How do i?

IamOnMywayNow

Find out how much more weight to lose to be at a certain body fat%? I am currently 128lbs and about 30% body fat (got this from fat2fit using measurements) I would like to get 20% body fat. Is there a formula somewhere that will tell me this?

Never mind I think I got it figured out LOL I am not good at math so I thought I would ask. If I take 128 minus 10% this should give me 116lbs. Right?

BikerGirlElaine

[Hopefully it's OK to give just the mathematical answer -- someone will be along to flesh out all the reasons why the mathematical answer isn't necessarily accurate, true, or the goal to shoot for :flowerforyou: ]

If you were to keep all of your LBM and lose only fat, and if you are truly at 30% BF now, 113 would give you 20% BF. It might not be that simple, though, as there are a lot of things that can and do go wrong with those kinds of calculations. Going by what you see in the mirror is better.

Calliope610

Fat2Fit also has a calculator that figures your "goal weight" based on the desired BF%.

http://www.fat2fitradio.com/tools/ibw/

Custom Goal Body Weight Calculation

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You currently weigh 130 pounds with a body fat percentage of 30%. You would like to have a body fat percentage of 20%.

Based on this information, your goal body weight should be:

114 pounds

How did we calculate this goal body weight?

We took you current weight and your current body fat percentage and multiplied them together. (Weight X Current Body Fat %/100) to get how many pounds of you is actually just fat. In this case you are currently carrying around 39 pounds of fat. To get your goal body weight we work backwards and divide your lean body mass by one minus your goal body fat percentage. (Lean Body Mass / (1 - Goal Body Fat %/100). This calculation yields your goal body weight.

When you reach your goal, hopefully you have maintained your current lean body mass of 91 pounds.

SideSteel

I'll just add that depending on how things go, you will likely need to lose more weight than these predicted models suggest because you may lose fat free mass that is not necessarily skeletal muscle.

Sarauk2sf

Just to add to the above, those calculators can be highly inaccurate and you may well not be at 30%. They come out about 6 - 7% too high for me.