Weight, height, energy, protein, and fluid needs

What is Actual Body Weight (ABW)?

Weight measured on a scale at the time of assessment

What is Usual Body Weight (UBW)?

The weight a person typically maintains; it is useful for assessing weight change and identifying unintentional weight loss or gain

Usually within the last year or longer

What is Ideal Body Weight (IBW)?

A calculated estimate of weight based on height, used for clinical comparisons such as %IBW (Hamwi formula)

What is Adjusted Body Weight (AdjBW)?

A calculated weight historically used in obesity, amputations, and fluid overload; the slides note it is rarely used today

What is frame-size adjusted weight?

Adjustment of IBW based on small, medium, or large frame size using wrist circumference or elbow breadth

How is IBW adjusted for frame size?

Approximately ±10% of IBW

What is dry weight?

Weight without excess fluid; commonly used in dialysis and Congestive Heart Failure (CHF) to better estimate true nutritional status

What is admission weight used for?

As a baseline for inpatient monitoring and comparison with discharge weight

What is a stated weight?

Weight reported by the patient when a scale measurement is unavailable; it is less reliable than measured weight

What is estimated weight?

A clinician-estimated weight used when the patient cannot stand, based on methods such as a bed scale, Nutrition Focused Physical Exam (NFPE), or visual estimation

Why is percent weight change clinically important?

It helps identify clinically significant weight loss and is used in malnutrition diagnosis

What should be done before obtaining a standing weight?

Zero the scale, remove heavy clothing/shoes/items in pockets, account for wheelchairs or prosthetics, and consider recent urination/BM

What safety consideration is important during standing weights?

Fall prevention, including use of a gait belt when appropriate

Which IBW formula is described as the preferred method in the slides?

The peterson formula

What do ASPEN and ESPEN say about adjusted body weight?

ASPEN no longer recommends its use; ESPEN recommends/allows it in some individuals with obesity

What does BMI assess?

Weight status using accurate measurements of height and weight

What height methods can be used for non-ambulatory patients?

Knee height: Requires a special device

Arm-to-arm span: Equation based fingertip to fingertip (prone to over estimate)

Demi-span: Equation based, sternal notch to middle finger

Segmental measurements: Equation based, using length of tibia, ulna or knee height

What is energy balance?

Energy balance = energy intake − energy output

What nutrients provide energy to the body?

Carbohydrates, fats, proteins, and alcohol

What is energy?

Energy is extracted from food through controlled electron transfer reactions with oxygen to create energy as ATP

What is Basal Metabolic Rate (BMR)?

The calories required to maintain basic body functions at complete rest, after fasting, under tightly controlled conditions

What is Resting Energy Expenditure (REE)?

Energy used at rest to maintain essential functions such as breathing, heart function, brain function, and body temperature

What percentage of daily energy expenditure is REE?

Roughly 60–75% for most people

What term is used interchangeably with REE?

Resting Metabolic Rate (RMR)

What is the major difference between BMR and REE?

BMR is measured under stricter conditions; REE is measured under more practical resting conditions and is usually slightly higher

BMR measures the absolute minimum energy required for vital functions under strict, fasted laboratory conditions, whereas REE measures energy expenditure while resting under less restrictive, real-world conditions

What is Total Energy Expenditure (TEE)?

The total amount of energy expended to sustain life, activity, and growth

What are the major components of TEE?

REE, thermic effect of food (TEF), activity energy expenditure (AEE), and growth-related energy expenditure when applicable

Approximately what percentage of TEE is the Resting Energy Expenditure, Thermic Effect of Food, Energy Expenditure, and Growth Related Energy Expenditure?

REE: 60-70%

TEF: 10%
AEE: 30-40%

GREE: 1-2% after age 2, 0% mid 20s

What is Estimated Energy Requirement (EER)?

The average daily energy intake predicted to maintain energy balance in a healthy individual

What is Estimated Energy Requirement (EER)?

The average daily energy intake predicted to maintain energy balance in a healthy individual

What factors are incorporated into EER?

REE/basal metabolism, physical activity, TEF, and energy for growth, pregnancy, or lactation when applicable

What is the key difference between TEE and EER?

TEE = energy output/burned in a day

EER = recommended energy input/intake needed to maintain energy balance

EER values apply primarily to what population?

Healthy individuals with a healthy weight

What two factors have the greatest effect on REE?

Body size and body composition

How does lean body mass affect REE?

Greater lean body mass is associated with higher energy expenditure

How does hyperthyroidism/hypothyroidism affect energy expenditure?

Hyperthyroidism: It increases energy expenditure

Hypothyroidism: It decreases energy expenditure

How does fever affect REE?

REE increases approximately 7% for every 1°F above 98.6°F

Is TEE or REE affected by illicit substances?

TEE

What is considered the gold standard for measuring REE in the clinical setting?

Indirect calorimetry/metabolic cart (the device used)

Expensive

What method is considered a gold standard for measuring TEE in research?

Doubly labeled water

What is the Doubly Labelled Water Method?

The technique is a unique chemical variation of indirect calorimetry. It works by tracking how your body naturally eliminates two safe, non-radioactive "heavy" water isotopes over a period of 7 to 14 days

The participant drinks a small, precisely measured cup of water enriched with two stable isotopes, which will slowly leave the participant’s body

The difference between the two elimination rates tells researchers exactly how much carbon dioxide the body produced over those weeks

What does indirect calorimetry measure?

Oxygen consumption (VO₂) and carbon dioxide production (VCO₂)

What does indirect calorimetry calculate?

REE/RMR and the primary fuel substrate being used through the respiratory quotient

What RQ represents primarily carbohydrate metabolism, mixed diet, protein metabolism, and fat metabolism?

Carbohydrate metabolism: 1.0

Mixed diet: 0.85

Protein metabolism: 0.82

Fat metabolism: 0.70

What does the Mifflin-St Jeor equation estimate?

RMR/REE; an activity factor is then used to obtain TEE

Which predictive equation did the slides identify as the most reliable in non-obese and obese individuals?

Mifflin-St Jeor

What weight should be used to calculate calorie/protein needs if BMI <30?

Actual Body Weight

What weight should be used for patients with obesity (BMI ≥30)?

IBW or AdjBW; the slides note ASPEN prefers IBW while ESPEN allows AdjBW

What weight should be used for an underweight or malnourished patient?

Actual Body Weight

What weight should be used for severe edema, ascites, or fluid overload?

Dry weight or pre-illness weight

What does a 24-hour UUN study measure?

The amount of urea nitrogen excreted in urine during a 24-hour period

Why is UUN useful?

To assess nitrogen balance, estimate protein needs, evaluate protein metabolism, and assess adequacy of protein intake

What must be recorded during a 24-hour UUN study?

Strict 24-hour urine collection and all sources of protein intake, including PO (by mouth) intake, tube feeding, or TPN

What does positive nitrogen balance mean?

Nitrogen intake is greater than nitrogen losses

What does negative nitrogen balance mean?

Nitrogen loss exceeds intake, indicating insufficient protein

What is the nitrogen balance goal for a critically ill patient?

Positive nitrogen balance to support healing

What is a false low?

Occurs when the lab report shows a lower amount of nitrogen than what is actually in the patient’s body

It makes it look like the patient is retaining protein and healing, when they may actually be losing muscle

Could occur due to poor urine collection, acute/chronic renal failure, hemodialysis, open wounds, diarrhea

What is a false high?

Occurs when the lab report shows an artificially elevated amount of nitrogen in the urine compared to what is truly happening with the patient's baseline metabolism

It mistakenly signals that the body is severely wasting and breaking down its own muscle (a false negative nitrogen balance), which might lead a medical team to overfeed a patient unnecessarily

Could occur due to medications that increase protein breakdown, steroids, glucagon

What does NPC:N stand for?

Non-Protein Calorie-to-Nitrogen Ratio

What are non-protein calories?

Calories from carbohydrate and fat

What does the NPC:N ratio evaluate?

Whether the patient is receiving enough protein relative to calories from carbohydrate and fat, helping preserve muscle and allow protein to be used for tissue repair