The FastDay Forum

Hi

I have a set of scales that measure body fat - I know they are not 100% accurate but I use them to track up and down trends in my body fat level.

This is my first week of 5:2 - and the first day I lost 2lbs (I know this will probably average out to 2lbs for the whole week) - but my body fat level rose. I understand the principle - lower weight but amount of body fat stays so the same, so as a percentage it is higher... but will I see body fat decrease overall on this diet? I though one of the advantages of the 5:2 was that you maintained muscle and burned fat?

[wildmissus]

Hi there and welcome. Take a look at my tracker. This week I lost weight and gained fat other weeks I have lost fat and gained weight. My fat loss has been extremely slow but the trend is down. I'm not sure entirely how it works but as you already mentioned the scales that measure body fat at not very accurate. I have however noticed that the weeks where I have exercised a lot but maybe eaten too much is when the fat goes down and the weeks when I've been lazy but eaten healthily is when the fat goes up. That doesn't really answer your question but try and look at it as long term thing.

hi @twofish, and welcome to the forum!

I would say one fast would be way too short a time to reach any conclusions on body fat and weight. Just too variable and unreliable to measure. You don't say how much your bf went up, but I would just relax and see how you go over, say, a month. If you're worried, you could try increasing your protein intake a little - one of the other strings at the moment, entitled "Dr Mercola", has an interesting discussion on what our protein intake should be on feed days and fast days to minimize muscle loss.

Good luck with your fasting!

I've got some body fat measuring scales and I have NO idea whether to believe them or not because they are all over the place - I suppose the general trend is down but they're never very comforting when I get on them because they vary wildly.

I have body fat scales and when I started fasting they wouldn't even measure my body fat as it was too high. They can only work if your body fat is below 50%, so I have no idea how much above it I was. but I'm now down in the mid 40's yet have more muscle according to the scales than before.

Thanks for all the comments.
Yes, jools7 too early to say - but I did the 5:2 in January for 4 weeks and noticed the same thing...! I will definitely look at the Dr Mercola link.

wildmissus - that's interesting... and puzzling.

loversghost - I'm with you. I never really know whether to trust the body fat measurement but as long as they show some kind of trend then I'll see how it goes.

Julieathome - well done on getting your body fat level down... that's very encouraging and inspirational.

week 2 approaches - onwards.

[carorees]

The percentage of body fat will always depend on the percentage of water in your body so if you are dehydrated your body fat percentage will be up and if you have taken on a lot of water it will be down. At the start of any diet you lose a lot of glycogen (stored glucose) which is composed of 4 parts water to 1 part glucose so most of that 2lb will be water. After all in one week you cannot have eaten 7000 calories less than last week, hm? After one fast day you have only undereaten by approx 1500 cals which at most will have meant that you could have only burned half a pound of fat, but actually as it is the glycogen that you have mainly burned at the moment your body fat will have dropped only a tiny bit but your body water will have dropped a lot, hence the increase in fat %. But as you say the reliability of the fat % is questionable anyway.

You will lose body fat. According to my scales I have gone from being about 50% fat to only 30% fat.

To read more about the scales, weighing and measuring please read this article: how to measure success with intermittent fasting

I am very confused about the body fat percentage on my scale. Today it says 37.5% with a weight of 148.5 lb. It said 37% when I started this journey at 181.3 lb. So I'm over 32 lb lighter but fatter?
Do I need new scales? I have started some exercise this week but essentially I am sedentary. ?dehydration (fasted yesterday). Any advice @carorees or other science guru reading?

[carieoates]

Advice from me is always weigh for weight first thing in the morning. And body fat later in the day as everyone wakes up dehydrated. Mine can fluctuate from 36-39% fat

Thanks @carieoates, I am going to drink lots and measure later. If it's still a crazy number, out they go

Note your body fat percentage. Now dampen your feet with a wet wash cloth and measure it again.

See a big difference?

That's because the scale measures the change in skin resistance caused by moisture (or the lack of it).

Given a large set of measurements and a spreadsheet you could graph a fat-percentage trend line that would eventually become meaningful. That's what the Progress Tracker does for you here except that its uses weight.

Having only one or two fat scale percentages is almost as useful as having damp feet.

I have used a Tanita body fat scale for years. I only weigh immediately after waking, and as others report, the readings are all over the place.

When I had my body fat percentage measured with calipers some years ago, it was much lower than what the scale shows.

Obvious problems are the hormonal fluctuation of water content, boob size, salt content, and even the ambient temperature. In winter I'm much less likely to retain water than in summer.

My scales suggest I haven't lost any body fat, but I doubt I have lost 11+ pounds of water or any significant amount of muscle mass over the almost 5 months I've been doing 5:2.

I have stopped putting the BF% into my tracker because it seems so useless.

Even waist measurements fluctuate a bit with glycogen since your liver will plump up with more glycogen and shrink with less. When I stopped my metformin, which cuts back on liver glycogen, my waist went up about .5 in. When I started it again, it dropped back.

I'm sure @carorees has a really good body fat calculator somewhere, based on neck and waist measurements as well as weight, I just can't find the link!
My Tanita scales do body fat too, 15% the morning, 11% later in the day. I have the calipers too, but I have so little fat that it is off the scale for my (old) age.
Realistically I think I'm around 13 - 14%, low because I do a lot of sport and have a lot of muscle. So the scales aren't totally useless!

Just an update..at the end of the day with lots of hydration:
Dry feet: 35.9% BF
Moist feet (as suggested by@ADFnFuel ): 35.9% BF

No difference, slightly better than this morning and overall, very demoralizing. I guess I need to focus on strength training of some sort if I'm to reduce my %BF.

I guess I need to focus on strength training of some sort if I'm to reduce my %BF.

Physical exercise/sport is great fun and good for your head as well as reducing your body fat. Nothing to get down about!