The FastDay Forum

I have had years of diets ruling my life and that has caused most of my issues with food. What I love about this is I don't really have to think, or hunt or special foods or deny myself the things I love. All I have to do is fast twice a week which I mostly can do and be sensible the rest of the time. (...) I now eat proper food made by me and have discovered I love cooking! If looking at all the science does for you great, for me, I need a more simple approach.

Bobshouse, I love the science, but I wholeheartedly agree with your approach!!!! Enjoying food and cooking instead of fighting and fearing it sounds like a major benefit to me!

"We don't know what really happens to our RMR with intermittent fasting. I looked for articles but could not find any."

ADF results at http://ajcn.nutrition.org/content/81/1/ ... nsion.html show a non-significant reduction from baseline (the weight declined) and no difference between feed day and fast day.

Baseline Day 21 Day 22
RMR (kJ/d) 6675 ± 283 6292 ± 268 6329 ± 260

divide by 4.18 for calories

I'm just wondering what is the scientific basis for the whole 'reducing cals reduces your metabolism' rumour. Is it simply a misunderstanding of the fact that the less you weigh, the slower your metabolism?

It's largely a psychological defence of overeating, in my opinion.

Some studies show reductions in RMR beyond what you would expect from weight loss, others not. Inherent errors in measurement are often bigger than the effect people claim to observe, and the effect is seldom bigger than a Twix a day.

The more interesting angle is perhaps not the "metabolism" but the reduction in energy used for activity - either through improved efficiency or through less activity. If you're weak and hungry you flop on the sofa rather than doing the cleaning, that kind of thing.

Measured metabolic rates below 1200 cals a day are fairly unusual, below 1000 are fairly rare and usually found in light weight anorexics.

[carorees]

Also once you lower your metabolic rate (if the paper I highlighted is correct) the lowered rate persists for at least a year, so you become trapped in a situation of permanent restriction. Very few people are able to maintain such a restriction so yes you might lose more weight but if you gain it back you're back where you started. The main thing about 5:2 is that it is sustainable. Any weight loss system that does not result in keeping the weight off is not only pointless but actually makes people less healthy afterwards than they were before they started.

4:3 so far is not showing any advantage over 5:2 but that might be due to the characteristics of the people doing it.

The Camps study has a 0.27 MJ/day adaptation at the end of the VLC diet. that's 65 calories a day ie half a finger of Cadbury's Fudge or 6 cashew nuts.

You can see the variability in individual results from the figure below :

[carorees]

That's interesting Phil. It looks like some people can cope with a very low calorie diet while others show a notable drop in RMR. Which is not surprising.

Of course the change in RMR is not the only factor that may result in people not losing weight on a low calorie intake.

Unfortunately, it's not possible a far as I know to predict what effect going down to 1200 cals or less on a feast day will have, but I still think that the sustainability factor is key.

This is very comfusing. Years ago I could loose weight pretty easily and I kept if off for many years. But as I got older.....mid 60's now.....I put weight back on and have not been able to lose it. All kinds of extreme dieting would result in maybe 1/2 lb. loss a week. And I hate all the constant counting calories etc. and couldn't keep it up. But the 5:2............. I have been doing 4:3 and 5:2. More 4:3's and have lost 12 lbs in about a month. I walk 3 to 4 times a week (brisk) and do the exercise bike 15 to 30 minutes 2 to 3 times a week with 3 "power bursts"....per Caroline's advise. I feel the exercise is keepng my metabolism up. I eat much healthier on my feed days. But do have treats when I want them. But honestly I do not want them often. This is all amazing to me. If things change I will see, but now I don't want to change a thing. It's working so well for me and it's such a surprise. And yes. It's very sustainable WOL.

That's interesting Phil. It looks like some people can cope with a very low calorie diet while others show a notable drop in RMR. Which is not surprising.

about 1/4 to 1/3 of the subjects had higher RMR after 8 weeks of VLCD, as far as I can tell by counting squares.

Unfortunately they mixed men and women, which increases the s.d. for no useful reason.

Newbie here - i am on my second week of the5:2 plan, still feeling my way along. I have now done 3 fast days total using only one mid day 500 cal meal. Is there any reason not to split up the calories over the day - say 100 calories each mini meal? I think that will make it less tedious?
Also, should there be a quick drop initially or is this really a slow pound a week process overall (I know health benefits are hidden in there too) -

I am not really hungry on the fast day, but get dizzy and headachey.

Sandylee

That's worth a try too the 4:3 method rather than noting daily calorie intake, which I suppose is one of the advantages of this diet.

Thanks

I feel the exercise is keepng my metabolism up.

There is evidence that exercise induces autophagy which in turn maintains muscle homeostasis (He C, Bassik MC, Moresi V, et al. (January 2012). "Exercise-induced BCL2-regulated autophagy is required for muscle glucose homeostasis". Nature 481 (7382): 511–5. doi:10.1038/nature10758. PMID 22258505.) so it probably is doing just that. Another good reason for me to get up off the sofa!

No, it says metabolism slows by more than predicted from the body composition, so your metabolism is disproportionately slower after dieting down to 8st than if you had been 8st all along.

RESULTS:
The ratio of RMRm to RMRp decreased from 1.004 ± 0.077 before the diet to 0.963 ± 0.073 after the diet (P < 0.001)

RMRm = measured
RMRp = predicted

So if this is true, does that go some way in explaining why a lot of people find it hard to keep the weight off after losing? And hard to understand why anyone should be over weight by the lucky people who have the sort of metabolism that allows them to eat pretty much what they like (I have a couple of friends like that, grr)?

Newbie here - i am on my second week of the5:2 plan, still feeling my way along. I have now done 3 fast days total using only one mid day 500 cal meal. Is there any reason not to split up the calories over the day - say 100 calories each mini meal? I think that will make it less tedious?
Also, should there be a quick drop initially or is this really a slow pound a week process overall (I know health benefits are hidden in there too) -

I am not really hungry on the fast day, but get dizzy and headachey.

Sandylee

Hi Sandylee

Re: splitting up calorie intake on fast days - this seems to be a matter of what suits the individual. For maximum (potential, so far unproven) health benefits, it's probably preferable to save all calories for an evening meal, but for weight loss (judging by reports on this website) there doesn't seem to be any difference.

Re: being dizzy and headache-y, you may find these pass as you get used to this system of eating. Increasing water intake seems to help some people who suffer headaches, and the dizziness may (or may not) be helped by dividing your c500 calories into several mini-snacks over the day. It might also be worth checking how much sugar you are eating, and when, in case this is influencing your dizzy spells - but this is not my area of expertise, so others will probably have more helpful advice for you than I can offer.

Good luck!

[carorees]

Swedey, read this thread about how dieting results in weight gain. It's not just the metabolic rate but a load of other sneaky tricks that your body uses.
viewtopic.php?f=18&t=2687

But surely Caroline, the metabolism (i.e. energy expenditure) is the ultimately the only confounding factor? The rest are just what might make it harder for us to stick to the lower calorie input in the longer term.