Body Fat % after workout

[Andy2]

Why does a scale drop my body fat percentage drop so dramatically after a workout? I'll literally move about 4% from pre to post workout. Does it have to do with the amount of water lost? Not a big deal, but I know it happens to my roomate and myself a lot, and I couldn't find anything on the web.

Thanks!

 

[MAR1984]

Bioelectrical Impedance Analysis or BIA is considered one of the most reliable and accessible methods of screening body fat. In conventional BIA, a person is weighed, then height, age, gender and weight or other physical characteristics such as body type, physical activity level, ethnicity, etc. are entered in a computer. While the person is lying down, electrodes are attached to various parts of the body and a small electric signal is circulated. Simply explained, BIA measures the impedance or resistance to the signal as it travels through the water that is found in muscle and fat. The more muscle a person has, the more water their body can hold. The greater the amount of water in a person's body, the easier it is for the current to pass through it. The more fat, the more resistance to the current. BIA is safe and it does not hurt. In fact, the signal used in body fat monitors can not be felt at all either by an adult or child.

Basically, how I understand it, more water = less resitance recorded = more muscle. Less water = more resistance = more fat.

But that seems backwords to what you're describing, unless you're drinking more waterduring your workouts than you lose. There could be more to it than just simple resistance, but I'm having trouble finding a detailed explanation.

Getting Accurate Readings with BIA Monitors
You must not be dehydrated - do not use first thing in the morning or immediately after a workout or after consuming alcohol. Use 3 hours after a meal and after voiding your bladder. Women may experience fluctuations with retaining water, and those on diuretics may see inaccurate readings. You need to weigh yourself without clothes.

and should tell you everything you need to know about BIA.



Basically, everything I'm reading says that all sorts of variables can effect accuracy and precision in testing body fat with BIA scales. My opinion would be to treat it as most recommend tracking weight - try to do it at the same time and the same conditions each time you check, and only bother noting the trend of the number, and not the number itself.

 

[Jeanette401]

When you lift weights you get small tears in your muscle fibers. These get filled with water, so you often have more water actually being stored in your system and you'll go up a little in weight as well. So, if you're going up a little in weight then I'd assume it's water weight from the workout and that's what leads to the change in the BF according to the scale. It's not 'real' BF change, just what the scale is using to measure.

 

[biggestloser105]

My bet would be on sweat. If my skin is even slightly damp when I use my scale, my body fat will be considerably lower. I even have to make sure I thoroughly dry my hands if I'm weighing myself after washing them. Of course all this would depend on your equipment.

Drinking water during your workout could also decrease your resistance.