content) than it does through fat mass (which does not contain water). The
scale uses a mathematical formula to calculate body fat percentage from
the speed of the electric current passing through the body.
Is the scale accurate?
The scale does not have the same level of accuracy found in body analysis
equipment used in scientific laboratories and some clinical settings. It is
designed to be a practical and reliable tool for monitoring body composition
as a guide only.
It is important to note that a number of factors affect body water
measurements regardless of the sophistication of equipment used. Body
water fluctuates a lot more than body fat does (see below and ‘Using the
scale for tracking progress’). Being under-hydrated (e.g. immediately after
exercise) will give you a higher fat percentage reading than when you are
fully hydrated.
It is therefore advisable to check your body fat percentage under similar
circumstances on each occasion e.g. first thing in the morning after passing
urine and before eating or drinking anything.
A range of circumstances can alter (increase or decrease) body water
content:
• Eating and drinking (including alcohol)
• Stage of the menstrual cycle
• A sauna, hot bath or shower
• Intense exercise
• Fever
• Extreme environments (hot or cold)
Just like weight measurements, it is advisable to pay more attention to
changes in body fat percentage over a period of weeks and months. Daily
body fat percentage measurements may fluctuate considerably due to
short-term changes in body water from day to day.
I’ve lost weight but my body fat percentage hasn’t changed much
The proportion (percentage) of body fat relative to total body weight may
not decrease much in the very early stages of any weight loss plan. Calories
from body carbohydrate stores (called glycogen), and water bonded to the
glycogen, are released following reduced calorie intake.
