Normal and Therapeutic Nutrition

Normal and Therapeutic Nutrition 3(2+1)

Lesson 2:Factors influencing food intake and food habits

Hunger

Defined as “that set of internal signals that stimulate the acquisition and consumption of food” (Figure)

Theories on role of nutrients in hunger and satiety
Several theories have been proposed concerning the role of nutrients in hunger and satiety

Glucostatic Theory (Mayer 1966)

• Chemoreceptors in the ventromedial center of hypothalamus have an affinity for glucose and are activated by it.
• When the glucose utilisation is high, these receptors act as a brake on lateral nucleus so that feeding ceases.
• When glucose utilisation is low, there is no stimulation of receptor in the ventromedial center and the hunger causes the animal to eat.

Lipostatic Theory
A metabolite, such as enzyme lipoprotein lipase circulating in blood, is linked to hypothalamus to establish a set point that determines calorie intake. This set point can be readjusted from time to time to new levels of adipose tissue.

Aminostatic Theory
The level of amino acids in the circulation can determine the initiation or cessation of hunger.

Thermostatic Theory (Brobeck – 1948)
Animals that are exposed to cold increase their intake of food. Animals that are in warm environment decrease their intake of food.