Mysterious muscle/fat percentage switch. Any ideas?

tuckahoe88
tuckahoe88 Posts: 33 Member
in Goal: Gaining Weight and Body Building
Greetings MPF folks! I am a long-time board lurker. MPF member since 2012. This is my first question on one of these boards:

I had a bodpod analysis last week and received some unexpected results since my last analysis 3 months earlier. My “fat-free weight” dropped ~5 pounds and my “fat weight” correspondingly increased ~5 pounds. My total body weight stayed within one pound of where it was 3 months ago. It was as if my muscle and fat decided to change places ;)

I reviewed my food and exercise logs during the past 3 months and don’t understand what caused the shift. I did increase my running a bit, but I did not stop weight training during that period. My calorie intake was stable.

I have been maintaining my weight (127-130) for several years and am regimented in what I eat (I don’t get tired of eating the same things every day). I get a lot of exercise (cycling, running, swimming, lifting, hiking, kayaking). Middle-aged, female, 5’5”. Three months ago, I was ~13% body fat. Same as it was the year before. It is now ~17%.

I’m not particularly worried and am satisfied with my physique and energy. But I’m mystified about what I consider a fairly short-term change in composition after having been uncannily stable for a couple of years.

I’ve read (on these boards) that BodPod analysis is certainly not 100% accurate nor is bioelectrical impedance (which corresponds to my bodpod results quite closely, though). I use these readings for general trends and for curiosity’s sake, I guess.

I should add—although I’m not sure it has any bearing whatsoever on my body composition switch—that I was experiencing terrible stress during that 3 month “switch” period (which may explain an increase in running, perhaps). I dropped a couple of pounds during that time, but have since gained them back. They just apparently came back in different places ;)

Can any of you helpful folks offer any insight or hypotheses? Very much appreciated!

Replies

  • Okiludy
    Okiludy Posts: 558 Member
    I would go with margin of error. More importantly if you stayed within 1 pound and and low body fat for a woman why bother?
  • misnomer1
    misnomer1 Posts: 646 Member
    machine error margin. forget about it.
  • sijomial
    sijomial Posts: 19,809 Member
    When I was losing weight I went for 6 monthly BodPod tests. Mostly they gave pretty believable numbers and trends but I had one test result which was completely off the wall.
    Fat % up and lean mass % down when my waist measurement had gone down and chest/arm/leg dimensions went up together with noticeably better muscle definition/vascularity/leanness. Really dented by confidence in the method.

    Would have carried on using my 4 point BIA scales which gave a trend and numbers that matched the BodPod pretty closely but when they died I didn't bother replacing them.
    I gave up trying to estimate a BF% number that didn't really have a lot of significance for me and switched to performance metrics instead. If I can ride faster, lift heavier and not clear any beaches when I take my shirt off, then that's fine by me.

    BTW
    13% is remarkably low for a female.
    Stress can lead to water weight gain/retention, but would have thought that more likely to mess with BIA analysis more than BodPod air displacement analysis method though.
  • tuckahoe88
    tuckahoe88 Posts: 33 Member
    Thank you all very much for your helpful responses. This may be the one time in my life when a machine was possibly at fault and not me. Sijomial, you bring up a very good point about stress. Thanks also for telling me about your own experience. Much appreciated! Enjoy the weekend folks :smile:

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