Fast Day calories and TDEE

This topic contains 6 replies, has 5 voices, and was last updated by dlroseberry 9 years, 10 months ago.

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Sallyboxerdog

4:27 pm
11 Jan 15
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Hi

I’m new to 5:2 and the forums so apologies if I’ve posted this in the wrong place.

My TDEE works out at 1600 and I’ve seen posted elsewhere in the forum that your Fast Day calories shouldn’t exceed 25% of your TDEE. This would make my FD calorie allowance 400, not the 500 recommended in the book and elsewhere in the forums. As you know 100 calories makes a HUGE difference to a FD and I would rather stick to the 500!. I haven’t got a lot of weight to lose, approx 11 lbs and want to maximise my chances. What do experienced fasters think?

Thanks
SBD

lovercomeback

1:08 pm
12 Jan 15
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Hi Sallyboxerdog. I am writing from my mother’s experience and not mine (just started and I agree with what she has told me given my reading):

You should stay at the 500kcal mark. As you said it can make a big difference. She was very kind to herself in the beginning, so didn’t worry if it was 500-600kcal. Overall her loss was 4st 4lbs. On non fast days she did not count calories and did not worry about the food she ate, as her tastes defer to the healthier foods anyway.

When she came to her final 10lbs that she wanted to lose (she is 5’4” and 120lbs) she just watched her non fast days more carefully. She eats an average 2000kcal on non fast days and when fasting eats the full 500kcal (although more strict about the type of food the less weight she had left to shift).

This was with no exercise and enjoying wine and a bacon roll at the weekend, crisps weren’t off the menu etc.

My TDEE like yours works out at 1600 on this website, and 1300 on others. I wouldn’t be happy about cutting my non fast, as it is little as it is, especially while keeping my calorie intake so low on non fast days – 1300-1600.

My mother would say, you should be eating more on your non fast days to make the fast more efficient and to not induce any starving. She says if you trust in the process it will come off.

I would say, try it for two weeks at 500kcal on fast and 1600 on non fast. Eat meals that are abundant in good protein and fibre and take your measurements and weight loss. If you see no change then alter it by the 100kcal for two weeks (essentially 4 fast days) and take measurements again. Keeping in mind that for maintenance you will have to continue your diet at 1600kcal on non fast days and once a week will have to do 400kcal if that’s what you choose.

Both of us feel that for your sanity, maintenance might be better on the higher calories.

I would expect results both ways.

Hope you get the results you want!

x

lovercomeback

1:10 pm
12 Jan 15
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The references for this post come from personal experience and wisdom from my mum, the stuff I have read thus far, and my understanding of how the body burn glycogen, goes into ketosis and so on.

My mum has lost and maintained her weight for 2 years now.

I wish I had converted earlier.

Amazon

2:57 pm
12 Jan 15
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Eating more on a non fast day does not affect the efficiency of the fast, and eating less than your TDEE will not induce starvation mode.

lovercomeback

3:25 pm
12 Jan 15
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Hi Amazon,

Could you possibly talk me over how this works as I am calorie counting at the moment and would like to stop.

If I eat normally on a non fast day but don’t over indulge in bad foods, I can come in anywhere between 1800-2200kcal. My BMR is 1300 odds and my TDEE 1600 odds (1300 on some site calculators).

I understand that using maths, if I eat 500kcal on fast days and not watch what I am eating I will have a calorie deficit equating to 1lb per week (all done very roughly).

If I am to eat 1/5 of my TDEE that would be roughly 320kcal. So at a deficit of roughly 3000kcal I would lose up to 1lb per week.

But overall, I would be reducing my intake by a greater amount in the week. Either way I would lose weight. But I do have reservations about my BMR coming up at 1300 and my TDEE coming up as the same on some calculators…as this could mean I would be on my BMR most days if I eat that low.

Media diet coverage tells us that constant low calorie will not have the same effect, and the book somewhat agrees with this.

I am wondering, in your experience which is more effective for weight loss?

Thanks in advance.

simcoeluv

5:02 pm
12 Jan 15
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Hi lover and welcome:

This will answer most of your questions: https://thefastdiet.co.uk/forums/topic/the-basics-for-newbies-your-questions-answered/

Number 4 explains TDEE.

There is no such thing as starvation mode – see FAQ, above.

Good Luck!

dlroseberry

12:05 am
16 Jan 15
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Hi Lover,

There are two competing ideas. One is that that dieting is a simple thermodynamic calculation and that the body’s metabolic rate is completely unresponsive to calorie intake, almost no matter what. The other idea is that lowering your intake of calories just might lower your body’s BMR, or otherwise cause you to need fewer calories to maintain weight.

In my opinion, there is not compelling research to answer this question in humans simply because it would require keeping many people confined for a long period so that the experimenters could reliably control dietary intake and then deduce calories burned by weighing. The experiments I’ve seen are either very short term or have poor control over the variable of consumption. This is a problem with all human dietary research.

Regardless, constant calorie restriction does work for some people very well and would obviously work for everybody if calorie intake is low enough. The question is whether the intermittent part of IF is anything more than just logistically easier to accomplish than constant calorie restriction. I don’t know the answer to that. But for me and most people here, it is easier.

I would advise that you start with something like a 300 calorie fast days and non-fast days with low fat, high fiber, high protein kind of foods, but no counting. Don’t go hungry on non-fast days but try not to binge either, if your an emotional eater (at least that why I binge sometimes, I think it is anxiety). See how that goes for a month or two to see if you lose weight. Then you can decide what you think about possibly going to water only, counting on non-fast days, or going to 4:3, or just staying with it. If it was me, I’d go to water only or 4:3, before counting on non-fast days if I had to to lose weight. But I’ve never had to except once or twice to 4:3 to nudge myself off a plateau.