Fat loss challenge at my gym

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slbbw
slbbw Posts: 329 Member
in Fitness and Exercise
My gym is doing a fat loss challenge for January and the owner asked for my opinion on the most fair way to calculate across old young male female etc.

So he definitely want to use BF% and will be using a handheld bio-impedance for the measurement. Obviously the accuracy of this device is debatable, but using the same device at the relative same time of day should at least be able to get an accurate trend.

So the question is how to make it fair. Is just calculate BF% difference between start and end of month enough, or is there a calibration that is needed. Does it need to be a percentage loss? or should it subtract the minimum BF% for men and women? Account for age?

Replies

  • CSARdiver
    CSARdiver Posts: 6,252 Member
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    Accuracy in this case isn't as relevant as precision. To be as precise as possible measurements should be taken early in the morning post-voiding and pre-eating/drinking.

    The impact of age is going to be minimal and any attempt to correct bias is much more likely to create bias.

    Depending on the variance of participants a percentage loss would be the most "fair".
  • 4legsRbetterthan2
    4legsRbetterthan2 Posts: 19,590 MFP Moderator
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    I would at least do different gender and age classes to make it more achievable for different groups, they can feel like they are competing against people they have a chance against.

  • BuiltLikeAPeep
    BuiltLikeAPeep Posts: 94 Member
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    I know this probably won't work for the thinner participants, I'm just throwing the idea in- but what about percentage of inches lost?
  • kshama2001
    kshama2001 Posts: 27,897 Member
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    BF is easily manipulated but since the owner is probably going to run this challenge regardless, I would recommend a % lost.
  • mom23mangos
    mom23mangos Posts: 3,070 Member
    edited December 2019
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    So when we did a family bet, I based it on % of goal met. But that meant that technically everyone could be a winner. Everyone picked a different goal. For my husband, son and his GF I think they picked something like 25lbs which was reasonable considering they are all technically obese. I picked 10lbs or 5% BF reduction. We all put in money and the pot would be split by whoever achieved their goal in the timeframe or else the person who got the closest. I kept a running tally of % of goal complete to see who was in the lead.
  • Duck_Puddle
    Duck_Puddle Posts: 3,224 Member
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    I don’t think there’s a fair way to do it.

    But based on the way those devices measure (and my Bf% “changes”), I would suggest the best strategy is to go in for the initial measurement very dehydrated, at a low point for weight (lower denominator, higher %, plus less water leads to falsely high readings)

    The day before the final measurement, eat very heavy (literally) carbs and enough salt to kill a horse. You will bloat up like a blimp-but your measured BF% will be much lower (because your weight will be higher (higher denominator - lower %) and more water causes falsely low readings). I do this weekly-“lose” 3-4% BF overnight when I “gain” 4-12 pounds of water & food.

    Percentage of body weight lost would be at least a reliable measurement (although would still bias against those with lower weight- but slightly less than BF).
  • sgt1372
    sgt1372 Posts: 3,977 Member
    edited December 2019
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    No BF% measurement device is completely consistent or reliable - there's always some degree of error, even for DEXA and hydro which are the best of the bunch and electrical impedance devices the worst.

    IMO, the best way to measure "fat loss" for the competition would be to use the change in BMI or the % of wt lost during the competition using the same scale to weigh all of the contestants at the start and finish and, in the case of BMI, the same height measurement device (or just marks) located somewhere posted on a wall in the gym.

    Ideally, the scale would be the type you find at a doc's office that has a means of measuring both your wt and height built into it.

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