Physiological Factors

Physiological factors affect the body's need and desire for food.

HUNGER:

Hunger is controlled by a small gland in the base of the brain called the hypothalamus. The hypothalamus has a number of functions in the body and works closely with the pituitary gland to:

Control body temperature.
Regulate appetite, thirst and body fluids.
Induce sleep and wakefulness.
Control the release of growth and sex hormones from various glands throughout the body.

APPETITE:

Appetite is the desire for food even when the body is not hungry. Appetite can be triggered by:

The sight of appetising food
Aroma
Even the mention of food in conversation

Unlike hunger, if appetite is not satisfied it will eventually go away.

SATIETY:

The feeling of fullness that comes with eating adequate amounts of food. The body digests foods at differing rates. Slow moving foods have a higher satiety value.

Download this poster and print it to put up in your bedroom so you'll always remember the satiety values of foods.

Nutritional requirements

BODY SIZE/TYPE and HEREDITY:

Those with a smaller body size require less protein for the maintenance and repair of body tissues because their body mass is less. Body type is identified by:

Skeleton size (height and overall size of the body frame)
Amount of body fat
Weight
Amount of muscle

You may be endomorph, mesomorph and ectomorph.

AGE:

Nutrients carry out specific functions within the body, the amount of nutrients needed by an individual is regulated by the growth processes:

3 - 19 years- more calcium + protein for growth and bones and tissues + carbohydrates for energy.

20 to 40-50 years- genetically predetermined height and build achieved, muscle tone and amount of fatty tissue varies, depending on diet and exercise.

40 + years- BMR slows down, intake of energy rich foods needs to be lowered and exercise increased for the ‘middle age spread’ commonly occurs.

LEVEL of ACTIVITY:

The more physically active you are, the more energy rich foods you must eat. A sedentary person requires less of all nutrients than an active person.

SEDENTARY PERSON: Needs less energy to avoid adipose tissue. Needs less protein as maintenance of muscle tissue is lower. A sedentary person is someone who doesn't move much.

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GENDER:

WOMEN: Menstruation and childbirth may mean that women require a higher dietary intake of iron and calcium. Extra adipose tissue is often stored on upper arms, bust, waist, hips and thighs, buttocks- can become more pear shaped.

MEN: Having a greater proportion of muscle men require more protein. Extra adipose tissue usually can build up around the waist and midriff region and become more apple shaped.

HEALTH STATUS: Download the fact sheets:

Diseases may be related to poor diet include:

Beri-beri

Ricketts

Scurvy

Osteoporosis

Pellagra

Anaemia.

Some diseases may require people to eat differently, for example high cholesterol, lower foods with saturated fat.

PREGNANCY AND LACTATION:

The nutrient needs of a pregnant woman will obviously increase because the foetus shares the nutrients supplied in the mothers bloodstream. Pregnant women should eat a variety of nutritious foods daily, including:

Bread, cereals, rice, pasta and noodles (wholegrain and wholemeal is best)
Vegetables and legumes (plants that bear their seeds in a double-seamed pod such as peas, beans, lentils, soy beans and peanuts)
Fruit
Milk, yoghurt and hard cheese (low fat preferred)
Meat, fish, poultry, cooked eggs and nuts.
Folic acid supplements to prevent birth abnormalities such as spina bifida prior to conception.
Foods that are naturally rich in folate
Calcium
Iron

7 foods to eat whilst pregnant

Download & complete question sheet

Reactions to Food

COLOUR

Colour can indicate the foods quality and nutritional value. Fruits and vegetables display their most desirable colours when they are their peak. As fruit and veg becomes over-ripe their turgor (crispness) and nutritive values decrease.

Pink and blue can be used for kerosene as they do not naturally occur in nature.

SHAPE

Shape and portion control can assist consumers to make a food choice. Softer shapes can have a more comfortable mouthfeel.

TURGOR

Wilted spinach and soft vegetables have lost some of their turgor. Textural differences in foods create interest in meals and stimulate the appetite.

FLAVOUR:

Young children have a good sense of taste and do not need foods to be highly flavoured to be acceptable. Ageing adults have decreased sensitivity to taste and may compensate by eating highly spiced, salted or sweetened foods.

To be tasted, the flavouring substance must be dissolved in a liquid, it may be present in the food or provided by saliva in the mouth. Dry mouth, which can come from some medications will result in less ability to taste.

AROMA:

Describes how something smells. In our nose there are odour receptor nerves which transmit signals to the hypothalamus in the brain. Taste and aroma are related. It can indicate a lack of freshness as in sour milk or ripeness in a pineapple.

ALLERGIES:

Some people’s food choices are limited because they have a physical reaction to specific foods or ingredients. They may have to read labels as they want to avoid abdominal swelling, vomiting, diarrhoea , itches, rashes. Common foods which can cause food allergies are cow’s milk, shellfish, eggs, peanuts, wheat and soy.

Factors Affecting Food Selection