The FastDay Forum

Ive searched around for the answer and it seems that <40 or 50 is considered fine, and will not trigger the body into breaking the fasting process.

As a 5:2er, this is quite important to me so would love to know the answer.. does anyone have any reliable facts or figures?

I am not sure about the science but there is a view that almost any calories at all will trigger munchies. I am currently trying to avoid all calories, including milk in tea and coffee, until suppertime. I can't honestly say for sure whether it is easier or harder (than having milk, I mean); except that the tea doesn't taste as nice of course...

[carorees]

No, I don't think there are any. Some of the IF gurus think 10 is enough!

They say that you can have 1000-2000 cals worth of stored glycogen, so that gets used first, then when you eat again it is replenished. So unless you go carb free or skip breakfast and lunch you won't be starting to burn fat until well into the fast, if at all. I strongly suspect that the headaches people get coincide with a failure to switch to fat burning when the glycogen runs low. So I don't know if we can even talk about breaking the fast in the way you mean (i.e. out of ketosis) for most of the time we are fasting. It all depends on how big your glycogen stores are.

So I can't answer your question. Sorry.

I don't think it's possible to answer the question without knowing what you mean by the fasting process. There is also no research based science on how many kcal you can eat on a fast day and when you can eat them.

The theory of hormesis

http://www.marksdailyapple.com/hormesis-how-certain-kinds-of-stress-can-actually-be-good-for-you/#axzz2KDGsw43r

says that by fasting, we're putting the bodies' cells under stress. Even when we eat our full quota of <500/<600 calories on a fast day, the cells are still under stress.

So, to answer your question, SuperFuu, I don't think you actually break the fast until you begin to eat normally again.

What do you reckon, folks?

[carorees]

B&W, I assumed SuperFuu was referring to ketosis because many of the other sites about IF are concerned with keeping carbs to a minimum in order to promote ketosis. These are the Paleo diet folks etc. Once you are in ketosis the high circulating free fatty acids do tend to inhibit insulin action so some carbs can be taken without causing a break out of ketosis but as to how much I don't think anyone knows for certain.

For me, I find it very hard to go without cups of tea. I can easily hold out until around 4pm on a fast day on nothing but cups of tea. I always allow around 80-100 calories of my 500 for the milk I have in that tea.

Will this have a negative effect then on the weight loss and other benefits I get from fasting?

I've tried green tea with lemon but just don't like it and don't think I can stomach black tea or coffee.

[carorees]

Witchy Wife, I'm sure it won't, or if it does the effect is so small to be unimportant in the general scheme of things...if you are losing weight you are massively improving your health anyway. And calorie restriction alone is good for health, so anything that helps you get through the fast day is fine (apart from high calorie food of course!).

Witchy Wife, I'm sure it won't, or if it does the effect is so small to be unimportant in the general scheme of things...if you are losing weight you are massively improving your health anyway. And calorie restriction alone is good for health, so anything that helps you get through the fast day is fine (apart from high calorie food of course!).

Thanks for your reply. I think I can happily follow this "diet" for life, but not if I had to cut out the cups of teas on fast days lol.

I always come in under 500 calories, so I don't have to worry about it. If I went over for one day, I still wouldn't worry about it.

I don't think that a 50 or 100 cals will make much difference. But the net calorie restriction will be less.

I'm guessing that rate of weight loss will be a linear relationship from the 500/600 cals up to TDEE. However, I do wonder whether there is a "catastrophe theory", non-linear relationship (a threshold level if you like)? You know, like applying a load to a beam in Engineering, OK, OK, OK, BOOM! (fail). Perhaps this may also apply to weight loss?

They say that you can have 1000-2000 cals worth of stored glycogen, so that gets used first, then when you eat again it is replenished. So unless you go carb free or skip breakfast and lunch you won't be starting to burn fat until well into the fast, if at all. I strongly suspect that the headaches people get coincide with a failure to switch to fat burning when the glycogen runs low. So I don't know if we can even talk about breaking the fast in the way you mean (i.e. out of ketosis) for most of the time we are fasting. It all depends on how big your glycogen stores are.

That is interesting. I sometimes have a headache the morning after a fast. I have blamed dehydration, which may be another culprit, but yesterday I started drinking fizzy water on fast days so I know I had over 2 litres.

Is it ketosis any time you are burning fat? Or is ketosis an advanced stage of fat burning you go into after a prolonged fast? The first few weeks might be water or glycogen, but if you keep dropping weight (as long as its not muscle ) I would imagine you must be losing/burning fat.

If you are continuing to lose weight on a 5:2 diet, then eating again can't be providing your TDEE and replenishing all the liver's glycogen. So at what stage of the cycle do we burn fat, or is that another we don't really know yet?

I am afraid I am full of questions.

D_C

"Nutritional ketosis" is when the circulating levels of ketones are elevated in order to supply the brain with an alternative to glucose, in the absence of sufficient of the latter. This normally takes over a day of fasting, if the "normal" diet is high in carbohydrates.

We burn fat all the time at rest and light/moderate activity levels.

[carorees]

The balance of fat and glycogen that is being used at any particular time is subject to so many variables that one can't really say. Your glycogen reserves (depends on the size of your liver and muscles and how long since you ate and what the composition of the food was), how much energy your body needs, the intensity of exercise, and whether you are fat adapted will all influence the balance of fat and glycogen burned.

I think you're right that we don't necessarily manage to replenish glycogen stores between fasts and that might explain why some fast days are harder than others.

You have good questions but there are no definitive answers!

Thanks for the info, I love learning about this sort of stuff - even if the answer is we don't know yet D_C