The FastDay Forum

[carorees]

I think you have to include same muscle mass in that boboff as the muscle makes a huge difference to BMR. And if you do that, the woman will then weigh more due to higher fat %. Then you have to consider different BAT levels between men and women too.

It's all v complicated!

Hi all,

Just a thought, instead of going into all the tech stuff behind the differences in losses, why not set out some base lifestyle / Habit questions,

Do you eat your full calories on fast days?
Do you count calories on feast days?
Do you exercise / How much?
Do you still binge on feast days?

I am sure there are a lot more relevant questions you can think of but this may show a pattern within the subsets and make it a lot easier for the people not doing so well to identify the differences and make changes.

[carorees]

The problem with the simple mathematical view is that we don't have accurate figures to plug into the formula. The maths is right but our information is inaccurate!

For example, as I track calories and exercise on fat secret, I was able to look at the predicted versus actual weight loss I achieved over the 4 months:
November: predicted loss, 2.8 kg; actual, 4.0 (ratio P:O = 1.43)
December: predicted, 2.1; actual, 3.0 (ratio 1.43)
January: predicted, 2.5; actual, 4.0 (ratio 1.6)
February: predicted, 1.6; actual, 3.75 (ratio 2.3)

So you can see that even applying a correction factor of say 1.43 would not accurately predict the observed weight loss.

So what is the source of the variation? That is what we are trying to find out!

There may be a difference between creating your calorie deficit by cutting down by a bit every day or by cutting down massively on two days and not on the others. In February I overate hugely on weekend away which lowered the expected loss but not the observed loss. The first fasts after the weekend away produced a large decrease in weight, which persisted for more than is likely to have been due to water changes (the second week after the blow out also gave a big weight drop).

Personally I do not believe a man and a woman, with the same height, weight and exercise would loose weight any differently if eating the same foods.

I do, because in most cases* the woman would have a higher fat % and a lower RMR than the man.

* Comedy lesbians from Central Casting excluded

[carorees]

Yes I think we have to recruit volunteers who are willing to count calories for a month! If we can't get enough participants I guess we have to wait until we have more members.

This sounds so interesting, and really could assist so many with tweaking the plan to best suit them. So, if you did a month trial and asked participants to keep track of intake even on the feast days, I wonder if it would not best serve to only ask those who are already keeping track, as I am sure that the act of keeping track (Paying attention, observing) would have an impact(change)intake. This being said, seems that if they were consistent through the whole month, it wouldn't matter. Unless, it were a big enough change from the caloric intake prior that is causes the up/down phenomena that people describe when initializing the plan or changing things up. Just a thought.

[carorees]

No that's a good thought. Hmm, it would be interesting to know whether keeping track has a big impact. It doesn't feel like it but that means nothing! I suppose that would be another investigation.

[carorees]

There's a long debate on protein intake and muscle preservation but if you look at the studies on intermittent fasting quoted in that thread you will see that fasting results in preferentially losing fat with only small losses in FFM so your predictions about 25% muscle loss are not applicable to this WOE. It is likely due to the big increases in growth hormone during fasting.

However, we're getting a bit OT here! I presume you're suggesting it's not worth doing the survey/stats? The thing is that we can't know our exact TDEE or even exactly what calories we extract from food, nor how much protein sparing is going on. We can only look at the TDEE calculated by the various online calculators, what we are eating and what exercise. It may be that we find no common factors among big losers that are missing in little losers (or should we say good responders vs poor responders) but even that will tell us something we can pass on to the members.

I think the correlation analysis is worthwhile. If someone comes to it fresh and it doesn't work then some evidence based suggestions would be helpful.

[carorees]

I think that there could be a lot of factors apart from exercise that might result in one person responding well while another apparently identical person with respect to gender, age, height, weight and exercise, does not.

It could be as simple as which TDEE calculator is used!

The psychological impact must not be underestimated, such that those reporting that they are reducing calories on feed days are actually failing to do that but are not reporting/aware of the fact. The appetite reduction after fasting could be a factor. There could well be a change in NEAT such that spontaneous movement is reduced in non-responders. The length of the fast might affect thyroid function which could be corrected more rapidly by eating well the next day rather than restricting calories on feed days. Substrate utilization could be a factor...perhaps the degree of ketosis is important. If the difference is indeed muscle loss we should look at waist measurements as well.

I think your comments about strength training are important so we should definitely include the type of exercise as well as the amount in the survey.

Hi Caroline,

This is an interesting debate.

"I am a middle aged and sedentary woman and yet my average weekly weight loss has been around 1.5 lb+ which is twice what some other middle aged sedentary women are achieving. What am I doing different from similar people who are not losing so fast?"

I thought you were doing HIIT at one point? If not doing it now, then perhaps your body FAT/Muscle percentages, cardio vascular fitness and BMR are not typical of truly "sedentary" women?

Generally, I have a simplistic view of the observed variances and I am not sure that there is indeed anything to study?

My simplistic views are that:

1. Feed days
i) Some folks (me included) are eating 'too much' on feed days.
ii) Some folks are calorie restricting on feed days.

2. Fast days
i) Some folks follow the 500 or 600 as prescribed.
ii) Some have 0 calories
iii) Some have failures on fast days.

3. Exercise
i) Some do none at all on either fast or feed days
ii) Some do lots throughout the week.
iii) Some do just cardio
iv) Some do just strengh
v) some do a mixture cardio and strength.
etc

4. Environmental Factors (affecting Calories burnt)
i) What temperature is your home or office? (will impact on calories burnt)
ii) Cold or hot drinks? e.g you may burn more calories drinking lots of water from the fridge rather than at room temperature or warmed.

etc etc

All these underlying variances, when compounded together in multiple combinations together with other factors such as scale accuracy and accurately calculating calories consumed will have a big bearing on the outcomes of the "5:2".

I do find the 4:3/5:2 issue particularly interesting, but only because I resorted to 4:3 to remain on-track at 1 or so lbs a week, but as I mentioned above, only because I simply eat too much on the feed days a couple of weeks ago and several since .

I've mentioned several times my concerns about the "Trans Penine Way" aspect of the 5:2 presentation in Dr Ms Horizon program, or the "TPW-diet" as I termed it. This lead him to the "Over a stone in 5-weeks" statement in the program (and which I believe has give many folks an over estimate of what may be achieved).

Perhaps a simple preliminary study of exercise levels and differences between the top and bottom quartiles would be the place to start? Perhaps not, since there's a big perception difference between "Formal Exercise" and "calorie burning Activity"?

Perhaps there's an element of "What's the difference between a duck?" about all of this....

[carorees]

I do do HIIT but apart from the 3x20 secs 3x per week I am sedentary! Hard to believe it could make much impact but perhaps it does!

My particular interest is in those who report that they are calorie restricting on feed days but not losing weight. I can think of a few reasons why this might be, for the most part down to inaccuracy in estimating TDEE and food/drink calories, but just possibly due to the factors I outlined above. It could well be that exercise and NEAT is the key.

It would be interesting to compare the calories eaten on feed days with TDEE calculated by different methods. I imagine body type might be important (mesomorph vs endomorph) add having a bigger muscle mass will make a difference even if you don't use the muscles formally! So we could add body type to the questionnaire.

I completely agree that the hype about a stone in 5 weeks has led many to be disappointed and the exercise MM took was conveniently overlooked. (I see in his recent article on the fast diet website that he mentions how he walks everywhere though).

However, aside from all this speculation you have the conundrum of why some don't lose weight. If you consider that most people were either maintaining their weight or gaining fairly slowly before they started on 5:2 then theoretically if they continue eating as they did previously on the feed days but add in two fast days then they should lose weight!

I have a suspicion that if you allow people to "eat what they like" you get three groups: those who were overeating only a little before and who on adding some fast days eat slightly less than they used to on feed days due to the appetite thing...they lose weight. Second some people have been dieting already and feel let off the hook so they increase their intake on feed days which with the reduced metabolism due to the previous weight loss means they are eating more than before and so they fail to lose weight. The third group can't believe it could work and try to cut calories on feed days too, some of these lose, others don't. This is the interesting group. Were they gaining weight so rapidly before starting the fasting that even cutting calories on feed days is not enough for them to lose weight? Or is there more involved?

Wasn't it one of MM's documentaries where they wired people up and found they underestimated calorie intake? Can't remember which one.

That was an eye-opener for me, as though I eat very well, it was too often and too much.

[carorees]

I suspect this is what is happening. In fact I saw a paper where they found the tendency to underestimate the amount eaten increases as more weight is lost and is one reason why people put weight back on as soon as they stop dieting.

As it's the difference between intake and expenditure we're considering it doesn't need a 40 to 130% increase in expenditure.

2000 - 1800 = 200, 2200 - 1800 = 400 for example. 10% more expenditure doubles the deficit.

Water is a zero energy FFM component which can mess things up. If a gram of glycogen is stored with 3 or 4 grams of water you can lose 4 kg for a deficit of 4000 calories whereas with pure fat loss 4000 calories is equivalent to one pound (less than 0.5 kg).