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Textbook
1. Medical assistant
2. Electronic records
3. Medical terminology and anatomy
4. The fundamentals of infection control
5. Introduction to vital signs
6. The patient interview and history
7. The physical examination
8. Appointment scheduling
9. Insurance billing
10. Diagnostic coding and the ICD-10-CM System
11. Procedural coding
12. Medical billing and reimbursement essentials
13. Assisting with medical specialties
14. Assisting with the musculoskeletal system
15. Assisting with the cardiovascular system
16. Assisting with the respiratory system
17. Assisting with the nervous system
18. Anatomy and physiology of the urinary system
19. Assisting in obstetrics and gynecology
20. Assisting in endocrinology
21. Assisting in ophthalmology & otolaryngology
22. Assisting in gastroenterology
23. Assisting in the immune & lymphatic systems
24. Assisting in pediatrics: the developmental stages and care
25. The medical assistant’s role in caring for the older patient
26. The role of the medical assistant in physical therapy examination and assessment
27. Preparing for minor surgery: room, solutions, and supplies
28. Introduction to the clinical laboratory
29. Urinalysis
30. Blood collection
31. Analysis of blood
32. Electrocardiography and heart structure
33. The principles of pharmacology
34. Essential calculations and measurement systems
35. Solid, liquid, & solutions medication doses
36. Administering medications
37. Metabolism and core nutrient roles
37.1 Health, nutrition, and metabolism
37.2 Fats, minerals, and water
37.3 Dietary guidance and food labels
37.4 Diets for chronic conditions
37.5 Diets for consistency and weight management
37.6 Diets for special needs and life stages
38. Medical emergencies in the healthcare setting
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37.1 Health, nutrition, and metabolism
Achievable CCMA
37. Metabolism and core nutrient roles
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Health, nutrition, and metabolism

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Health & nutrition

Nutrition is a field of study that examines the substances in food that help us grow and stay healthy. Nutrition can also be defined as the intake of food for the body’s dietary needs. It is important to eat a healthy and balanced diet. Nutrients are the chemicals in food that the body uses for energy, growth, and development. Nutrients include water, protein, carbohydrate, fat, vitamins, and minerals.

A medical assistant helps the provider by coaching patients on dietary changes. It is important to be aware of nutrients and the different types of diets commonly ordered in the ambulatory care environment. This chapter discusses metabolism and the nutrients essential for growth and development. Dietary requirements, along with medically ordered diets, are also discussed.

Metabolism

Metabolism is the process the body uses to obtain or make energy from the food eaten. The following sections discuss the phases of metabolism and the variables that affect metabolism.

Phases of metabolism

Metabolism has two phases:

  • Catabolism: The process of breaking down molecules into smaller molecules, resulting in energy being released
  • Anabolism: The process of smaller molecules being used to build larger molecules with the use of energy

For example, you eat a piece of chocolate candy with peanuts. It is broken down by enzymes in the intestines. The enzymes break down the proteins into amino acids, the fats into fatty acids, and the complex carbohydrates into simple sugars (e.g., glucose). These substances are absorbed by the blood and brought to the cells. In the cells, other enzymes catabolize, or break down, these substances, and energy is released. The energy released can be used or stored by the body. The small molecules created from catabolism are used to create larger molecules as the body repairs tissues and performs other functions. This process requires energy and is called anabolism. Every action of the body, involuntary or voluntary, requires energy.

Many times, metabolism is thought of as what influences our bodies to gain or lose weight. This is where calories come in. A calorie is a unit that measures how much energy is in a particular food. People use calories or energy at different rates. Some people eat a lot of food and do not put on any weight, whereas others feel they look at food and gain weight. The number of calories a person burns each day is affected by the following factors:

  • How much the person exercises
  • The amount of fat and muscle on the person’s body
  • The person’s basal metabolic rate (BMR), or the rate the body burns calories while the person is at rest

Basal metabolic rate

The BMR can play a role in a person’s tendency to gain weight. For example, two people eat and exercise the same amount, but they have two different BMRs. The person with the lower BMR would have a greater tendency to gain more weight. Remember, the body stores unused calories as fat.

A number of variables will affect the BMR:

  • Genetics: Some people are born with a higher metabolism.
  • Sex: Males have a higher density of lean muscle mass with a lower body fat percentage. This causes a higher BMR.
  • Age: BMR decreases with age.
  • Weight: The heavier an individual, the higher the BMR.
  • Body surface area: This relates to a person’s height and weight. The larger the body surface area, the higher the BMR.
  • Body fat percentage: The lower a person’s body fat percentage, the higher the BMR.
  • Diet: Starvation and low-calorie diets can reduce the BMR.
  • Body temperature: A higher body temperature results in an increased BMR.
  • External temperature: The colder the external temperature, the more the body has to provide additional heat to maintain the body’s temperature. This increases the BMR.
  • Thyroxin: Produced by the thyroid gland, thyroxin can increase the BMR.
  • Exercise and lean muscle tissue: Exercise will create lean muscle tissue, which increases the BMR.
  • Drugs: Certain drugs (e.g., caffeine) can increase the BMR.

Health & nutrition

  • Nutrition: study of food substances for growth and health
  • Nutrients: water, protein, carbohydrate, fat, vitamins, minerals
  • Importance of balanced diet and dietary coaching in healthcare

Metabolism

  • Metabolism: body’s process to obtain/make energy from food
  • Two phases:
    • Catabolism: breaking down molecules, releases energy
    • Anabolism: building larger molecules, uses energy
  • Calorie: unit of food energy; affected by exercise, body composition, BMR

Basal metabolic rate (BMR)

  • BMR: calories burned at rest; influences weight gain/loss
  • Factors affecting BMR:
    • Genetics, sex (higher in males), age (decreases with age)
    • Weight, body surface area, body fat percentage
    • Diet (starvation lowers BMR), body/external temperature
    • Thyroxin (thyroid hormone), exercise, certain drugs (e.g., caffeine)

Important nutrients for the body

  • Essential nutrients: must be obtained from food
  • Nonessential nutrients: made by the body
  • Nutrient-rich foods: high in nutrients, low in calories
  • Non–nutrient-rich foods: “empty calories,” low in nutrients

Carbohydrates

  • 45–65% of daily calories; main energy source
  • Includes simple sugars, starches, fiber

Simple sugars

  • Found in fruits, vegetables (fructose, glucose), milk (lactose)
  • Non–nutrient-rich sources: desserts, candy, soda, syrups, white sugar
  • Rapidly absorbed; quick energy; raise blood glucose quickly

Starches

  • Complex carbohydrates; digested to simple sugars
  • Nutrient-rich: legumes, starchy vegetables, whole grains
  • Non–nutrient-rich: white bread, white rice, crackers
  • Excess carbs can be converted to fat
  • Smart choices: whole grains, fruits, vegetables, legumes, low-fat dairy

Whole grains and refined grains

  • Whole grains: contain bran, germ, endosperm (e.g., whole wheat, oatmeal)
  • Refined grains: bran/germ removed; lower in fiber, B vitamins, iron
    • Often enriched with B vitamins and iron, but not fiber

Glycemic index (GI)

  • Numeric index (0–100) of how much a carb food raises blood glucose
  • High-GI (≥70): rapid increase; Low-GI (≤55): smaller increase
  • Low-GI foods recommended to reduce risk of type 2 diabetes, heart disease

Fiber

  • Not digested; does not raise blood glucose
  • Promotes fullness, weight management, regularity
  • Two types:
    • Soluble fiber: dissolves in water, lowers blood glucose/cholesterol (e.g., legumes, oats, fruits)
    • Insoluble fiber: bulks stool, prevents constipation (e.g., whole grains, vegetables, nuts)
  • Fiber supplements: Metamucil (psyllium), Citrucel (methylcellulose), Fibercon (calcium polycarbophil)
    • Drink plenty of water with supplements

Protein

  • 10–35% of daily calories; broken down to amino acids
  • Functions: energy (if carbs absent), tissue growth/repair, enzymes, hormones, antibodies
  • Protein malnutrition: growth failure, muscle loss, anemia, edema, immune deficiency

Amino acids

  • Essential: must come from food
  • Nonessential: made by body
  • Conditional: needed during illness/stress
  • Complete proteins: contain all essential amino acids (e.g., meat, dairy, eggs, quinoa)
  • Incomplete proteins: lack some essential amino acids (e.g., nuts, legumes, grains, vegetables)
  • Smart choices: lean meats, seafood with omega-3, limit processed meats, choose unsalted nuts/seeds

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Next  | 37.2 Fats, minerals, and water
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Health, nutrition, and metabolism

Health & nutrition

Nutrition is a field of study that examines the substances in food that help us grow and stay healthy. Nutrition can also be defined as the intake of food for the body’s dietary needs. It is important to eat a healthy and balanced diet. Nutrients are the chemicals in food that the body uses for energy, growth, and development. Nutrients include water, protein, carbohydrate, fat, vitamins, and minerals.

A medical assistant helps the provider by coaching patients on dietary changes. It is important to be aware of nutrients and the different types of diets commonly ordered in the ambulatory care environment. This chapter discusses metabolism and the nutrients essential for growth and development. Dietary requirements, along with medically ordered diets, are also discussed.

Metabolism

Metabolism is the process the body uses to obtain or make energy from the food eaten. The following sections discuss the phases of metabolism and the variables that affect metabolism.

Phases of metabolism

Metabolism has two phases:

  • Catabolism: The process of breaking down molecules into smaller molecules, resulting in energy being released
  • Anabolism: The process of smaller molecules being used to build larger molecules with the use of energy

For example, you eat a piece of chocolate candy with peanuts. It is broken down by enzymes in the intestines. The enzymes break down the proteins into amino acids, the fats into fatty acids, and the complex carbohydrates into simple sugars (e.g., glucose). These substances are absorbed by the blood and brought to the cells. In the cells, other enzymes catabolize, or break down, these substances, and energy is released. The energy released can be used or stored by the body. The small molecules created from catabolism are used to create larger molecules as the body repairs tissues and performs other functions. This process requires energy and is called anabolism. Every action of the body, involuntary or voluntary, requires energy.

Many times, metabolism is thought of as what influences our bodies to gain or lose weight. This is where calories come in. A calorie is a unit that measures how much energy is in a particular food. People use calories or energy at different rates. Some people eat a lot of food and do not put on any weight, whereas others feel they look at food and gain weight. The number of calories a person burns each day is affected by the following factors:

  • How much the person exercises
  • The amount of fat and muscle on the person’s body
  • The person’s basal metabolic rate (BMR), or the rate the body burns calories while the person is at rest

Basal metabolic rate

The BMR can play a role in a person’s tendency to gain weight. For example, two people eat and exercise the same amount, but they have two different BMRs. The person with the lower BMR would have a greater tendency to gain more weight. Remember, the body stores unused calories as fat.

A number of variables will affect the BMR:

  • Genetics: Some people are born with a higher metabolism.
  • Sex: Males have a higher density of lean muscle mass with a lower body fat percentage. This causes a higher BMR.
  • Age: BMR decreases with age.
  • Weight: The heavier an individual, the higher the BMR.
  • Body surface area: This relates to a person’s height and weight. The larger the body surface area, the higher the BMR.
  • Body fat percentage: The lower a person’s body fat percentage, the higher the BMR.
  • Diet: Starvation and low-calorie diets can reduce the BMR.
  • Body temperature: A higher body temperature results in an increased BMR.
  • External temperature: The colder the external temperature, the more the body has to provide additional heat to maintain the body’s temperature. This increases the BMR.
  • Thyroxin: Produced by the thyroid gland, thyroxin can increase the BMR.
  • Exercise and lean muscle tissue: Exercise will create lean muscle tissue, which increases the BMR.
  • Drugs: Certain drugs (e.g., caffeine) can increase the BMR.
Key points

Health & nutrition

  • Nutrition: study of food substances for growth and health
  • Nutrients: water, protein, carbohydrate, fat, vitamins, minerals
  • Importance of balanced diet and dietary coaching in healthcare

Metabolism

  • Metabolism: body’s process to obtain/make energy from food
  • Two phases:
    • Catabolism: breaking down molecules, releases energy
    • Anabolism: building larger molecules, uses energy
  • Calorie: unit of food energy; affected by exercise, body composition, BMR

Basal metabolic rate (BMR)

  • BMR: calories burned at rest; influences weight gain/loss
  • Factors affecting BMR:
    • Genetics, sex (higher in males), age (decreases with age)
    • Weight, body surface area, body fat percentage
    • Diet (starvation lowers BMR), body/external temperature
    • Thyroxin (thyroid hormone), exercise, certain drugs (e.g., caffeine)

Important nutrients for the body

  • Essential nutrients: must be obtained from food
  • Nonessential nutrients: made by the body
  • Nutrient-rich foods: high in nutrients, low in calories
  • Non–nutrient-rich foods: “empty calories,” low in nutrients

Carbohydrates

  • 45–65% of daily calories; main energy source
  • Includes simple sugars, starches, fiber

Simple sugars

  • Found in fruits, vegetables (fructose, glucose), milk (lactose)
  • Non–nutrient-rich sources: desserts, candy, soda, syrups, white sugar
  • Rapidly absorbed; quick energy; raise blood glucose quickly

Starches

  • Complex carbohydrates; digested to simple sugars
  • Nutrient-rich: legumes, starchy vegetables, whole grains
  • Non–nutrient-rich: white bread, white rice, crackers
  • Excess carbs can be converted to fat
  • Smart choices: whole grains, fruits, vegetables, legumes, low-fat dairy

Whole grains and refined grains

  • Whole grains: contain bran, germ, endosperm (e.g., whole wheat, oatmeal)
  • Refined grains: bran/germ removed; lower in fiber, B vitamins, iron
    • Often enriched with B vitamins and iron, but not fiber

Glycemic index (GI)

  • Numeric index (0–100) of how much a carb food raises blood glucose
  • High-GI (≥70): rapid increase; Low-GI (≤55): smaller increase
  • Low-GI foods recommended to reduce risk of type 2 diabetes, heart disease

Fiber

  • Not digested; does not raise blood glucose
  • Promotes fullness, weight management, regularity
  • Two types:
    • Soluble fiber: dissolves in water, lowers blood glucose/cholesterol (e.g., legumes, oats, fruits)
    • Insoluble fiber: bulks stool, prevents constipation (e.g., whole grains, vegetables, nuts)
  • Fiber supplements: Metamucil (psyllium), Citrucel (methylcellulose), Fibercon (calcium polycarbophil)
    • Drink plenty of water with supplements

Protein

  • 10–35% of daily calories; broken down to amino acids
  • Functions: energy (if carbs absent), tissue growth/repair, enzymes, hormones, antibodies
  • Protein malnutrition: growth failure, muscle loss, anemia, edema, immune deficiency

Amino acids

  • Essential: must come from food
  • Nonessential: made by body
  • Conditional: needed during illness/stress
  • Complete proteins: contain all essential amino acids (e.g., meat, dairy, eggs, quinoa)
  • Incomplete proteins: lack some essential amino acids (e.g., nuts, legumes, grains, vegetables)
  • Smart choices: lean meats, seafood with omega-3, limit processed meats, choose unsalted nuts/seeds

More from Metabolism and core nutrient roles

  • Fats, minerals, and water
  • Dietary guidance and food labels
  • Diets for chronic conditions
  • Diets for consistency and weight management
  • Diets for special needs and life stages