What is BIA and Body Fat?
Bioelectric Impedance Analysis is a way to estimate the amount of body weight that is fat and non fat by measuring the resistance of a harmless electrical current as it moves through the body. The less fat a person has the easier it is for the electricity to flow through the body.
Fat is anhydrous and is a poor conductor of electricity. Muscle is comprised of 70-75% water, and serves as excellent conductor of electric current.
Bones, organs and blood vessels are types of body tissue and body mass with a high water content that also serve as excellent conductors of electric current.
The body fat mass and body fat percentage is calculated by programmed formula that includes the following six factors: electric resistance, height, weight, age, gender and body type (standard or athletic).
- Ratio of the body constituents:
Body fat percentage refers to the amount of body fat mass in relation to the total body weight described in a percentage.
Body fat percentage(%)=
{body fat mass(lbs.) / Body weight (lbs.)}
Body Fat Percentage Fluctuation Chart
Body Fat is affected by the change of water content in the body. The diagram below illustrates the fluctuation of body fat percentage throughout a typical day. The changing pattern of body fat percentage varies for each person and only demonstrates the common factors that can significantly increase fat index readings.
Recommended times for measurements are:
- Directly after waking up.
- In the afternoon, about 2 hours after lunch and before eating dinner or bathing.
- Before lunch, about 2 hours after breakfast.
- Before going to bed, about 2 hours after dinner.
Suggestions to Optimize BIA Results
Personal level of hydration as well as blood circulation levels may have an effect on body fat readings. The following situations could affect the BIA reading.
| Cause of fluctuation | Fluctuation Periods |
|---|---|
| Water and food intake | 1 to 2 hours after eating breakfast, lunch or dinner. |
| Changes in level of blood circulation. |
After taking bath or shower, immediate after exercise, in extreme environments (warm or cold), or during extreme illness and fatigue. |
| Posture change while holding electrodes. |
Moving from an up-right standing position to a downward or crouched position during the measurement. |
Understanding the fluctuation of body fat percentages within normal daily activity will assist the user in scheduling a more accurate period of time for body fat screening.
The following physical conditions can significantly alter body fat percentage:
Readings should NOT follow:
- Vigorous exercise
- A bath or sauna
- Drinking alcohol
- A meal or drinking a large amount of water.
The following group of people may have significantly different body fat percentages:
- Adolescents in growth stage
- Elderly people or post menopausal women
- People with fever
- People who have swelling
- Patients with osteoporosis
- Bodybuilders or professional athletes
- Patients undergoing dialysis
IMPORTANT: Always initiate measurements under controlled settings; such as same time of day, at least two hours prior to or post eating, and before exercising.
Procedural Guideline for BIA
The accuracy of BIA depends solely upon the user’s adherence to these specific guidelines.
- Slightly moisten hands with sanitizer.
- Stand with both feet shoulder with apart.
- Place the entirety of your palm over the top
and bottom of the electrodes with thumbs
resting above or around the side.
- Holding arms straight out at a 90 angle to your body, firmly grasp both electrodes and attempt to remain as still as possible until the BIA measurement is complete.
- Avoid the following:
Rating System for Assessing Current Level of Body Fat Percentage for General Health
ADULT MALE |
ADULT FEMALE |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Age |
Excellent |
Good |
Average |
Poor |
Age |
Excellent |
Good |
Average |
Poor |
|
19-24 |
10.8% |
14.9% |
19.0% | 23.3% | 19-24 |
18.9% | 22.1% | 25.0% | 29.6% | |
25-29 |
12.8% |
16.5% |
20.3% | 24.4% | 25-29 |
18.9% | 22.0% | 25.4% | 29.8% | |
30-34 |
14.5% |
18.0% |
21.5% | 25.2% | 30-34 |
19.7% | 22.7% | 26.4% | 30.5% | |
35-39 |
16.1% |
19.4% |
22.6% | 26.1% | 35-39 |
21.0% | 24.0% | 27.7% | 31.5% | |
40-44 |
17.5% |
20.5% |
23.6% | 26.9% | 40-44 |
22.6% | 25.6% | 29.3% | 32.8% | |
45-49 |
18.6% |
21.5% |
24.5% | 27.6% | 45-49 |
24.3% | 27.3% | 30.9% | 34.1% | |
50-54 |
19.4% |
22.7% | 25.6% | 28.7% | 50-54 |
26.6% | 29.7% | 33.1% | 36.2% | |
| 54-59 | 20.2% | 23.2% | 26.2% | 29.3% | 54-59 | 27.4% | 30.7% | 34.0% | 37.3% | |
| 60 | 20.3% | 23.5% | 26.7% | 29.8% | 60 | 27.6% | 31.0% | 34.4% | 38.0% | |