Body Composition, Energy Needs & Nutritional Health Factors

Posted on May 3, 2025 in Biology

Body Mass Index (BMI)

Formula: BMI = Weight (kg) / Height (m)²

BMI Categories:

  • 18.5 – 24.9: Normal weight
  • 25.0 – 29.9: Overweight
  • 30.0 – 39.9: Obese
  • 40.0+: Very Obese (Morbidly Obese)

Waist Circumference & Health Risks

Measure around the smallest part of the waist.

Risk Thresholds (Waist Circumference):

  • Men: Increased risk > 94 cm; High risk > 102 cm
  • Women: Increased risk > 80 cm; High risk > 88 cm

Associated Health Risks:

  • Diabetes (Type II)
  • Non-communicable diseases (e.g., cardiovascular disease)

Ideal Body Weight (IBW)

Approximate Formula: IBW (kg) = Height (cm) – 100

Note: This is a simplified formula. Adjustments are often needed (e.g., +/- 10% for men, +/- 15% for women based on frame size).

IBW Categories (% of IBW):

  • > 120%: Obesity
  • 110-120%: Overweight
  • 90-110%: Normal weight
  • < 90%: Underweight
  • < 70%: Severe underweight

Energy Balance

  • Negative Balance (-): Energy Intake < Energy Output = Weight loss
  • Positive Balance (+): Energy Intake > Energy Output = Weight gain

Note: Managing energy balance is crucial for weight management and conditions like Type 2 Diabetes Mellitus (DM2). Diet composition (e.g., high-fat/low-fat) also plays a role.

Daily Energy Requirement (DER)

Formula: DER = BEE (Basal Energy Expenditure) x Activity Coefficient (C)

BEE is often estimated using Basal Metabolic Rate (BMR) formulas like the Harris-Benedict equation:

BEE/BMR Formulas (Harris-Benedict):

  • Men: BEE = 66.47 + (13.75 x Weight in kg) + (5.0 x Height in cm) – (6.76 x Age in years)
  • Women: BEE = 655.1 + (9.56 x Weight in kg) + (1.85 x Height in cm) – (4.68 x Age in years)

Energy Values:

  • 1 kcal ≈ 4.184 kJ
  • Protein: 4 kcal/g
  • Carbohydrates: 4 kcal/g
  • Fat: 9 kcal/g
  • Alcohol (OH): 7 kcal/g
  • Water, Vitamins, Minerals: 0 kcal/g

Types of Fat Distribution (Obesity)

Android (Apple Shape) Obesity

  • Characterized by fat accumulation in the trunk, upper body, abdomen, chest, shoulder, and neck.
  • Often indicated by a Waist-to-Hip Ratio (WHR) > 0.90 for men or > 0.85 for women.
  • More common in men.
  • Associated Risks: High Blood Pressure (HBP), Type 2 Diabetes Mellitus (DM II), High Cholesterol, Metabolic Syndrome, Coronary Artery Disease.

Gynoid (Pear Shape) Obesity

  • Characterized by fat accumulation in the hips, buttocks, and thighs.
  • Often indicated by a Waist-to-Hip Ratio (WHR) < 0.80 for women or < 0.90 for men.
  • More common in women and may be influenced by genetic background.
  • Generally associated with lower metabolic risk compared to android obesity, but health risks still exist.

Daily Nutritional Needs (General Adult Recommendations)

Note: Needs vary based on age, sex, activity level, and health status. These are general guidelines.

  • Protein (PRT): 10-35% of total energy. Essential amino acids include Tryptophan, Lysine, Methionine. (Example calculation: 88g)
  • Fats: 20-35% of total energy. (Example calculation: 65.3g)
    • Saturated Fat: < 10% of total energy.
    • Polyunsaturated Fatty Acids (PUFA): Includes Omega-3 and Omega-6 fatty acids. Aim for a healthy balance.
    • Trans Fat: < 1% of total energy (minimize intake).
    • Monounsaturated Fatty Acids (MUFA): Make up the remainder of fat intake within the 20-35% range.
  • Carbohydrates (CARBS): 45-65% of total energy. (Example calculation: 352g)
  • Fiber: 25-35 g/day (or more, depending on guidelines).

Dietary Recommendations for Cardiovascular Health (CVS)

  • Saturated Fatty Acids (SFA): < 10% of total energy.
  • Trans Fatty Acids: Minimize intake (< 1% of total energy).
  • Salt (Sodium): < 5g per day (approx. 2000mg sodium), especially important for High Blood Pressure (HBP).
  • Added Sugars: < 10% of total energy (approx. 50g).
  • Fruits: Minimum 200g per day (approx. 2 servings).
  • Vegetables: Minimum 200g per day (approx. 2.5 servings).
  • Fish: 1-2 servings per week (especially oily fish rich in Omega-3).
  • Fiber: 30-45 g per day.
  • Nuts: Approx. 30g per day (unsalted).
  • Alcohol (OH): Limit intake. If consumed, max 1 drink/day for women, max 2 drinks/day for men (1 drink ≈ 10g alcohol).

Understanding Fats:

  • PUFA Sources: Oily fish (salmon, mackerel), walnuts, flaxseeds, sunflower oil.
  • SFA Sources: Animal fats (butter, lard, fatty meat), coconut oil, palm oil.
  • Cholesterol: LDL “ba”) cholesterol contributes to plaque buildup; HDL “goo”) cholesterol helps remove cholesterol from arteries.

Approximate Fat Composition (% SFA / % Unsaturated):

  • Beef Fat: ~35% / ~61%
  • Butter: ~61% / ~33%
  • Chicken Fat: ~29% / ~65%
  • Canola Oil: ~6% / ~92%
  • Coconut Oil: ~90% / ~9%
  • Corn Oil: ~15% / ~84%
  • Olive Oil: ~12% / ~86%
  • Palm Oil: ~48% / ~50%
  • Salmon Fat: ~18% / ~80%

Fiber Types:

  • Soluble Fiber Sources: Oats, barley, beans, lentils, apples, citrus fruits, psyllium.
  • Insoluble Fiber Sources: Whole wheat bread, brown rice, wheat bran, vegetables, nuts, seeds.

Food Safety and Foodborne Illnesses

Types:

  • Infection: Caused by ingesting living pathogenic organisms (e.g., Salmonella, Shigella, Rotavirus, Norovirus, Listeria).
  • Intoxication: Caused by ingesting pre-formed toxins produced by organisms in food (e.g., Staphylococcus aureus enterotoxin, Clostridium botulinum neurotoxin).

Common Examples and Prevention:

  • Salmonella: Often found in poultry, eggs, meat. Prevented by thorough cooking, proper hygiene, avoiding cross-contamination (use separate cutting boards).
  • Shigella: Spread via fecal-oral route, often by contaminated water or food handlers, flies can transmit. Prevented by good hygiene, safe water, hand washing.
  • Rotavirus: Common cause of severe diarrhea in infants/young children. Spread via fecal-oral route. Prevented by hygiene and vaccination (Rota A vaccine).
  • Staphylococcus aureus (Staph): Produces heat-stable enterotoxin. Often spread by food handlers. Food may not look or smell spoiled. Prevented by proper hygiene, temperature control (keep hot foods hot, cold foods cold).
  • Clostridium botulinum (Botulism): Produces potent neurotoxin, often in anaerobic environments. Associated with improperly canned/preserved foods (low-acid vegetables, fish, meats, ham). Prevented by strict hygiene in canning/preserving, boiling home-canned foods, avoiding damaged or bulging cans.

Nutritional Challenges in Developing Countries

  1. Malnutrition (both undernutrition and overnutrition) is a major contributor to disease and early deaths, particularly for mothers and children. Undernutrition contributes to about one-third of all child deaths globally.
  2. Stunting (low height-for-age) is a key indicator of chronic malnutrition, reflecting long-term nutritional deprivation.
  3. Wasting (low weight-for-height) and bilateral pitting edema (Kwashiorkor) are forms of severe acute malnutrition, often resulting from acute food shortages or illness.
  4. Micronutrient deficiencies (lack of essential vitamins and minerals like Vitamin A, Zinc, Iron, and Iodine) are widespread and critical for immunity and healthy development.
  5. Maternal undernutrition contributes to poor fetal development, low birth weight, and higher risks during pregnancy and childbirth.
  6. The World Health Organization (WHO) recommends exclusive breastfeeding for the first six months of life for optimal infant health, growth, and development.
  7. Nutritional problems often persist from childhood into adolescence and adulthood, impacting long-term health and productivity.
  8. Overweight and obesity are increasingly prevalent in developing countries, often coexisting with undernutrition, creating a ‘double burden’ of malnutrition.
  9. Accurate nutrition information systems and surveillance are essential to identify vulnerable populations, target interventions effectively, and monitor progress towards nutritional goals.