The FastDay Forum

Hi,
I've read through the various 16:8 threads, but I have a question that I haven't come across an answer too (or I have missed along the line). Does anyone worry about lowering their metabolism on 16:8, if for instance, they are sticking to around 1200 calories per eating window? Once upon a time I plateaued big time on a regular calorie restriction diet - basically maintained on 1200 and couldn't lose. So I'm wondering whether it would be advantageous to add in a higher calorie day each week to help keep my metabolism up?

I started on 5:2, but as usual I struggled big time to keep my calories down, and 16:8 feels easier for me.

why would you stick to 1200 calories in an eating window??? That's not part of it. The idea is you're supposed to eat normally - which means about to your TDEE.

You know that with 5:2, you're only restricting calories for two days a week, right? The other five days a week you're supposed to eat to around your TDEE. One of the advantages of this is that you don't lower your metabolism.

Have you tried doing it properly, without additional calorie restriction? Or did you immediately just try major calorie restriction five days plus fasting two days?

Sorry if I was unclear. My 5:2 was 2-3 attempts (one week I did three) of 500, and the rest of the days at least my TDEE, sometimes over.
I'm talking about calorie intake for 16:8 alone, not 16:8 + 5:2.

Hi Oxnard,

I do 16/8 every day and NEVER count calories. I have had enough of calorie counting to last me a lifetime which is why I don't so 6:1 for maintenance. I eat whatever I want and eat as much as I want but my appetite has reduced naturally as a result of the fasting so I am assuming I don't overeat but, I bet I consume a lot more than 1200 a day. The idea of intermittent fasting, for me, is to make weight management easier and more pleasant otherwise I might as well be back at WW.

Good luck,

Ballerina x

Thanks Ballerina.
I'd like to not count calories in the window...but am unsure whether I should or not. Since I still have anout 8kg to lose, and I imagine that any weight loss on 16:8 comes from a decrease in calorie intake. But if I were on maintenance I'd definitely have a go at not counting.

Hi:

I hear so much about 'metabolism'. Pills are supposed to speed it up. If you eat certain foods it will speed up. Eating several times a day is supposed to do it. I read if you drink six glasses of cold water each day you speed it up by a whopping 50 calories of usage. Building muscle is supposed to increase it. Fat people tell me they have slow ones.

While metabolism exists, I have always viewed TDEE as a proxy for it. You will generally find your TDEE slows down as you lose weight. Many people here post that as they lose weight, they lose weight more slowly than when they started. A short 45 year old woman weighing under 100 pounds can have a TDEE of under 1400.

I have seen no evidence that fasting slows metabolism (reduces TDEE all by itself). People that do long term fasts do not lose weight slower than those following IF - they lose weight faster. They do not hit a 'starvation response' or whatever, and stop losing weight or lose weight more slowly, they just keep losing weight at the same rate until they eat something, or they die of starvation.

Thin people have slower metabolisms than fat people, generally speaking (always exceptions). I know athletes that have TDEEs much lower than mine. I have to run 18 miles to burn 3500 calories, but they don't burn that many running a marathon.

So I would not worry about 'keeping your metabolism up'. It is what it is, and will probably fall as you lose weight. 16:8 is just skipping breakfast (and not making up for it by eating more later in the day). You can easily gain weight on 16:8 if you don't watch how much you eat in the 8 hour period. But you won't be gaining because of a slow metabolism, you will gain because of too many calories consumed.

Good Luck!

PS: If you want to see metabolism at work, watch this 'Why are Thin People not Fat' BBC video: http://topdocumentaryfilms.com/why-are- ... e-not-fat/ It may answer some of your questions, or bring up new ones!

There is evidence that dieting in general causes your metabolism to decrease beyond just what is caused by having a lower weight. Part (though perhaps not all) of this is thought to be due to loss of muscle, which is more metabolically active than fat. This is one reason why losing mostly fat is better than losing a mix of muscle and fat when you're on a diet. [supposedly IF causes less muscle loss than CR, and I've also heard that about low carb/Atkins]

I've linked to this before, but here it is again: http://www.nytimes.com/2012/01/01/magaz ... d=all&_r=0

I know a lot of people here are convinced by Salis' "famine reaction" or whatever she calls it, but I don't think all scientists are convinced by this.

I think people talk about metabolism a lot without really knowing that it has been affected. Though… perhaps they just have different ways of describing the same phenomenon (i.e., maybe "famine reaction", "starvation mode", and this extra lowering of TDEE I mentioned above are essentially the same thing). I'm sure I read on Mark's Daily Apple or some such site recently that he's not convinced unless they've actually had hormone levels tested.

While I mostly agree with what simcoeluv has said, I am hoping that by replacing some fat with muscle, I don't fall into the trap of a low metabolism that some dieters experience. Even after losing so much weight --unfortunately I didn't do body fat % measurements at the beginning of my IF journey, so I don't know how much of that was fat -- my body fat % is too high. I'm getting a more accurate measure of that soon, hopefully, but in the meantime, I'm doing resistance training to try to make more muscle.

Sorry… this had nothing to do with 16:8, but I thought it was worth commenting further on metabolism.