BMI

Question 1

What are the 3 distinct body types?

Answer 1

• Ectomorphic
• Mesomorphic
• Endomorphic

Question 2

What are Ectomorphs?

Answer 2

• Ectomorphs have slender frames, low body fat and fast metabolisms. They tend to have muscles that are long and thin, especially in the arms and legs
• Many ectomorphs are too thin and have a desire to increase muscle mass and gain weight. They need to consume plenty of daily calories in the form of complex carbohydrates, lean proteins and healthy fats. They also need to follow a good weightlifting program and avoid doing too much aerobic exercise

Question 3

What are Mesomorphic body types?

Answer 3

• Mesomorphs have lean, muscular bodies with wide shoulders, narrow waists, low body fat and fast metabolisms. They build muscle and lose body fat easily
• Because they’re naturally muscular and low in body fat, mesomorphs often get by with unhealthy diets and infrequent workouts. But even mesomorphs need to eat right and exercise on a regular basis if they want to stay fit and healthy as they age

Question 4

What are Endomorphic body types?

Answer 4

• Endomorphs have stocky frames, high body fat and slow metabolisms. They store body fat easily and have trouble losing it
• High protein, low to moderate carbohydrate diets often work well for endomorphs. Endomorphs need to do plenty of aerobic exercise to burn calories and reduce body fat. They also need to lift weights to get a better muscle to fat ratio and therefore improve metabolism

Question 5

What are features of Anthropometrics?

Answer 5

Measurement

• One-off screening
• Trend observation

Data vs Information / Knowledge

• Reference Values
• Calibration
• Standardisation

Question 6

What are types of measurements?

Answer 6

• Height
• Weight
• BMI
• Skinfold Thickness
• Waist-to-Hip ratio (WHR)
• Mid Upper Arm Circumference (MUAC)
• Ulna length
• Body composition - Bioelectrical impedance

Question 7

What are features of Height Measurements?

Answer 7

• Difficult to measure, accuracy, large variations
• Differences are small: 24 cm increment in the first year of life, 11 cm second year, 8 third
• Low sensitivity and Large measurement errors
• Stunted versus Stunting
  
  • Stunted is a heterogeneous group
  • Stunting is the active process: determinants are acting
• Can be difficult: co-operation of children; ICU etc

Question 8

What are the features of Weight measurements?

Answer 8

• Usually easy to collect
• Sensitive to changes. Changes in two directions up and down
• Standardisation of scales needed - calibration
• Small changes are difficult to measure: food intake of the child, urine, dehydration, temp, etc: not very specific
• Can be difficult: co-operation of children; ICU etc

Question 9

What is BMI?

Answer 9

BMI is a measure of relative obesity.

BMI = Weight in kg / Height in m²

Question 10

What are BMI in Adults?

Answer 10

BMI <18.5 = Under Weight

BMI 18.5-24.9 = Healthy weight range

BMI 25-29.9 = Overweight (grade 1 obesity)

BMI >30-40 = Obese (grade 2 obesity)

BMI >40 = Very obese (‘morbid’ or grade 3 obesity)

Question 11

What are the BMI categories in Children?

Answer 11

• Underweight = Less than the 5th percentile
• Healthy weight = 5th percentile to less than the 85th percentile
• Overweight = 85th to less than the 95th percentile
• Obese = Equal to or greater than the 95th percentile

Question 12

What are Limitations of BMI?

Answer 12

BMI is not accurate when there is significantly increased muscle mass or stunting

BMI varies with age (WHO BMI charts for children)

• The amount of body fat changes with age.
• The amount of body fat differs between girls and boys.
• A Better measure is to plot height and weights on growth charts. (WHO centile charts)

Question 13

What are features of Skinfold Thickness?

Answer 13

• Another measure of body fat.
• Can be measured at a variety of body sites such as Tricep, Bicep, Subscap, Supraspinale, Abdominal, Thigh, Calf
• Ability to predict body fat increases as number of sites measured increases

Question 14

What are features of Waist-to-Hip ratio (WHR)?

Answer 14

We store spare body fat under the skin, and also around the vital organs in our abdomen. Central Abdominal obesity is a predictor of chronic health risk e.g. T2DM and Cardiovascular disease

WHR is a measure of central obesity. There is increased risk when WHR is:

• >1.0 in Men
• >0.85 in Women

Question 15

What are features of the Mid Upper Arm Circumference (MUAC) measurement?

Answer 15

• MUAC is the circumference of the left upper arm, measured at the mid-point between the tip of the shoulder and the tip of the elbow (acromium and olecranon processes)
• MUAC is an appropriate indicator for the assessment of acute adult undernutrition
• The indicator is useful for both screening acute adult undernutrition and for estimating prevalence of undernutrition at a population level
• Suggested MUAC cut-off points for moderate and severe acute adult undernutrition

Moderate = <185mm

Severe = <160mm

Question 16

What is the features of Ulna Length?

Answer 16

• Measure between the point of the elbow (olecranon process) and the midpoint of the prominent bone of the wrist (styloid process) (left side if possible).

Question 17

What are features of Bioelectrical Impedance?

Answer 17

• Bioelectrical impedance analysis (BIA) is a widely used method for estimating body composition. The technology is relatively simple, quick, and noninvasive
• Unknown what it measures specifically in electrical and biological parameters
• Instruments for BIA introduce into the body a known amount of current (I), of about 800 mA, most often at a frequency of 50 kHz
• The current passes between two electrodes, often called the source and sink (or detector), and generates voltages between different points in the body volume according to Ohm’s law
• Conductivity within such materials as blood and urine is high, that of muscle is intermediate, and that of such materials as bone, fat, or air is low. Current will flow predominantly through materials with higher conductivities. There is a lower resistance to current flow in regions where the conductor has a larger cross-sectional area, such as the body trunk, and a higher resistance in regions with a smaller cross-sectional area, such as the forearm
• BIA provides a reliable estimate of total body water under most conditions. It can be a useful technique for body composition analysis in healthy individuals and in those with a number of chronic conditions such as mild-to-moderate obesity, diabetes mellitus, and other medical conditions in which major disturbances of water distribution are not prominent

Question 18

What is Anorexia Nervosa?

Answer 18

• Disorder in which people try to keep their body weight low by dieting, vomiting, taking laxatives or doing excessive amounts of exercise because they are frightened of becoming fat and try hard to become thin.
• Can be very dangerous, and in some people become life threatening. People with anorexia nervosa may see themselves as much bigger than they actually are or underestimate the seriousness of their low weight, so it can be difficult for them to agree that they may need to gain weight
• Anorexia nervosa is most likely to occur during the mid-teenage years

Question 19

What are the Clinical Biochemist role in Nutrition?

Answer 19

• Nutrition Steering Group
• Intestinal Failure Clinics
• Gastroenterology MDT
• Eating Disorders MDT