Problem 6 1.4
Eating and hunger
Energy storage in the body
Energy is delivered in 3 forms:
- Lipids (fats)
- Amino acids (protein)
- Glucose (glycogen)
Most energy is stored as fats in adipose tissue, some is stored as glycogen in the liver
and some as proteins in our muscles
A gram of fat can store almost 2x as much energy as a gram of glycogen
Metabolism
Process of breaking down large molecules into simple energy-giving molecules
3 phases of energy metabolism
- Cephalic phase- prepatory phase, the sight, smell or thought of food. Blood
glucose increases which increases insulin release
- Absorptive phase- the energy from the food is absorbed into the bloodstream
and meets the body’s immediate energy needs. The increasing levels of
bloodborne fuels are minimised. Insulin helps glucose enter cells for use or
storage.
- Fasting phase- all energy not stored from the previous meal is used and the body
begins taking energy from reserves in order to meet immediate energy
requirements. Blood glucose levels and insulin levels decline. Glucagon release
increases which slows the return of hunger
Short term metabolism- composed of glycogen and used during the fasting phase
Long term metabolism- composed of fats, used when short term metabolism is
finished
Insulin
Promotes use of glucose as primary source of energy
Promotes conversion of bloodborne fuels to forms that can be stored
- Glucose to glycogen
- Fat/ amino acids to proteins
Promotes storage of glycogen in the liver/muscles. Fats stored in adipose tissue and
proteins stored in muscle
Glucagon
Converts glycogen into glucose
High levels of glucagon in fasting phase promotes the release of free fatty acids from
adipose tissue- primary fuel
Stimulates the conversion of fatty acids to ketones (used by muscles)
Hunger theories
Set point assumption- energy resources are assumed to be near a set point and
decline as the energy to fuel its physiological processes
Eating and hunger
Energy storage in the body
Energy is delivered in 3 forms:
- Lipids (fats)
- Amino acids (protein)
- Glucose (glycogen)
Most energy is stored as fats in adipose tissue, some is stored as glycogen in the liver
and some as proteins in our muscles
A gram of fat can store almost 2x as much energy as a gram of glycogen
Metabolism
Process of breaking down large molecules into simple energy-giving molecules
3 phases of energy metabolism
- Cephalic phase- prepatory phase, the sight, smell or thought of food. Blood
glucose increases which increases insulin release
- Absorptive phase- the energy from the food is absorbed into the bloodstream
and meets the body’s immediate energy needs. The increasing levels of
bloodborne fuels are minimised. Insulin helps glucose enter cells for use or
storage.
- Fasting phase- all energy not stored from the previous meal is used and the body
begins taking energy from reserves in order to meet immediate energy
requirements. Blood glucose levels and insulin levels decline. Glucagon release
increases which slows the return of hunger
Short term metabolism- composed of glycogen and used during the fasting phase
Long term metabolism- composed of fats, used when short term metabolism is
finished
Insulin
Promotes use of glucose as primary source of energy
Promotes conversion of bloodborne fuels to forms that can be stored
- Glucose to glycogen
- Fat/ amino acids to proteins
Promotes storage of glycogen in the liver/muscles. Fats stored in adipose tissue and
proteins stored in muscle
Glucagon
Converts glycogen into glucose
High levels of glucagon in fasting phase promotes the release of free fatty acids from
adipose tissue- primary fuel
Stimulates the conversion of fatty acids to ketones (used by muscles)
Hunger theories
Set point assumption- energy resources are assumed to be near a set point and
decline as the energy to fuel its physiological processes
