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BHM 201

Food Science & Nutrition

TU BHM · Semester 3 · Recent BHM syllabus series

Requirement
required
Credits
3
Study Guide
8 units available

Chapter notes

Authoritative study guide across 8 syllabus units

Open a unit to read its study notes.

Unit 1: Introduction to Food· 5 LHs· ~6 marks

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Pass path: Memorize must-know definitions, operational roles, and core terminology of Food Science, Nutrients, and Basal Metabolic Rate. Top path: Master advanced exam requirements: diagram and execute the Total Daily Energy Expenditure (TDEE) Architecture and accurately contrast Macronutrients vs Micronutrients, resolving TU board problem scenarios with complete working steps.

Part 1: Core Concepts (2 Marks)

  • Food Science: The multidisciplinary study of the biological, physical, and chemical makeup of food, and the underlying concepts of food processing, safety, and deterioration.
  • Nutrients: Chemical substances present in food essential for body growth, tissue repair, energy provision, and normal physiological metabolic maintenance, categorized into Macronutrients (Carbohydrates, Proteins, Fats) and Micronutrients (Vitamins, Minerals).
  • Basal Metabolic Rate (BMR): The minimum rate of energy expenditure required by a warm-blooded animal at complete physical, digestive, and emotional rest at comfortable room temperature to maintain vital involuntary life functions (breathing, heart circulation, cellular homeostasis).
  • Physiological Fuel Values (Atwater Factors):
    • Carbohydrates: 4 kcal/g4\text{ kcal/g} (16.7 kJ/g16.7\text{ kJ/g})
    • Proteins: 4 kcal/g4\text{ kcal/g} (16.7 kJ/g16.7\text{ kJ/g})
    • Lipids (Fats): 9 kcal/g9\text{ kcal/g} (37.7 kJ/g37.7\text{ kJ/g})
    • Alcohol: 7 kcal/g7\text{ kcal/g} (29.3 kJ/g29.3\text{ kJ/g})

Part 2: Structural Frameworks (10 Marks)

Total Daily Energy Expenditure (TDEE) Architecture

TOTAL DAILY ENERGY EXPENDITURE (TDEE)

1. Basal Metabolic Rate (BMR) 60% - 75% of total energy
(Cellular metabolism, respiration, brain)
2. Physical Activity Level (PAL) 15% - 30% of total energy
(Occupational labor, walking, exercise)
3. Thermic Effect of Food (TEF) 8% - 10% of total energy
(Metabolic cost of digestion & absorption)

Factors Influencing Basal Metabolic Rate (BMR):

  1. Body Composition: Muscle tissue consumes significantly more metabolic energy at rest than adipose fat tissue; higher lean muscle mass increases BMR.
  2. Age & Gender: BMR is highest during infancy and puberty; declines by 2−5%2-5\% per decade after age 30. Males typically have 5−10%5-10\% higher BMR than females due to greater testosterone-driven muscle mass.
  3. Thyroid Hormone: Thyroxine (T4T_4) and Triiodothyronine (T3T_3) directly regulate cellular respiration; hyperthyroidism spikes BMR, while hypothyroidism depresses BMR.
  4. Fever & Ambient Temperature: Body temperature elevation of 1∘C1^\circ\text{C} increases BMR by approximately 13%13\%.

Part 3: Distinction Tables

Basis of Comparison Macronutrients Micronutrients
Dietary Requirement Required in large daily quantities (tens or hundreds of grams) Required in minute quantities (milligrams or micrograms)
Energy Provision Yields direct metabolic energy (4 to 9 kcal/g4\text{ to }9\text{ kcal/g}) Yields zero direct calories; acts as metabolic co-factors
Constituents Carbohydrates, Proteins, Lipids, Water Fat-soluble & Water-soluble Vitamins, Minerals
Deficiency Onset Muscle wasting, emaciation, marasmus within weeks Specific clinical deficiency syndromes (scurvy, rickets)

Part 4: Worked Problems & Exam Traps

Typical TU Board Examination Problem:

A hotel breakfast buffet plate contains 60 grams of carbohydrates, 25 grams of protein, and 20 grams of fat. Calculate:

  1. The total physiological energy yield in kilocalories (kcal).
  2. The total energy yield converted into kilojoules (kJ), using 1 kcal=4.184 kJ1\text{ kcal} = 4.184\text{ kJ}.
  3. The percentage contribution of fat to total calories.

Model Solution:

  1. Caloric Energy Yield:
    Energy from Carbohydrates=60 g×4 kcal/g=240 kcal\text{Energy from Carbohydrates} = 60\text{ g} \times 4\text{ kcal/g} = 240\text{ kcal}
    Energy from Protein=25 g×4 kcal/g=100 kcal\text{Energy from Protein} = 25\text{ g} \times 4\text{ kcal/g} = 100\text{ kcal}
    Energy from Fat=20 g×9 kcal/g=180 kcal\text{Energy from Fat} = 20\text{ g} \times 9\text{ kcal/g} = 180\text{ kcal}
    Total Caloric Energy=240+100+180=520 kcal\text{Total Caloric Energy} = 240 + 100 + 180 = \mathbf{520 \text{ kcal}}
  2. Energy Yield in Kilojoules (kJ):
    Energy in kJ=520 kcal×4.184 kJ/kcal=2,175.68 kJ\text{Energy in kJ} = 520\text{ kcal} \times 4.184\text{ kJ/kcal} = \mathbf{2,175.68 \text{ kJ}}
  3. Percentage Contribution of Fat:
    Fat Energy %=(180 kcal520 kcal)×100=34.62%\text{Fat Energy \%} = \left( \frac{180\text{ kcal}}{520\text{ kcal}} \right) \times 100 = \mathbf{34.62\%}

TU Exam Trap: Using 4 kcal/g4\text{ kcal/g} for fat instead of 9 kcal/g9\text{ kcal/g}. Fat is an energy-dense nutrient yielding more than double the caloric density of protein or carbohydrate!

Students lose marks here because they make errors by using 4 kcal/g4\text{ kcal/g} for fat instead of 9 kcal/g9\text{ kcal/g}. Fat is an energy-dense nutrient yielding more than double the caloric density of protein or carbohydrate.