The FastDay Forum

I am not sure how accurate scales with impedance readers are for body fat determination but if I believe my scales I have lost almost exclusively fat. I started 5:2 on April the 8th. On the 7th of April (my weigh in day is Sunday) I was 208 lbs (94.55kg) and my body fat was 29.5"(according to the scales). Yesterday after 3 weeks of 5:2 and 6 fast days I weighed 201lbs (91.36kg) and my scales said my body fat was 26.3% (all of which I am over the moon about). If my body fat has dropped 3.2% and I started at 208 lbs that would be 6.6lbs of fat. Given I have lost 7lbs it seems unbelievable to me that almost all of it would be fat. So maybe I have the math wrong or maybe the impedance readers are not so accurate but I am still thrilled

Anyone else have a similar experience?

Around 70% fat and 30% fat free mass (FFM) is typical of weight loss, though some of the Alternate Day Fasting (ADF) studies show good retention of FFM.

208 * (100 - 29.5) = 146.6 lbs FFM

201 * (100 - 26.3) = 148.1 lbs FFM

does point to you preserving FFM.

I don't have body fat scales so I can't confirm your experience from mine, but Dr M has said that with 5:2 up to 90% of the weight loss is fat. So even if your results are not 100% accurate (and they may be) they do seem broadly plausible to me.

There definitely are people here with body fat scales so it would be interesting to compare with others, I agree... There might also be some differences in fat loss % depending on BMI, I think.

Thanks Phil and Dominic,

My starting BMI was 29 and it is now 28.14. When I have dieted before I have not seen the preservation of FFM so that is really pleasing. It would be good to see if others have had the same experience. I had thought that a lot of the weight loss was just fluid as I did lose 4lbs the first week but almost needed a catheter that week because I was hitting the bathroom so often.

[wildmissus]

Interesting. I bought Omron body fat scales on 4March at which point my body fat was 40.9%, BMI 27.7, on 27th April by body fat was 41.0%, BMI 26.1. Weight loss in that period was 11lb, no change in fat %age. Not sure what to make of that.

Judging form the fact that we mostly lose inches and not too much weight, I think that Dr M is right.

The percentages measured by impedance can vary quite a bit depending on hydration levels and whether you have eaten/exercised lately. Some of those scales can measure hydration % too and it's useful to check that it's at a similar level to your last reading.

For example, I was curious last week about my BF %/hydration towards the end of a fast day - it was 26.8% BF and a hydration level in the low 50s. The next morning, before eating but after a loo visit, it was 28.6%BF but the hydration was in the high 40s. I was also 1.2kg lighter.

So... which to believe... I'd like the weight from the morning and the BF from the night before in an ideal world!

But if your weighing conditions and times are broadly comparable, then using the BF% as a trend guide, can't hurt.

Thanks Applespider

I normally weigh first thing on Sunday morning but my scales do not measure hydration so I am not sure if I was equally hydrated at both those times.

Wildmissus those results don't seem right. I am not sure how you could lose that much weight and not have bodyfat change. Do you weigh at a similar time on the same day as Applespider suggests? Do your scales measure hydration?

Interesting. I bought Omron body fat scales on 4March at which point my body fat was 40.9%, BMI 27.7, on 27th April by body fat was 41.0%, BMI 26.1. Weight loss in that period was 11lb, no change in fat %age. Not sure what to make of that.

I seem to have the same problem Wildmissus. I also bought the Omron scales and I've lost about 9lbs so far and an inch off my waist, but the fat percentage is still hovering around 45 and the visceral reading hasn't changed at all, still shows 10. Very strange!

The first time I heard about this was in an interview Dr M did with an Australian radio program a while ago. It is still available on their website. He says the weight loss is 100% visceral fat.

http://www.abc.net.au/local/stories/201 ... ite=sydney

I looked on the choice website regarding these kind of scales. Th view seems to be that hey ar very inaccurate. Although I m curious I am not racing out to buy a pair.

[wildmissus]

The numbers on the scales with regards to body fat don't worry me as I know they are inaccurate but I was just hoping to use them to see a downward trend.

Evie, my visceral fat has gone from 8 to 7, which does please my very much especially as I am apple shaped and from what mullumgirl has mentioned that's good. I must look into the no change thing re the body fat thing a bit more.

In the interests of research, are there any observations from those who have been monitoring their body fat% levels as to their intake of protein generally and especially on fast days?

It has been suggested (see this topic in the nerdy stuff) that higher protein intake is better for losing more fat and less other stuff, though how or if this applies to 5:2 is unclear.

[carorees]

It can't possibly be 100% visceral fat! "May target visceral fat preferentially" is as far as I would go. Looking at people's posts it's clear they have been losing fat from other places than around the viscera. There will almost always be some loss of muscle as it takes less effort to move a lighter body around so unless you do weight training some loss of muscle is inevitable as it's not needed by the body. The aim is not to lose more muscle than that dictated by the lighter body. So 90+% fat but less than 100% is what is expected.

Wildmissus those results don't seem right. I am not sure how you could lose that much weight and not have bodyfat change. Do you weigh at a similar time on the same day as Applespider suggests? Do your scales measure hydration?

Water isn't tightly regulated, so +/- 2 lbs daily fluctuation isn't unusual.

I can pee a pound easily, for example. One pound weight loss, fat would go up as a percentage of BW.