T Nation

BF and Weight Formula For Contest


Thanks for taking the time to read this. We are going to be having our own weight loss / BF% loss contest at my work. In order to make it fair we needed to come up with a formula. I wanted to run it by all of you to get your thoughts. First some prerequisites. The contest is approx 12 weeks long. Each person is putting in $50. You will have your weight and BF% taken at the beginning and the end. Pretty simple. The winner gets half the money and the rest goes towards a party for the rest of us. Or I was going to propose we give it to charity. So I wanted to get your thoughts on the formula. Here goes.

First Weigh In - Final Weigh In = Total Weight Lost. In order to keep everyones weight on the same level we need to come up with a %. To do that we divide the Total Weight Lost by the First Weigh In

Next is BF%. We use the same concept. First BF% - Final BF% = Total BF% Lost. Again we need to change this to a percentage of the original. To do that we divide the Total BF% lost by the First BF%. This gives us the % of BF lost based on the original BF%.

So now we have two numbers. Since there can only be one number I was thinking about just averaging the two. I am unsure if this would be fair. So my questions are is my formula logical or am I just way off base? Second, would it be fair to average the last two numbers? Thanks again for taking the time to read this. All suggestions are welcome and I have never claimed to be a math genius.


You do realize then that the likely winners of this will just bloat up before contest and then lose all the water plus some fat during the contest.

Just saying that total weight lost is a piss poor measurement of accomplishment in terms of body composition. Mixing BF into the equation helps, but someone could easily lose just because they retain more muscle than the next guy who just starves and does cardio.

I would slant the BF measurement more, although in thinking about it that would still benefit the overly fat contestants.

How is a person starting at 15% going to ever beat someone who is at 25%?


cheack the hotrox competion posts they had some good ideas for competitions like this


You want to emphasize the body fat loss, I'd think, but you also want to adjust for starting body fat. Let's agree that larger scores are better.

w = weight lost
f = fat lost (expressed as a decimal)
e1 = starting bf% (expressed as a decimal)

100wf/(e^2) is decent, because larger changes in weight and fat will lead to larger scores, but people who started out leaner won't be penalized too much.

Let's say you started out at 250 pounds with 25% bodyfat. You lose 50 pounds and end up at 15% bodyfat--completely unrealistic for a 12 week contest, but I'm just picking round numbers here. Your score has w = 50, f = .1, and e = .25, which leads to a final value of 8000.

On the other hand, if you started at 220 with 10% bodyfat and drop down to 200 with 6% bodyfat, you have w = 20, f = .04, and e = .1, for a score of 8000.

Play around with the formula a bit and you'll see that it does reward pretty fairly.