Mysterious muscle/fat percentage switch. Any ideas?

tuckahoe88

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!

Okiludy

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

machine error margin. forget about it.

sijomial

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

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