The FastDay Forum

"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)"

Depends what "Predicted" means. e.g Prospectively on 30/10 for November based on previous history, or retrospectively on 01/12 based on entered data (which may not be accurate)?

But looking at the data

4 - 2.8 = 1.2 Kg
3 - 2.1 = 0.9 Kg
4 - 2.5 = 1.5 Kg
3.75 - 1.6 = 2.15 Kg

Could not a significant part of these variances be just water retention type issues? Leaving relatively small calorific differences that can easily be accounted for by variances in activity (including both 'formal' exercise and other activity).

Perhaps there's a general issue of "limits" and measurement "accuracy"?
e.g If I weighed myself and the scales say it's 240 lbs should this be expressed as 240 +- 0.1 lbs (the scale) but due to the water retention effect we should be quoting 240 +- 2 lbs (so anywhere really between 238 and 242 'really' ), so only when it drops down to 237 is any loss really significant etc etc etc .

Hi PhilT,

"Water is a zero energy FFM component which can mess things up."

Temperature of water drunk may be significant in that:

"...Let's figure out exactly what you're burning when you drink a 16-ounce (0.5 liter) glass of ice water:

* The temperature of ice water can be estimated at zero degrees Celsius.
* Body temperature can be estimated at 37 degrees Celsius.
* It takes 1 calorie to raise 1 gram of water 1 degree Celsius.
* There are 473.18 grams in 16 fluid ounces of water.

So in the case of a 16-ounce glass of ice water, your body must raise the temperature of 473.18 grams of water from zero to 37 degrees C. In doing so, your body burns 17,508 calories. But that's calories with a little "c." Your body only burns 17.5 Calories...."

So folks drinking a lot of cold, ice water daily over the course of a month would get a calorie deficit of 4 x 17.5 x 31 = 2170 cals.

Similarly, perhaps those drinking mostly tea/coffee reduce their energy expenditure (since the hot drinks provide calorific heat)....

Then there's the difference between the two approaches to consider...

Talking of environmental factors, here's an interesting article in the Telegraph: "Losing weight could be as easy as turning down the thermostat"

http://www.telegraph.co.uk/health/healthnews/8281442/Losing-weight-could-be-as-easy-as-turning-down-the-thermostat.html

Temperature of water drunk may be significant in that:

"...Let's figure out exactly what you're burning when you drink a 16-ounce (0.5 liter) glass of ice water:

* The temperature of ice water can be estimated at zero degrees Celsius.
* Body temperature can be estimated at 37 degrees Celsius.
* It takes 1 calorie to raise 1 gram of water 1 degree Celsius.

Units fail. The calorie we use informally in dieting is actually the Calorie (large C, large calorie) or kg-calorie.

So it actually requires 0.001 calories to raise 1 gram of water 1 degree Celsius.

Drinking a litre a day for a month and raising it from say 8 to 38 C requires (38-8) * 1 * 30 = 900 calories per month.

[carorees]

Um, not quite sure where you're coming from here. If you think about water retention surely that cannot apply on a month on month basis? Using Occam's razor, I'd say the TDEE calculations are out!

By predicted loss I meant the app's estimation of calories burned vs calories eaten. As we know people tend to underestimate calories eaten the must likely explanation is the calories burned is under estimated. I have entered my exercise and some NEAT (i.e. Shopping, housework).

I think it is not water losses (I'll be a prune at this rate) or excessive muscle loss. I think it is more likely a greater muscle M&A than estimated for my height and weight in the TDEE calculator.

Mind you re Last Chance's post, our house is freezing!

Anyway, getting back to the non-responders, I still think it worth investigating. I was just answering a post from a last who says her TDEE is over 2100 but she thinks she is eating around 800 cals on feed days but no weight loss. Clearly there is something wrong there! Is she massively under estimating her food or is the TDEE way out?

Hi Caroline,

"If you think about water retention surely that cannot apply on a month on month basis? "

Yes, it applies to a single measurement. The problem you have here is that the monthly changes are not that great really and not too far removed from the intrinsic measurement variances and just one of which has been discussed at length here is "water retention".... So if you measure yourself and it's +-2lbs then how significant are changes of little more than this?

Anyway, getting back to the non-responders, I still think it worth investigating. I was just answering a post from a last who says her TDEE is over 2100 but she thinks she is eating around 800 cals on feed days but no weight loss. Clearly there is something wrong there! Is she massively under estimating her food or is the TDEE way out?

So she eats 800 * 5 and 500 * 2 ?

I've only ever seen reported BMR values below 1000 for chronic anorexics, while her TDEE of 2100 might be way out I don't think it's going to be as low as 800.

Watching "Secret Eaters" or similar I remember one lady who didn't count fruit calories, so am tempted to ask "are we sure" about the intake.

One conundrum I have no answer to is that of insulin resistance and inhibited lipolysis - if someone has high circulating insulin levels can that inhibit release of fat from adipose tissue ? if so, what happens to the energy balance / metabolism.

Yes, it applies to a single measurement. The problem you have here is that the monthly changes are not that great really and not too far removed from the intrinsic measurement variances and just one of which has been discussed at length here is "water retention".... So if you measure yourself and it's +-2lbs then how significant are changes of little more than this?

Over 4 months would we not expect more random variations or symmetry though - all of the actual losses were higher than predicted rather than appearing to be +/- x% of predicted.

4 months of extra water weight loss might be possible but seems a bit unlikely.

[carorees]

4 months of extra water weight loss might be possible but seems a bit unlikely.

That's what I thought! Just checked in the mirror...no, no more prune like than before I started!

"Over 4 months would we not expect more random variations or symmetry though - all of the actual losses were higher than predicted rather than appearing to be +/- x% of predicted"

Agreed. All losses are positive and this as a pattern is very significant. But 1 or 2 kg variance each month would seem to be close to a single known variant and within overall experimental error (bearing in mind all the other parameters).

"That's what I thought! Just checked in the mirror...no, no more prune like than before I started!"

The point is that the monthly changes seem to be marginal when compared to the known variances of a single weigh-in....

So for the software to have a prediction close within experimental limits to your actual values seems pretty good (or perhaps try "DietPower")....

Caroline

Two people may have a similar TDEE and, for example, be of similar age, activity levels and weight, but that doesn't mean they are both eating at TDEE. The problem is that it appears very few here actually count calories therefore it seems to me the big variable of calorie input cannot be reliably assessed.

The theory is "calories in = calories out" which I don't think can be disputed. Supposedly one lb of weight loss requires a calorie deficit of 3,500 which I think has been queried but only for those who are already lean; for those of us who are overweight the 3,500 figure still probably applies. A quick, rough check using your basic data indicates that, if your TDEE conforms to the average for a sedentary middle-aged female then you could only have achieved 1.5 lb/week weight loss by eating about 450 cals a day below your TDEE. If you're convinced you've eaten at your TDEE level throughout the weight loss then you're an outlier. As I'm sure you're aware, every set of data such as TDEE's etc must have outliers.

Not very well written but no time to edit. Anecdotally, the only other time I dieted I calorie counted and kept an exercise diary; my analysis showed that I was about average in terms of TDEE, calories in/calories out, etc etc.

Ken

Maybe the calories in/calories out theory isnt correct.
http://www.second-opinions.co.uk/do-cal ... Tzgilft8Rk

From the Progress tracker data for Males on 5:2 (any age or time). The starting BMI seems predictive of the rate of loss (lbs/week). The higher the initial BMI, the greater the median loss per week across the group.

Starting BMI, Median Loss Values (lbs/week)
=======================================
Healthy, 0.37
Overweight, 1.45
Obese, 1.56
Morbidly obese, 4.2*

* Not many samples, and not for long...
Interesting to see how this evolves as more data is added.

That would make sense though as a % of bodyweight would probably be similar.

[carorees]

So, getting back on track...do people think it is worth doing a survey of the top and bottom quartiles of weight loss? Even if the top losers are very overweight young chaps who do lots of exercise and the bottom are sedentary middle aged women with just a little weight to lose, surely if we stratify the population by gender and BMI we could get some interesting info.

So my suggestion is first to stratify and then take the top and bottom quartiles of each population and either obtain data prospectively by asking them to continue 5:2 in exactly the same way as before and then answer a questionnaire or retrospectively by just sending out the questionnaire. We could ask for volunteers or ask Moogie if the progress tracker data could be used to identify members by applying the relevant filters and then extracting the top and bottom quartiles who we could send the questionnaire to (keeping the data anonymised).

If you all think its a waste of time, I'll stop banging this drum!