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General 5:2 and Fasting Chat

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A common question on this Forum is 'Why don't I lose weight?', followed by 'Why do I lose weight so slowly?' Enter TDEE

When I started roaming around this Forum, I kept running into the term TDEE. People used it quite a bit, and it seemed to have some relevance. I finally found Carorees 'Forum wiki' post, that defines many of the terms used on the site, including TDEE (thank you Carorees!). (see viewtopic.php?f=1&t=1133)

Quoting - "TDEE = total daily energy expenditure (how many calories you burn in one day and so how much you would need to eat to maintain your weight)".

Then I ran into the Progress Tracker, and it seemed to compute my TDEE for me. Being curious, I also looked for similar calculators on the web, and found several (a good one - http://www.mayoclinic.com/health/calori ... or/NU00598). Strangely, several gave me TDEE numbers quite different than that of the Progress Tracker - usually quite a bit higher. The variations seemed to center around my chosen activity level.

To determine my TDEE, I decided it better to guess at my correct activity level, and then choose the activity level one level below that (if possible). My reasoning was as follows.

First, TDEE is, after all, an estimate. So we are not talking precision here. Second, I know I usually overestimate how much activity I do over any given period of time. And third, I figured that if by underestimating I turned out actually to be right, my estimated weight loss would fall in line with reality (more on this later), but if I was wrong, I would lose more than expected and be much happier for exceeding my weight loss expectations. In effect, I would gain happiness by underestimating my activity level. And I am all for being happy!

So, how does TDEE help explain how 5:2 works?

Let us say you are a female with a TDEE of 2000 calories per day (about average, but everyone's is different) and are starting 5:2. Here is how you can compute your expected weight loss.

For two days a week, you will eat only 500 calories, thus cutting 3000 calories out of your diet for the week (2000 - 500 = 1500 calories cut in each of two days). As there are around 3500 calories in a pound, you might expect to lose about 14 ounces for the week (3000 cut from diet divided by 3500 in a pound times 16 ounces in a pound equals 14 ounces, rounded). These numbers tend to explain a lot.

First, they explain why the average weight loss is around a pound a week under 5:2.

Second, they explain why men lose faster than women - because on average a man's TDEE is 2400 calories per day (men often are bigger). So when they eat 600, they are cutting out 1800 calories from their diet and thus losing more each week than a woman cutting out 1500 calories.

Third, they explain why so many people following 5:2 try to speed things up. 14 ounces a week is pretty slow. Several typical attempts to speed things up include going to 4:3 (adding another fast day and deleting another 1500 calories from the week - this adds an additional 7 ounces of loss for the week), or not eating any calories on fast days (liquid fasting) - this cuts 1000 additional calories out, or produces a 5 ounce additional loss. Some people try to increase their calorie usage by exercising (trying to increase their TDEE). And, if they walk 25 miles each week, they will indeed burn an additional 3500 calories, thus upping their weekly loss to 30 ounces.

(As an aside, if you are really in a hurry you can simply not eat for a week, something this Forum rightfully shuns. But if you run the numbers, at most you will cut 14,000 cal. out of your diet, or 4 pounds worth - lest you really think you lost 4 or more pounds of fat weight after your first week of 5:2.)

Now, all of the above assumes that on your five feast days, you are eating 2000 calories per day on average. If you are eating more than your TDEE on average each week, your weight loss will be less than expected. If you are eating less, your weight loss will be more. This explains why many people doing 5:2 experiment with dieting on top of the 5:2 way of eating as a way of speeding up their weight loss (ie. follow the Atkins diet on their 5 feast days). This also explains why people that think 5:2 means you fast for two days and then can eat as much of whatever you want for the remaining 5 are usually quite unhappy and complain they are not losing weight.

Finally, all of these antiseptic numbers work with the background of normal fluid retention and dehydration in the body, either of which can overwhelm (or artificially supplement) any weight loss that is measured in ounces per week.

So, there we have it, TDEE in an (unscientific) nutshell. I guess all I can say is if you are having the results you want, ignore TDEE. If not, accurately determine your TDEE, insure your fast day calories do not exceed 5/600 and count calories on feast days to see if they average your TDEE or below. That will probably identify the problem. Otherwise

BE PATIENT!

It really does work over time. :smile:
Brilliant thank you, I think you've just answered several of my questions.
simcoeluv, I love your posts :) You always hit the nail on the head and you say it in plain English. Gonna sticky this one for you!
simcoeluv wrote: A common question on this Forum is 'Why don't I lose weight?', followed by 'Why do I lose weight so slowly?' Enter TDEE


Second, they explain why men lose faster than women - because on average a man's TDEE is 2400 calories per day (men often are bigger). So when they eat 600, they are cutting out 1800 calories from their diet and thus losing more each week than a woman cutting out 1500 calories.



BE PATIENT!

It really does work over time. :smile:


agree re all your points but the "men lose faster than women" doesnt apply in this household. which leads me to a new thread... stand by
spot on, now where did I put my patience lol!
cal wrote: spot on, now where did I put my patience lol!


Hear, hear! Haha :)

Wonderful post, simcoeluv. It's nice to have it all there in plain English, as it's good to be reminded! I'm a 5'3" woman with under a stone to lose so my weight loss has been fairly slow, but that is also because I didn't realise my TDEE was so low! Only around 1600 for me at the moment, so I aim for 1400 on my feed days and 500cal on my fast days. Weight started coming off steadily.

I do have to give a shout out to those who are impatient like me, though, there is a bonus to losing weight slowly! It comes back on much more slowly as well :) I was off 5:2 for a month and was eating lots of bread, sugar, fat, wine, etc. and only put on a pound or two, which I lost as soon as I started fasting again. I didn't believe this when I was told but now I have experienced it! Very comforting :)
Brilliant, thanks for the very clear explanation!
Wow thanks for that simcoeluv :like: that should explain to everyone how it's done :clover: Sue
Hi everybody
sorry to jump on the bandwagon ;-) but i have a question about weight loss whilst on the 5.2, i started just a little over 2 weeks ago and done 4 fasts so far, i exercise regularly too and eat healthy most the other days lol, so am wondering, when does the weight start to come off? after the fisrt week, second? because even though i hadnt weighed myself for well over 2 years i did this morning and i havent lost anything! i dont want a major weight loss, maybe 1 stone will be enough for me,( i am a size 10,7 years ago i was a 16) doing this mainly for the health benefits, i know i am loosing inches because of the way my clothes fit etc... anyway sorry for the rant! just would like some input on this, much appreciated and thank you for reading!!!!!!!
good luck fast buddies xx
Angie
Hi:

I did not lose any weight for the first two weeks: 5-2-diet-chat-f6/topic6491.html

One issue might be that you may weigh the same as you did two years ago, but not the same as you weighed two weeks ago.

:clover:
Hi Simcoeluv

Thank you for reply, i didnt think about that, i guess we all get a little impatient at times!
But i am going to stick with it, and hopefully i'll see some changes soon lol!

Angie
I was thinking about this post - it's correct, of course. But there are other factors not covered. So while it's a great rule, unfortunately there are also exceptions.

For me, I have a messed-up thyroid. It's technically too fast, which should mean I lose weight effortlessly and eating what I like. Except for the fact that I'm medicated to bring my thryoid down to a normal level - so the numbers above should work correctly. But my thryoid has not been remaining constant, and my medication has needed adjustment several times this year since starting 5:2. When my thyroid levels in my blood are higher, the weight comes off as it's supposed to. When they dip, I'm fighting to not gain weight by looking at food. So there's one factor in play.

Another is the variability of one's metabolism from other factors. Some people swear by simply lowering their calories on a daily basis they lose weight, where others find they have to have highs and lows in their calorie intake or their metabolism "goes into starvation mode" and weight loss slows down. Some people find that exercise helps the fat melt away easily whereas others say it just makes them want to eat a lot more. Dr. M did another BBC show on exercise where was genetically tested and shown to be a "non-responder" to aerobic exercise. Bummer!

I just don't want anyone to read this and think "but I'm being good - why am I not losing my 14 ounces per week?!?!?!"
There could be other factors such as hormones, how much salt is in the diet. IF you eat a lot of processed foods, salt will cause a lot of water retention.
Taste testing a lot of food, if you are a cook or a baker, can add up. And there could be hidden calories that you are not aware of.
I guess it means lots of patience and perseverance.
14 ounces a week is pretty slow.

In my opinion that is incredibly fast. The dieters of the mainstream forums can only dream of such a steady weight loss over a long time.

Calorie deficit per fast day for 1:6, 5:2 and 4:3:

3/4 = 0.75 = 75 %

Calorie deficit per week:

6:1

1 x 0.75 / 7 days x 100 = 10.71 %

5:2

2 x 0.75 / 7 x 100 = 21.43 %

4:3

3 x 0.75 / 7 x 100 = 32.14 %

5:2 is popular because of the fine balance between speed and comfort. I still believe that 4:3 works in the same way as 5:2 because a weekly calorie deficit of 30 % is generally considered as the upper limit of reasonable weight loss.

Calculated weight loss per week:

(Calorie deficit per week) / 7000 [for kg] or 3500 [for lb]

Duration of the diet in days:

7000 [for kg] or 3500 [for lb] x (intended weight loss) / (daily calorie deficit)

If we realize that two pounds don't equal one kilogram it is clear that the numbers 3500 and 7000 are only very rough equivalents. A higher value (→ less fat loss) may be more realistic because fat loss is often accompanied by muscle loss.
http://www.zoeharcombe.com/the-knowledg ... -calories/

Some people try to increase their calorie usage by exercising (trying to increase their TDEE). And, if they walk 25 miles each week, they will indeed burn an additional 3500 calories, thus upping their weekly loss to 30 ounces.

The TDEE of the weight tracker on this website includes all sportive activities and doesn't use that calorie deficit for weight loss purposes. So it doesn't matter how many hours you exercise per week – you always get the same number for the remaining time until you reach your target weight. That is a good choice because weight loss, sports and health are different topics, and especially 4:3 dieters should not try to create additional calorie deficits, whereas 6:1 and 5:2 dieters can safely exploit an additional calorie deficit by 10 or 20 % for their weight loss.

For me x:y means creating a calorie deficit of z % on y days of the week by counting calories on y days only.
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