When changing the percent body fat with a change in body weight the one constant is fat-free body weight.


percent body fat =

= (fat weight in kilograms) / (weight in kilograms) * 100%


weight in kilograms =

= (fat-free body weight in kilograms) + (fat weight in kilograms)


weight in kilograms =

= (fat-free body weight) * 100 / (100 - (percent body fat))


If there is a change in the percent body fat:


final weight in kilograms after change in body fat =

= (100 - (initial percent body fat)) / (100 - (final percent body fat)) * (initial weight in kg)


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