Unit 8
Metabolism of Nutrients and Energy Balance

In this unit, we examine the energy value of foods and the energy expenditure of humans. We discuss the challenges of assessing body weight and determining whether a person is underweight or overweight. Finally, we discuss the effects on the body of feasting, fasting, and following a carbohydrate-restricted diet. In Unit 11 we will deal with the consequences of excess weight and safe weight-loss strategies.

Objectives

After completing this unit, you should be able to

1. explain how the body deals with an energy intake above or below requirements.
2. define food energy value, and state the physiological fuel values of protein, carbohydrate, fat, and alcohol.
3. define basal metabolism, basal metabolic rate (BMR), voluntary activities, and the thermic effect of food.
4. state the energy value of one pound (about 0.5 kg) of body fat.
5. discuss the influences of BMR, voluntary activities, and the thermic effect of food on energy expenditure.
6. explain the anthropometric measures listed below, and discuss their strengths and weaknesses.
   • body mass index (BMI)
   • per cent of body fat
   • waist measurement
7. calculate BMI and define underweight, normal weight, overweight, and obese.
8. discuss the health hazards associated with being underweight.
9. explain the metabolic events that occur during feasting and fasting.