximately one million calories per year.
- Despite this huge intake we maintain a balance with how much energy we expend.
- The control of this mechanism is very precise.
- If energy intake chronically exceeds energy expenditure by just 25kcal per day, this results in morbid obesity
3
Q
1st Law of Thermodynamics
A
- Energy represents the capacity of a system to perform work.
1. There are different forms of energy – chemical, mechanical, electrical – all of which can be converted to heat.
2. ‘First Law of Thermodynamics’: Energy cannot be created or destroyed, but it can be transformed from one form into another.
3. Plants depend on energy captured from the sun to synthesise proteins, carbohydrates and fats.
4. Animals meet their energy needs from chemical energy stored in plants and other animals.
4
Q
Energy Uses
A
- The chemical energy obtained from food is used to perform:
1. Chemical work (synthesis of new macromolecules).
2. Mechanical work (muscular contraction).
3. Electrical work (maintenance of ionic gradients across membranes; e.g. the sodium-potassium pump).
5
Q
Energy Balance
A
- Energy balance = energy intake (+ energy stores) – energy expenditure.
- If the intake and expenditure are not equal:
1. Negative energy balance (utilisation of body’s energy stores: glycogen, fat, protein).
2. Positive energy balance (an increase in body energy stores, primarily as fat).
6
Q
Energy Balance
A
- Energy consumed in the form of food and drinks can be stored as:
1. Glycogen in the liver and muscles.
2. Fat (accounting for the majority of energy storage). - When energy is in short supply the body can source energy from:
1. Glycogen in the liver and muscles.
2. Fat
3. Protein (a last resort in cases of starvation or malnutrition – amino acids are liberated from tissues such as skeletal muscle).
7
Q
2nd Law of Thermodynamics
A
- Second Law of Thermodynamics: All energy used by the body degenerates as heat.
1. i.e. Whenever energy is transferred or transformed (e.g. during cellular metabolic reactions) there is a loss of energy in the form of heat.
2. When food is utilised in the body (for chemical, mechanical or electrical work), this is always accompanied by the loss of some energy in the form of heat (i.e. thermal energy that is no longer available for work inside the body).
8
Q
Calories
A
- The heat-generating potential of a food can be measured and expressed as energy units known as ‘calories’.
- In a nutritional context, when people say ‘calories’ they are usually referring to ‘kilocalories’ (1,000cal = 1kcal).
- Modern society has historically placed more emphasis on the calorie content of a food than the nutrient content of a food.
Calorie= the amount of heat required to raise the temperature of 1g of water by 1°C
9
Q
Energy in Macronutrients
A
- Different macronutrients provide different amounts of energy:
1. 1g Carbohydrate = 4 kcal
2. 1g Protein = 4 kcal
3. 1g Fat = 9 kcal
4. 1g Alcohol = 7 Kcal
5. 1g Fibre (yielded from bacterial fermentation in the gut) = 2 kcal
10
Q
Mitochondria & ATP
A
- All life relies on ATP (adenosine triphosphate) as the energy ‘currency’ used to fuel cell processes.
- Mitochondria generate ATP through Acetyl CoA formation, the Krebs Cycle and the Electron Transport Chain.
- The key nutrients needed to fuel these include: Magnesium, Manganese, Iron, Sulphur, CoQ10, Copper, Vitamin B1, B2, B3, B5 and alpha-lipoic acid.
- Nutrient deficiencies, toxins (including poor liver detoxification and elimination pathways) and heavy metals (e.g. Mercury, Arsenic & Aluminium) can damage mitochondria and interfere with energy production.
Mitochondria = the organelles responsible for energy (ATP) production
11
Q
Energy Production
A
- We should address all factors that contribute to ATP production.
Impairment of any can result in deficiency (e.g. fatigue).
1. Sufficient nutrient intake (fuel)
2. Digestion & absorption
3. Respiratory (i.e. lung) health
4. Heart & circulation health
5. Mitochondrial health
6. Thyroid health
7. Adrenal health
8. Healthy Detoxification
9. Sleep hygiene
12
Q
Energy Production: Sufficient nutrient intake (fuel)
A
- Sufficient nutrient intake (fuel): Nutrient intake is crucial for cell respiration (i.e. for the Krebs cycle etc.) – so ensure good nutrition.
13
Q
Energy Production: Digestion & absorption
A
- Digestion & absorption: Digestion is crucial for the liberation of nutrients from food. Good GI health is also vital for nutrient absorption.
14
Q
Energy Production: Respiratory health
A
- Respiratory (i.e. lung) health: Oxygen intake. Consider lung diseases, smoking, chronic hyperventilation.
15
Q
Energy Production: Heart & circulation health
A
- Heart & circulation health: Key in nutrient (‘fuel’) delivery to cells.
