Biochemistry Lecture 10 Flashcards
Nutritional assessment
determine the quantity of current nutrient stores in the body (lipids, proteins, vitamins, and minerals)
Application of nutritional assessment?
health promotion, disease prevention and treatment
Measures of nutritional status
ABCD
Anthropometric measurements
Biochemical markers
Clinical evaluation
Dietary history
Anthropometric measurement definition
measurements that characterized an individual’s body shape and size
Weight & Height
- BMI
- Percentiles - children
Fat distribution
- Weight circumference
- Waist to hip ratio
Percent body fat
skinfold thickness
Body protein
- Mid-upper-arm circumference (MUAC)
- Calf circumference (CC)
Body composition
- Dual energy x-ray absorptiometry (DEXA)
- Bioelectric impedance analysis (BIA)
BMI is a ratio of
weight to height
Advantage of BMI
Streamlined to one number that is used to evaluate body weight (does not matter if male or female, short or tall)
Limitations of BMI
- Sex differences (for a given BMI< women have a decreased risk of premature mortality relative to men). Women have about 10% more body fat than men that is not associated with increased risk of mortality
- Fat distribution
Mortality risk that are associated with increased BMI
Risk of diseases such as type 2 diabetes, hypertension, heart disease, and stroke are positively correlated with BMI.
BMI does not account for
- stages of development: BMI should not be used for children and pregnant women
- Body composition (muscle vs fat) - this can be misleading for muscular people, frail elderly may be unhealthy even though they have a “healthy BMI”. With aging, muscle mass decreases while body fat increases. The BMI will remain the same as long as there is no change in body weight.
BMI used for adults, not
children
Clinic commonly uses what for infants and children length and weight?
percentiles
Percentile
A number where a certain percentage of scores fall below that number. In this case, percentiles are in reference to observations in a population.
Fat distribution is more important than?
the amount of fat when it comes to determining the disease risk associated with obesity
Upper body obesity (apple-shaped) is associated with?
a greater risk for heart disease, hypertension, and diabetes
Lower body obesity (pear-shaped people)
contributes little to disease risk
Fat distribution is
sex dependent
In non-obese men, fat is?
evenly distributed - while in overweight or obese men, testosterone favors deposition of excess fat in the abdomen
In non obese women, more fat is in the
gluteofemoral area (estrogen dependent and not associated with an increased risk of disease
Waist circumference (WC) measures
abdominal fat, just above the hip bone
Waist to hip ratio (WHR) is the
waist circumference divided by hip circumference (can be misleading)
Obesity can be defined on basis of
Percentage of body weight, which varies with age and sex. Increased diseased risk.
About 50% to 80% of adipose tissue is?
subcutaneous, so skinfold thickness can be used to estimate % body fat
The folded skin is measured with?
calipers
Skinfold thickness pros and cons
pro: technique is easy, rapid, and inexpensive
cons: results can vary depending on the skill and experience of the technician. Usually require estimates at multiple sites to increase accuracy.
Body protein is divided into two compartments
- somatic protein (skeletal muscle)
- visceral protein (serum levels of albumin)
MUAC is used to assess
muscle wasting or malnutrition in children
(6-59 months)
Calf circumference can be used as a marker of
malnutrition/sarcopenia
DEXA
-Most common in a clinic sitting
-Dual energy x ray absorptiometry
-Estimate fat free mass, body fat, and bone mineral density by using differential attenuation of photon beams of two levels of intensity
DEXA pro and cone
pro: accurate and reproducible
con: expensive and cumbersome
Body composition: BIA
bioelectric impedance analysis, uses an electrical current to estimate fat and fat free mass
Water is the most conductive for the current; body fat has very
little water compared to lean tissues
pro: easy and inexpensive
con: hydration status can skew rsults
Know BMI calculations
BIA commercial products
smart scales, now smart watches!
same errors can arise with hydration, in addition to user errors
Measurements are not precise and should not be used for diagnostic purposes, but could be a helpful tool for monitoring changes in body composition over time
Red cell indices can show deficiency in
vitamin B12 and iron
Low levels of albumin or prealbumin could indicate
malnutrition or infection
Serum lipids
cholesterol and triglycerides
Malabsorption
fecal fat can be used to determine if the ability to absorb fat is impaired
Clinical Assessment
- % Weight Loss
- Can the weight loss be explained?
- Impact on muscle compartment
- Stress increases RMR and caloric needs
- Fat and protein stores, wound healing
- Overall verdict
Weight change is one of the most significant measures of
nutritional status
Individual serves as his/her own
reference
Any change in weight is reported as
percentage of one’s “original” or “unusual” weight
serial weight measurement is most useful to
track body weight because there are multiple recorded data points (weekly, monthly, yearly)
Most common procedures used to determine dietary history
are:
- 24 hour recall
- food frequency questionnaires
- 1 to 3 day recored
