BIOL 380 Lecture Notes - Lecture 10: Neuropeptide Y, Indirect Calorimetry, Impaired Glucose Tolerance
19 Jun 2018
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BIOL 380 – Lecture 10 (done before lecture 9) – Energy Balance and Body Weight
What is a healthy weight?
- Appropriate for your age and physical development
- You can achieve and sustain without constantly dieting
- Based on genetic background
- Compatible with normal BP, lipid level, glucose tolerance
- Promote good habit and allow to participate in regular physical activity
- Acceptable to you
-Underweight: having too little body fat to maintain health
-Overweight: moderate amount of excess body fat
-Obesity: excess amount of body fat that adversely affect health
-Morbid obesity: body weight exceeds 100% of normal, high risk of serious health problems
How to evaluate body weight?
1) BMI index or Quetelet’s index: Ratio of body weight square of height
OR height
- Conversion factors
o1 kg = 2.2 lb
o(m) = 0.0254 x inches
BMI category and risks of health problems
- Type 2 diabetes, high BP, heart disease – BMI over 30
Limitations of BMI
- BMI neither tells how much body mass composed of fat nor where is excess fat on body
- Not a fair indication for people above 65
- Cannot reflect muscle and bone growth in children
- BMI more strongly associated with height in young people.
- Does not take into account physical and metabolic differences for people from different ethnic
background
- Athlete, pregnant or lactating women not correct
1
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2) Measuring body composition
- Body fat (adipose tissue)
- Lean body mass (lean tissue)
Error can be 3-20%
Methods
Underwater weighing
- Considered the most
accurate method.
Estimates body fat within
a 2-3% margin of error.
- Limitations: must be comfortable in water, requires trained technician and specialized
equipment, does not work well with obese people, must obstain from food before
Skin folds
- Involves pinching a person’s fold of skin at various locations on the body. The fold is measured
using a specially designed caliper. When performed by a skilled technician, it can estimate body
fat with an error of 3-4%
- Limitations: less accurate unless a technician is well trained, proper prediction equation must be
used to improve accuracy, person being measured may not want to be touched or may not want
to expose their skin, cannot be used to measure obese people (skin folds too large for the
caliper)
Bioelectrical impedance analysis (BIA)
- Sending a very low level of electrical current through a person’s body. Water is a good
conductor of electricity and lean body mass is made up of mostly water, the rate at which the
electricity is conducted gives an indication of a person’s lean body mass and body fat. 3-4% error
- Limitations: less accurate, body fluid levels must be normal, proper prediction equation must be
used to improved accuracy, cant exercise or eat before
Dual-energy X-ray absorption (DXA):
- Very low level X-ray to differentiate between bone tissue, soft (or lean) tissue, and fat (or
adipose) tissue. Lying for about 30 minutes on a specialized bed fully clothed, with all metal
objects removed. 2-4% error
- Limitations: expensive, requires trained technician and specialized equipment, cannot be used
for extremely tall,short or obese people
Bod Pod
2
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Document Summary
Biol 380 lecture 10 (done before lecture 9) energy balance and body weight. You can achieve and sustain without constantly dieting. Compatible with normal bp, lipid level, glucose tolerance. Promote good habit and allow to participate in regular physical activity. Underweight: having too little body fat to maintain health. Overweight: moderate amount of excess body fat. Obesity: excess amount of body fat that adversely affect health. Morbid obesity: body weight exceeds 100% of normal, high risk of serious health problems. How to evaluate body weight: bmi index or quetelet"s index: ratio of body weight square of height. Conversion factors: 1 kg = 2. 2 lb, (m) = 0. 0254 x inches. Type 2 diabetes, high bp, heart disease bmi over 30. Bmi neither tells how much body mass composed of fat nor where is excess fat on body. Not a fair indication for people above 65. Cannot reflect muscle and bone growth in children.
