The FastDay Forum

This great dataset being provided here, and Moogie's excellent charts, are throwing up some interesting questions. I am puzzled by the age-related results:



Why do the young lose so much more weight than the old? The data appears substantial, consistent and credible, but I have never before heard of it being easier for the young to lose weight, nor that it gets steadily harder as you get older?

[carorees]

You know you have to put your age into the TDEE calculators? Is that because BMR decreases with age? Could be the answer. Can't look it up at the moment...

[Tracieknits]

Anecdotally, people remark their metabolism seems to slow as they get older, pounds seem harder to shed and/or they don't need to eat as much as when they were younger.

Perhaps that's actually true and the effect is seen with this chart?

Anecdotally, people remark their metabolism seems to slow as they get older, pounds seem harder to shed and/or they don't need to eat as much as when they were younger.

Perhaps that's actually true and the effect is seen with this chart?

That's the way I've always understood it,eventually you only have to look at a cream bun and you put weight on

Well that has been true for me. I would say there is an activity element to the answer. No matter how much we try to avoid it, I think it's just life that as we get older we start to move more slowly and less often and less frequently. This may not seem like much, but my guess is it has a greater effect on our calorie burning than we'd like to think. Another thing the Horizon programme highlighted was how just not sitting down can affect health and weight. Most 20 year olds by nature spend more time on their feet moving than say 50 year olds. They probably also move faster. I'm saying "most" and applying that to all age groups because of course there are always exceptions. And when hip or knee or other problems start to bother us in middle age that has a slowing effect and can't be helped really. That's just life and can in fact be the result of a very active lifestyle up to then.

I should have read that back properly shouldn't I. I meant less often and with less intensity. Less often and less frequently are the same thing. Durh!

Thanks for the replies. Seems you are right Caroline: http://www.bmi-calculator.net/bmr-calculator/. Yes I guess slowing metabolism and less physical activity must be the cause, but I am still surprised the figures are so dramatic.

By the way Gum168, you can edit earlier posts here, I often find I wrote something meaningless and then fix it afterwards.

People generally become less active as they get older too.
When you're young you've got bags of energy generally. A lot of younger people don't have cars either.

I noticed a couple of things on the progress tracker page that raise a few questions, regarding the data and calculations...

Copied from the Progress Tracker page using the filter:

18-25
"3 of whom have lost a total of 10.96lbs over a combined total of 3 weeks and 4 days.
This equates to an average of 3.07lbs or median of 2.99lbs lost per member per week..."

i) They are just starting out and weight losses are high at the beginning.

ii) (10.96/3)/3 = 1.21 lbs per person per week on average or there abouts and not 3lbs. But it would look to be about 3 lbs lost for all the 3 members in this group per week

46-60
"102 of whom have lost a total of 744.24lbs over a combined total of 490 weeks and 3 days.
This equates to an average of 1.53lbs or median of 1.23lbs lost per member per week..."

i) They have been at it a long time (and may have periods when they gave up).

ii) (744.24 / 490) / 102 = 0.014lbs per person per week on average


or

iii) Perhaps there's scope to refine the calculations (OK bugs present)?

iv) or perhaps I'm not understanding something???

I think it's something to do with muscle mass which peaks at about age 25 and decreases steadily from about age 30 onwards. The greater muscle mass a person has the more calories their body burns because muscle is metabolically active whereas fat isn't. So as we age we lose muscle and our metabolism becomes slower so we don't need as many calories. This is also why men often lose weight quicker than women as they generally have a higher muscle to fat ratio. It's bit of a bummer for us gals over 30, eh?

Oh. So 50 something isn't so good at all.

It's not necessarily to do with lack of exercise. I exercise far more frequently now in my sixties than I have ever done in my life. Something happens when women hit the menopause and it ain't good. The week before last when we had the snow and ice I skipped all my exercise classes though I still fasted two days. Result? I put on 2lbs. Basically you go into old age a pin or a cushion, the saying goes. My sister is a pin and I would be the cushion had I not watched my weight from being about twenty. That's why this way of life is so good for me. I've gone through life denying myself food, or eating what other people call "normally" and putting on weight. Now I'm happy with my weight as long as I fast two days a week but I must still keep up the exercise or it will pile on.

[Moogie]

I noticed a couple of things on the progress tracker page that raise a few questions, regarding the data and calculations...

Copied from the Progress Tracker page using the filter:

18-25
"3 of whom have lost a total of 10.96lbs over a combined total of 3 weeks and 4 days.
This equates to an average of 3.07lbs or median of 2.99lbs lost per member per week..."

i) They are just starting out and weight losses are high at the beginning.

ii) (10.96/3)/3 = 1.21 lbs per person per week on average or there abouts and not 3lbs. But it would look to be about 3 lbs lost for all the 3 members in this group per week

46-60
"102 of whom have lost a total of 744.24lbs over a combined total of 490 weeks and 3 days.
This equates to an average of 1.53lbs or median of 1.23lbs lost per member per week..."

i) They have been at it a long time (and may have periods when they gave up).

ii) (744.24 / 490) / 102 = 0.014lbs per person per week on average


or

iii) Perhaps there's scope to refine the calculations (OK bugs present)?

iv) or perhaps I'm not understanding something???

I think you may be misunderstanding something. That or my maths is completely wrong - although the numbers are totally backed up by the behind the scenes calculations which I had Dominic (our resident stats nut) check over!

As I understand it there is no need to divide by the number of members after their total loss has been divided by their total time spent on the diet.

Look at it this way with your first example of the 18-25 year olds who had been dieting for a combined total of around 3 weeks. With only 3 of them in the equation that works out that they have each been doing the diet for around 1 week each (okay 1 week 1.3 days). So the loss is correct as calculated, around 3lb a week for each user. There's no need to divide again by the number of users.

Similarly if you want to boil down the numbers on the other example you gave, 490 weeks divided by 102 users is an average of 4.8 weeks on the diet per user. The average weight loss over their diet timespan would be 744.24/102 which is 7.29lbs. If they have lost 7.29lbs over 4.8 weeks that's about 1.52lbs lost per member per week.

I can't see where the figures are wrong? I think you've misunderstood something along the lines.

If the stones/lbs figures are fractionally out it is only because all the calculations are done in kg and each individual result is then converted to lbs and rounded as needed. So, there may be a hundredth or a thousdandth inaccuracy in the conversion to lbs.


Will someone please correct me if I'm wrong here? Dominic?!
I'm on a fast day so am beginning to question my mathematical abilities but am pretty damn sure it's being calculated correctly!

Hi Moogie,

Look at it the issue the other way and taking the simplest 18-25 case (again!)....

"2.99lbs lost per member per week..."

Lets call this 3 lbs 'per member per week' ....(1)

"3 members"

So 3 x 3 = 9lbs for 3 members per week ....(2)

"3 weeks"

9 x 3 = 27 lbs ....(3)

So the anticipated weight loss for the group of 3 for 3 weeks at 3lbs a week is 27lbs

QED...

or I've lost my marbles

Sorry

[Moogie]

The 3 weeks is a combined total between all 3 users, it is not that they have each been doing it for 3 weeks.

So, if each member has been doing it for about a week (3 members, combined total 3 weeks), then 3lbs aweek is correct.
3 members x (average) 1 week each x 3lbs = 9lbs
(now bear in mind that it's actually 8.33 days each on average, and a little over 3lb using the mean rather than median and that should take us up to the 10-11lb mark)