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Lec.2. Theory. Nutrition
Lec.2. Theory. Nutrition
Nutrition is the study of how food nourishes the body.
Nutrients are specific biochemical substances used by the body for growth,
development, activity, reproduction, lactation, health maintenance, and recovery from
illness or injury.
Summary of digestive system anatomy/organ function
Metabolic Requirements
Basal metabolism is the energy required to carry on the involuntary activities of the
body at rest—the energy needed to sustain the metabolic activities of cells and tissues.
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Lec.2. Theory. Nutrition
Metabolic Activities Include:
1. Maintaining body temperature andmuscle tone.
2. Producing and releasing secretions.
3. Propelling food through the gastrointestinal (GI) tract.
4. Inflating the lungs.
5. Contracting the heartmuscle.
 As the amount of energy used on physical activity declines, the proportion of calories
used for basal metabolism increases; it accounts for more than half of most people’s
total energy requirements.
 Because of their larger muscle mass, men have a higher basal metabolic rate (BMR)
than women.
 BMR is about 1 cal/kg of body weight per hour for men and 0.9 cal/kg per hour for
women.
Factors that Increase BMR include:
1. Growth.
2. Infections.
3. Fever.
4. Emotional tension.
5. Extreme environmental temperatures.
6. Elevated levels of certain hormones, especially epinephrine and thyroid hormones.
7. Aging, prolonged fasting, and sleep all decrease BMR.
8. Most nutritionists agree that fasting or following a very–low-calorie diet defeats a
weight loss plan because the body interprets this eating pattern as starvation and
compensates by slowing down the resting metabolic rate, making it even more
difficult to lose weight.
Body Weight Standards
Ideal body weight (IBW) or healthy body weight is an estimate of optimal weight for
optimal health. A general guideline, often called the rule-of- thumb method, determines
ideal weight based on height.
Establish Ideal Body Weight Include Body Mass Index (BMI) Using
Kilograms and Meters:
BMI guidelines:
 BMI below 18.5 is underweight
 BMI between 18.5 and 25 indicates an ideal weight.
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Lec.2. Theory. Nutrition
 BMI of 25 to 29.9 indicates an overweight individual.
 BMI of 30 or greater indicates obesity.
 BMI of 40 or greater indicates extreme obesity.
Calculate The Percent of Weight Change:
Weight loss is considered significant if it falls into the following guidelines:
 1% to 2% in 1 week
 5% in 1 month
 7.5% in 3 months
 10% in 6 months
Waist circumference
 Waist circumference is measured by placing a measuring tape snugly round the
patient’s waist at the level of the umbilicus.
 This measurement is a good indicator of abdominal fat.
 Where excess body fat is deposited is thought to be an important and reliable indicator
of risk for disease, such as type 2 diabetes, dyslipidemia, hypertension, and
cardiovascular disease.
 The risk increases with a waist measurement of over 40 inches in men and 35 inches
in women.
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Lec.2. Theory. Nutrition
Caloric Requirements
 After calorie requirements have been determined, adjustments can be made for weight
gain or loss, as needed.
 For instance, (0.45 kg) of body fat equals about 3,500 cal. Therefore, to gain or lose
(0.45 kg) in a week, daily calorie intake should be increased or decreased,
respectively, by 500 cal (3,500 cal divided by 7 days=500 cal/d).
 Similarly, a weight gain or loss of (0.9 kg) per week would require an adjustment of
1,000 cal/d. Because it becomes increasingly difficult to plan an adequate diet as the
calorie level drops, diets that result in more than a (0.9-kg) weight loss per week are
not recommended.
Energy Nutrients
Carbohydrates, protein, and fats are potential sources of energy for the body
Carbohydrates: commonly known as sugars and starches, are organic compounds
composed of carbon, hydrogen, and oxygen. They serve as the structural framework of
plants. The only animal source of carbohydrate in the diet is lactose, or ―milk sugar.‖
Protein: Protein is a vital component of every living cell. Within the human body,
more than 1,000 different proteins are made by combining various amounts and
proportions.
Fats: Fats in the diet, or lipids, are insoluble in water and, therefore, insoluble in
blood. Ninety-five percent of the lipids in the diet are in the form of triglycerides.
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Lec.2. Theory. Nutrition
Factors Affecting Nutrition
a. Physiologic and Physical
Requirements
Factors
That
Influence
Nutrient
1. Developmental Considerations: Age influences not only nutrient requirements, but
also food intake
2. Gender: Their larger muscle mass translates into higher caloric and protein
requirements (therefore, slightly higher needs for B vitamins that metabolize calories
and protein) because muscle is more metabolically active than adipose tissue.
3. State of Health: The alteration in nutrient requirements that results from illness and
trauma varies with the intensity and duration of the stress. For instance, fevers
increase the need for calories and water.
b. Physical, Sociocultural, and Psychosocial Factors That Influence
Food Choices
1. Economic Factors.
2. Religion.
3. Meaning of Food.
4. Culture.
Nursing Diagnosing
Imbalanced Nutrition as the Problem Data that the nurse collects may lead to the
development of several nursing diagnoses related to nutrition:
1. Imbalanced Nutrition Less Than Body Requirements: related to nothing by mouth
(NPO), inadequate tube feeding, prolonged use of a clear liquid diet, numerous food
intolerance or allergies.
2. Imbalanced Nutrition More Than Body Requirements: related to overeating,
inactivity, metabolic and endocrine disorders, inappropriate use of supplements
Nursing Intervention
1. Providing proper and adequate nourishment to the patient is a team effort
implemented in a variety of settings.
2. Diet orders are written by the physician in the inpatient setting, confirmed by the
dietitian, and frequently explained to the patient by the nurse.
3. The nurse may also be responsible for screening patients at home who are at
nutritional risk.
4. Observing intake and appetite.
5. Evaluating the patient’s tolerance.
6. Assisting the patient with eating.
7. Administering enteral and parenteral feedings.
8. Consulting with the dietitian and physician when dietary problems arise, addressing
the potential for drug–nutrient reactions.
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