Body composition and Practical
Nutritional Assessment
Khursheed Jeejeebhoy
Determinants of Nutritional Status

Nutritional health
• a state of equilibrium
• nutrient intake and requirements balance.

Malnutrition
• net nutrient intakes < requirements.
• change in body and blood composition
• changes in body and blood composition have
traditionally used to assess nutritional status.
Nutritional Assessment: Veterinary approach
C --
C– P--
Objective of Nutritional Assessment

Veterinary Objective:
• Mass of muscle, fat and viscera in the carcass.

Clinical Objective:
• To improve patient outcome.

Can measurement of muscle, fat and viscera
predict outcome?
Levels of Body Components
Tissue-Organs
Adipose tissue
Skeletal Muscle
Cellular Molecular Atomic
Adipocyte
Lipid
Hydrogen
Water
Cells
Carbon
Visceral Organs
Skeleton
Oxygen
ECF
Protein
ECS
Mineral
N, Ca,P,K,Na,Cl
Nutritional Assessment: Tissue-Organs
1. Body Weight and Weight Loss
1. BMI = Wt/Ht2 < 15 is associated with mortality
2. Unintentional weight loss is associated with mortality
3. Weight is difficult to assess due to:
1. Dehydration
2. Edema
3. Dialysate
4. Weight loss estimate has errors of recall
Nutritional Assessment: Tissue-Organs
1. How much muscle and fat: Anthropometry
Arm muscle circumference
Skin Fold thickness
2. How much circulating protein: Visceral Protein
Albumin
Prealbumin
Transferrin
3. Errors of Antropometry
Errors due to Baseline values
Variability of measurement
What is abnormal?
Errors due to edema
4. Errors of Visceral Protein
Altered by hydration status
Altered by Protein loss (GI and renal)
Altered by Infection
Nutritional Assessment: Tissue-Organs
DUAL-ENERGY XRAY ABSORPTIOMETRY (DEXA)

Two low level energy xrays to differentiate
tissues of different densities.
 The only method for assessing the skeleton.
 Differentiates body composition into:
• Fat
• Muscle
• Bone

No data to predict outcome
Levels of Body Components
Tissue-Organs
Cellular
Molecular
Atomic
Adipose tissue
Adipocyte
Lipid
Hydrogen
Water
Skeletal Muscle
Cells
Carbon
Visceral Organs
Skeleton
Oxygen
ECF
Protein
ECS
Mineral
N, Ca,P,K,Na,Cl
Nutritional Assessment: Cellular




Cell mass = Total body potassium / 150 X
1/80
Potassium content of cells = 150 mmol/L
Solid to fluid in cells = 1:4
Intracellular potassium is very sensitive to
malnutrition and refeeding
Nutritional Assessment: Cellular
Am J Clin Nutr 1982;35(suppl) 1117-1127






Patients with anorexia Nervosa
Weeks of feeding
TBN TBK K/TBN
kg mM
0
1.2 1590 1.31
4
1.33 1897 1.42
8
1.37 2103 1.53
Levels of Body Components
Tissue-Organs
Adipose tissue
Skeletal Muscle
Cellular Molecular Atomic
Adipocyte
Lipid
Hydrogen
Water
Cells
Carbon
Visceral Organs
Skeleton
Oxygen
ECF
Protein
ECS
Mineral
N, Ca,P,K,Na,Cl
Nutritional Assessment: Molecular




Body Weight = Fat mass (FM) + Fat Free
Mass (FFM)
Hydration of FFM = 73%
FFM= Total Body Water/0.73
Total Body Water can be assessed by:
• Isotope dilution
• Bioelectric Impedance
Nutritional Assessment: Molecular
1. Isotope dilution
1. Total body water
2. Extracellular water
3. No correlation with outcome
2. Bioimpedance Analysis
1. Easy to perform
2. Measures body water
3. No correlation with outcome
3. DEXA
1. Measures FM
2. Muscle mass from which FFM can be derived
3. Bone mass
Levels of Body Components
Tissue-Organs
Adipose tissue
Skeletal Muscle
Cellular Molecular Atomic
Adipocyte
Lipid
Hydrogen
Water
Cells
Carbon
Visceral Organs
Skeleton
Oxygen
ECF
Protein
ECS
Mineral
N and Ca
Nutritional Assessment: Atomic





Measured By:
Hydrogen Neutron Activation
Carbon Inelastic Neutron scattering
Nitrogen Prompt Gamma Emission
Calcium Neutron Activation
NUTRIENT
INTAKE
(-)
(+)
METABOLIC
STRESS
NUTRITIONAL
STATE
INITIAL
CRITICAL STATE
(+)
GASTROINTESTINAL
DISEASE
NUTRITIONAL ASSESSMENT
WEAKNESSES IN CURRENT CONCEPT
SNAPSHOT IN TIME
DOES NOT PREDICT FUTURE
OUTCOME DEPENDS UPON FUTURE
COURSE
Subjective Global Assessment
TABLE 1. FEATURES OF SUBJECTlVE GLOBAL ASSESSMENT
A. History
1. Weight change and height :
Current Height ________ cm, Weight _______ kg.
Overall loss in past 6 months: ______ kg
_______ %
Change in past 2 weeks (use + or -): _______ kg , ________ %
2. Dietary intake change (relative to usual intake)
No change.
Change
duration =
days.
Type: Suboptimal solid diet.
Hypocaloric liquids.
Starvation
Supplement: (circle) nil, vitamin, minerals.
3. Gastrointestinal symptoms that persisted for >2 weeks.
None
Nausea
Vomiting
Diarrhea
Pain At rest
on eating
4. Functional capacity
No dysfunction .
Disfunction: duration
days
type: Working suboptimally
Ambulatory but not working
Bedridden.
Predictive value of a test
Predictive ability of SGA
Nutritional Prognosis in Hospital Patients
Perman et al. Am J Clin Nutr 2002;75:426S



448 Hospital Patients
SGA assessment and record of other risk
factors influencing prognosis
Logistic regression to evaluate independent
risk of malnutriton by SGA on
complications and mortality
Nutritional Prognosis in Hospital Patients
Perman et al. Am J Clin Nutr 2002;75:426S
Odds Ratio
* only odds ratio of BC not different from A
9
8
7
6
5
4
3
2
1
0
*
Death
Sepsis
Pneumonia
SGA A
SGA B
Pres. Sores
SGA C
Wound
dehiscence
NUTRITIONAL ASSESSMENT
CLINICALLY USEFUL CONCEPTS
SHOULD DISTINGUISH BETWEEN
DISEASE AND LACK OF NUTRITION
SHOULD PREDICT OUTCOME
(MORBIDITY AND MORTALITY)
SHOULD IDENTIFY PATIENTS IN WHOM
NUTRITIONAL SUPPORT WILL ALTER
OUTCOME
Mohandas IJG 2005;24:246-250
Subjective Global Assessment and Cancer

Thoresen et al. Palliat Med. 2002 ;16:33-42.
• Sensitivity 96% and specificity 83%

Persson et al. Clin Nutr 1999; 18:71-77
• Survival Lower in SGA B+C vs A (P<0.001)