Lecture 1 Nutrition and body weight

Living cells require energy for:

Biosynthetic work-synthesis of cellular components.
Transport work across cell membranes-.
Mechanical work-
Electrical work-
Osmotic work-kidney
.
The Joule (J) is the unit of energy now widely used in countries other than the USA. However, the term calorie (1 cal = 4.184 Joules) is still used in the medical literature and is more generally understood by patients. In metabolism energy changes are often expressed in terms of kJ or kcal where 1 kJ = 1,000 Joules and 1 kcal=1000 calories. Energy exists in many forms: thermal, light, mechanical, electrical, osmotic and chemical,

Daily Energy Expenditure
. This daily energy expenditure has three components:

i)energy to support our basal metabolism-Basal Metabolic Rate (BMR)

ii)energy for voluntary physical activities.

iii)energy required to process the food we eat (diet-induced thermo genesis

i) Basal Metabolic Rate (BMR(
The BMR is a measure of the basal energy required to maintain life-the functioning of the various tissues of the body at physical, digestive and emotional rest. The major tissues contributing to the BMR are:
skeletal muscles,
central nervous system,
liver
heart.