This document discusses nutrition and energy balance in the human body. It defines a balanced diet as one containing proper proportions of carbohydrates, fats, proteins, vitamins, minerals, and water for good health. The three macronutrients that provide energy are carbohydrates, proteins, and fats, while vitamins and minerals are called micronutrients. The basal metabolic rate accounts for 60% of the total daily energy expenditure in the body and represents the calories needed for basic functioning even at rest. Other factors like physical activity and food digestion account for the remaining calories expended daily.

1. Nutrition
Introduction, Balanced Diet, Calorie,
Caloric Value, Energy Content of
Food, Use of Food Energy, BMR
Source: Lippincott Biochemistry
Chatterje Biochemistry
Maryam Fida (o-1827)

2. Introduction
• Nutrition is important
• A hungry man is an angry man
• Nutritional problem is usually question of protein
esp. Proteins derived from animal sources
• Vegetables/Grains sources contain enough
calories but proteins are of low biological value
• Foods are wrongly classified as hot or cold

3. Balanced Diet
Definition:
A diet that contains the proper proportions of
carbohydrates, fats, proteins, vitamins, minerals, and
water necessary to maintain good health

4. Major food groups
• Milk Group
• Meat Group
• Fruit Group
• Vegetables Group
• Bread Group

5. Macronutrients
Micronutrients

6. • All energy is provided by three classes of nutrients
called Macronutrients
• Carbohydrates
• Proteins
• Fats
Vitamins and minerals - Micronutrients

7. Dietary Reference Intake (DRI)
• DRI: Estimates the amounts of nutrients
required to prevent deficiencies and maintain
optimal health and growth
• Incorporates upper limits on consumption of
nutrients

9. RDA:
• Average daily dietary intake level that is
sufficient to meet the nutrient requirements
for nearly all (97-98%) the individuals in a life
stage and gender group

10. • Calorie: amount of heat required to raise the
temperature of 1 gm of water by 1oC
(specifically from 15-16oC)
• Kilocalorie = 1000 calories

11. Caloric Value
• Amount of heat- energy obtained by burning
1.0 gm of food stuff completely in the
presence of O2
• Determined in vitro in a special apparatus
called “Bomb Calorimeter”
• Caloric values of carbs and proteins is 4.0
kcal/gm. And 9.0 kcal/gm for fats

12. Energy content of food
Average energy available from the major food components
1 cal = 4.2 J 1kCal/ Cal = 4.2kJ

13. Use of food energy in the body
1. Basal Metabolic Rate (BMR) or Resting
metabolic rate (60%)
2. Physical activity (30%)
3. Thermic effect of food (10%)
The number of calories expended by these
processes in a 24-hour period is the Total
Energy Expenditure (TEE)

14. Basal Metabolic Rate
(BMR)
Also called
Resting
Metabolic
Rate
(RMR)
Estimated total energy expenditure in a typical 20-year-old woman, 165 cm (5 feet, 4
inches) tall, weighing 50 kg (110 lb), and engaged in light activity.
Daily Energy Expenditure in a Sedentary Individual

15. • An average woman needs to eat about 2000
calories per day to maintain weight
• An average man needs 2500 calories to
maintain weight

16. BMR
Definition:
Calories utilized by an individual who is awake but
at complete rest both mentally and physically to
maintain respiration, circulation, muscle tone,
functions of viscera like kidney, liver and brain and
for the maintenance of body temperature

17. Conditions that need to be fulfilled before
calculating BMR
1. Awake but at complete rest both mentally and
physically
2. Fasting (12-18 hours) i.e. in the post-absorptive state.
This period is allowed to pass for avoiding:
a) Effects of digestion and absorption
b) Effects of Specific Dynamic Action of Food(SDA) of
foodstuffs
3. Recumbent/reclining position in bed
4. Under normal conditions of environment i.e. normal
temp. (20-25oC) pressure and humidity

18. Factors Influencing BMR
• Age: Higher in children than in adults
• Sex: Females lower BMR than men
• Surface area: BMR is directly proportional to
surface area
• Climate: In colder climates BMR is high
• Racial Variations: Eskimos have 33% above
normal BMR
• State of Nutrition: BMR is lowered in conditions
of malnutrition, starvation and wasting disease

19. • Body temp: BMR increases by 12% for every
1oC rise in temp
• Drugs: Caffeine, nicotine, alcohol increase.
Anesthetics decreases BMR

20. Clinical aspect
Pathological variations:
• Fever increases BMR
• Diseases: Characterized by increased activity
of cells, increase heat production and BMR
e.g. leukemias
• Endocrine disease: Hyperthyroidism increases,
hypothyroidism decreases

21. Importance
• As a diagnostic aid: e.g. in thyroid diseases
• Effect of food and drugs

22. Respiratory Quotient (R.Q.)
• Ratio of the of volume of CO2 produced from
the body to the volume of O2 consumed per
unit time
• RQ = CO2 eliminated / O2 consumed
• RQ of CHO is 1
• RQ of Fat 0.7
• RQ of Proteins is 0.82