Nutrition Notes

Nutrition: Pathophysiology of GI System & Body Weight Standards

Basal Metabolic Rate (BMR)

  • BMR is the energy (number of calories) required to fuel involuntary activities.
  • Examples include maintaining body temperature and muscle tone.
  • Men typically have a higher proportion of muscle mass, resulting in a higher BMR.
  • The less active a person is, the greater the proportion of energy used for BMR.
  • Aging, fasting, and sleep can decrease BMR.

Body Mass Index (BMI)

  • BMI is the ratio of weight in kilograms to height in meters squared (m^2).
  • It provides an estimate of body fat.
  • Muscle weighs more than fat.
  • BMI may not be accurate for athletes or those with a muscular build.
  • It may also be inaccurate for people with edema (swelling due to excess fluid), dehydration, or older adults (due to muscle mass loss).

Body Fat Distribution

  • Body fat distribution is an indicator of risk for several diseases:
    • Type 2 diabetes
    • Stroke
    • Hypertension
    • Dyslipidemia (elevated cholesterol and fats in the blood)
    • Cardiovascular disease
  • Waist circumference is a key measurement:
    • Risk increases for men with a waist circumference of 40 inches or more (40+ in).
    • Risk increases for women with a waist circumference of 35 inches or more (35+ in).

BMI and Disease Risk

  • The following table shows disease risk relative to normal weight and waist circumference based on BMI:
    • Underweight: BMI < 18.5
    • Normal: BMI 18.5-24.9
    • Overweight: BMI 25.0-29.9 - Increased risk
    • Obesity (Class I): BMI 30.0-34.9 - High risk
    • Obesity (Class II): BMI 35.0-39.9 - Very High risk
    • Extremely Obese (Class III): BMI 40.0+ - Extremely High risk

Nutrients

Carbohydrates

  • Sugars and starches.
  • Easy to produce and store.
  • Easily and quickly digested (90%).
  • Converted to glucose for transport through the blood or energy for cells.
  • Provide 4 calories/gram.
  • Recommended to be 45-60% of the diet.

Protein

  • Made by combining 22 basic building blocks (amino acids).
  • Required for the formation of genes, enzymes, muscle, bone matrix, skin, and blood.
  • Recommended to be 10-35% of the diet.
  • Provides 4 calories/gram.

Fats

  • Insoluble in water and blood.
  • Majority absorbed in the small intestine, with a small amount excreted.
  • Three types:
    • Trans fats: increase LDL cholesterol (bad) and decrease HDL (good).
    • Saturated fats: More hydrogen, increase serum cholesterol.
    • Unsaturated fats: opposite of saturated fats.
  • Provide 9 calories/gram.
  • Recommended to be less than 10% of the diet.

Regulatory Factors

Vitamins
  • Fat-soluble vitamins: A, D, E, K.
  • Excessive intake of vitamins A & D can be toxic.
  • Fresh foods are preferred over processed foods.
  • Food is preferred over supplements (though some individuals may need supplements).
Minerals
  • Function to provide structure within the body or regulate processes.
  • Excessive soaking/cooking in water can cause loss of minerals.
  • Minerals present in amounts greater than 5g include calcium, phosphates, sulfur, sodium, chloride, potassium, and magnesium.
Water
  • Comprises 50-60% of adult weight.
  • Present within cells.
  • Aids in digestion, absorption, circulation, and excretion.
  • Regulates body temperature.
  • Acts as a lubricant for mucous secretions and movement between joints.

Factors Affecting Nutrition

Age

  • BMR increases.
  • Nutrient demand decreases.
  • Reduced activity leads to decreased calorie needs.
  • Same eating patterns can lead to weight gain.
  • Decreased peristalsis can result in constipation.
  • Loss of dental hygiene can lead to loss of taste.
  • Reduced thirst sensation.

Sex

  • Females typically have a higher proportion of adipose tissue (fat).
  • Males tend to have better metabolism.

Health

  • Surgery, trauma, burns, and crash injuries increase nutrient needs to promote healing.
  • Mental health issues can lead to forgetting or lacking motivation to eat.

Alcohol

  • Alters the body's use of nutrients and storage.
  • Affects the efficiency of absorption.
  • Increases the need for Vitamin B.

Medications

  • Affect absorption.
  • Change the pH balance of the GI tract.
  • Decrease motility (the pace/ease of food movement).
  • Can cause diarrhea.
  • Damage intestinal mucous.

Sociocultural & Religious Factors

  • Location, finances, knowledge, and religion all play a role.
  • Mormon: Avoid coffee, tea, and limit meat intake.
  • Hindu: No meat.
  • Kosher: No pork.