A body-fat scale (which looks like your average bathroom scale, but measures electric conductance instead of weight) is the most affordable, practical way for you to keep an eye on your fat without getting help from someone else. But even top-rated scales make so many assumptions that you can’t trust the number they give you. So does that make them a gargantuan waste of time?
Not necessarily—provided you use your body-fat scale to measure changes in body fat.
Used this way, a body-fat scale lets you judge the success of an exercise plan or the toll of an expanding waistline. To use this strategy, you need to make sure you get a consistent reading. Here are some tips that can help:
• Watch your water intake. The amount of water in your body can dramatically change the reading of a body-fat scale. The best idea is to measure your body fat at the same time of day, at least one hour after drinking or eating, and definitely not after exercise. Consider making it part of your morning routine.
• Adjust the settings. For example, many scales have a specific profile for athletes or children. If you pick the right settings, the scale is more likely to make the right assumptions for your body and give you a more accurate reading.
• Don’t compare people. You and your friend may use the same scale, but it’s not fair to compare the numbers. Minor differences between the two of you can skew the results in different ways. Similarly, it doesn’t make sense to compare your own readings on different body-fat scales.
• Get a baseline. If you get the chance, measure your body fat with a more reliable method—for example, a skinfold test or an underwater weighing—then compare that result with the reading on your scale to figure out a basic frame of reference for how accurate your scale is.
Source of Information : Oreilly - Your Body Missing Manual