More Scientifically Accurate Weight Loss Projection

pwfkbf

I love MFP for calorie tracking and accountability, but I haven't found the weight loss prediction feature particularly accurate, especially over time. Has anyone else tried out updated calculators like this one [https://www.niddk.nih.gov/bwp] as a reality check about predicted weight loss (including inevitable plateaus)? Apparently, nutrition scientists now believe that the conventional, linear understanding of weight loss (500kcal/day reduction=1lb/week loss) is over-simplified because it doesn't account for early easy losses and eventual metabolic slow-down. I'll be interested to see which model proves more accurate over the coming year for me. I'd love to hear from anyone who tried this "new diet math"!

wunderkindking

I had to google to get a link that worked (this one says 'not found' on the nih website) and I don't know about the accuracy but it might have solved my "WTF IS MY MAINTENENCE" problem with their more precise activity modifiers (note: They use TDEE which includes exercise unlike MFP but still) which I appreciate.

That said I don't think anything is ever going to align perfectly. There's just too much variation in day to day routine movements, NEAT, types of exercise done, and all the things that influence scale weight beyond fat. The scale is often a massively lagging indicator of fat loss for me, anyway.

cmriverside

All online calculators use an algorithm that is basically based on the mean numbers across populations.


All of them are estimations.



To find your true weight loss with your calories and your tracking method and your activity and exercise level - you'll have to run the same experiment we all have to run.

Pick a number
Use it for 4-6 weeks
Adjust at the end of that time when you have good trending data to use


Go forward using your OWN data, not a population-wide extrapolation.



As an example, I eat a good 400-500 calories per day MORE than any calculator tells me I should be able to eat to Maintain my current weight. I use a digital food scale and have been logging my food for 14 years so I think I'm pretty close, accuracy-wise.

penguinmama87

This calculator is pretty similar to the results I have with MFP once I add my daily exercise. I was able to get the link to work by eliminating the bracket at the end of the URL. I do like that it gives me an estimation of my maintenance calories once I reach goal weight. The simulation though in expert mode seems to be a pretty straight drop day to day. I don't see any fluctuations there as you say in your OP. Am I missing something?

Lietchi

I tried to enter my data, but if find the activity level estimates and descriptions quite vague. I mean, what is 'light running' anyway? And so many types of exercise not even in the list, etc.

I agree that the weight prediction on MFP is useless, but this calculator is also presuming that we'll eat the same number of calories x days in a row and have similar activity levels x days in a row. That really isn't applicable in my case, I eat more on active days and less on inactive days, and my activity level varies regularly. I do like the blue band though, which (I presume) gives a range of expected losses depending on how statistically average we are.
I'm not sure where you think 'early losses' (water weight 'woosh' at the beginning of weight loss?) are incorporated in this model? As for 'metabolic slowdown': what do you mean by this concept? The model seems to lower caloric expenditure gradually, but it's not clear whether this is simply based on a smaller body burning less calories, or metabolic slowdown that might occur due to being in a deficit such as slower hair growth etc.?

I'm not sure this calculator is more accurate, I think it's more detailed (+margin for being metabolically average or not)

I find the calorie estimates my fitness tracker gives me (and which vary from day to day, just like my daily calorie intake!) much more interesting and useful, since I can track them against my actual weight loss and food intake to determine if they're accurate and that could also be useful for trying to predict future weight loss. I love my spreadsheet

pwfkbf

https://community.myfitnesspal.com/en/profile/usercard/1009553143, my understanding of the "new diet math" theory is that as we lose weight, the same exercise will burn fewer calories, and additionally, our bodies' thermodynamic response to weight loss is to launch responses to adjust our energy expenditures downward in order to maintain equilibrium. https://pubmed.ncbi.nlm.nih.gov/21872751/ . This researcher argues that these assumptions are not accounted for in older weight loss predictor models, and that as a result, the older models predict faster and more consistent weight loss over time. The research appears to have been undertaken to provide a more realistic long-view of predicted weight loss and, ultimately, of maintenance, so that people form more realistic expectations and understand that our bodies have counter-weight-loss reactions that might help some folks understand frustrating plateaus.

cmriverside

pwfkbf wrote: »

https://community.myfitnesspal.com/en/profile/usercard/1009553143, my understanding of the "new diet math" theory is that as we lose weight, the same exercise will burn fewer calories, and additionally, our bodies' thermodynamic response to weight loss is to launch responses to adjust our energy expenditures downward in order to maintain equilibrium. https://pubmed.ncbi.nlm.nih.gov/21872751/ . This researcher argues that these assumptions are not accounted for in older weight loss predictor models, and that as a result, the older models predict faster and more consistent weight loss over time. The research appears to have been undertaken to provide a more realistic long-view of predicted weight loss and, ultimately, of maintenance, so that people form more realistic expectations and understand that our bodies have counter-weight-loss reactions that might help some folks understand frustrating plateaus.

That's nothing new.


Less mass requires fewer calories to move that mass. As the body becomes smaller it takes fewer calories total to keep that body moving AND running its basic day-to-day functions.


As you lose weight on Myfitnesspal, you go into your Goals and update your current weight. It then adjusts downward the number of calories you are allotted to continue to lose weight. It's all accounted for.



In all, every online calculator is going to give you estimations of your calorie needs based on a population-wide algorithm. Nothing new under the sun.

Under-eating for long periods of time will cause down-regulation that is beyond what would be expected if not restricting calories. That's why it's good to take diet breaks when in a prolonged calorie deficit.

Metabolisms don't stay low. Eating at maintenance for a week will fix most metabolic slowing caused by prolonged calorie restriction.

Here:

https://community.myfitnesspal.com/en/discussion/1077746/starvation-mode-adaptive-thermogenesis-and-weight-loss/p1

and Refeeds:

https://community.myfitnesspal.com/en/discussion/10604863/of-refeeds-and-diet-breaks/p1

AnnPT77

You own results are your best guide, once you have at least 4-6 weeks of sound calorie logging and weight loss data.

For a multi-week recent time period, total the calories you've eaten.

Next, total the pounds you've lost over the same period (pounds and fractions, if your scale has fractions). Multiply that loss in pounds by 3500. That's the approximate number of calories of fat you've lost (subject to error from water fluctuations, blah, blah, blah - close enough).

Add the calories eaten and the calories from the pounds lost.

Divide by the number of days in the time period. That's your approximate real-world daily maintenance calories for that time period.

Subtract a sensible number for your calorie deficit (250 calories per day = about half a pound fat loss per week, on average, assuming compliance).

If your logging is reasonable accurate, that result is much more personalized/accurate than any so-called "calculator".

Repeat the math periodically, adjust intake if and when needed. It's worked fine for me for almost 6 years now (loss then maintenance), and the calculators tend to be howlingly far off, for me.

P.S. If you happen to be female & premenopausal, use whole menstrual cycles to do this math, i.e., compare body weights at the same relative point in at least 2 different full cycles.

lemurcat2

pwfkbf wrote: »

https://community.myfitnesspal.com/en/profile/usercard/1009553143, my understanding of the "new diet math" theory is that as we lose weight, the same exercise will burn fewer calories, and additionally, our bodies' thermodynamic response to weight loss is to launch responses to adjust our energy expenditures downward in order to maintain equilibrium. https://pubmed.ncbi.nlm.nih.gov/21872751/ . This researcher argues that these assumptions are not accounted for in older weight loss predictor models, and that as a result, the older models predict faster and more consistent weight loss over time. The research appears to have been undertaken to provide a more realistic long-view of predicted weight loss and, ultimately, of maintenance, so that people form more realistic expectations and understand that our bodies have counter-weight-loss reactions that might help some folks understand frustrating plateaus.

That would affect a prediction for how much you would lose in a year or 6 months, perhaps, but it shouldn't affect how much you lose on average in a month or the 5 weeks MFP predicts (that prediction is silly since people don't eat the same every day). Also, like Ann says, people vary some and sometimes make mistakes regarding activity level or exercise burns, so adjusting for actual results would always be sensible.

ninerbuff

There reasons why we can't predict to a T how weight loss works in a linear fashion. Some of the reasons:

You DON'T exercise at the same intensity EVERYTIME. Somedays you're just not as good as others.

Hormone regulation ISN'T exact day to day.

You can estimate you output, but unless hooked up to an indirect calorimeter each time to ensure the same exact burn each day, there are still variances.

Rest and recovery matters as well.

Our bodies aren't in a vaccum and each and every day is the same when it comes to how it operates. If it did, then linear weight loss would be much more predictable correctly.


A.C.E. Certified Personal and Group Fitness Trainer
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Been in fitness for 30 years and have studied kinesiology and nutrition

sijomial

pwfkbf wrote: »

https://community.myfitnesspal.com/en/profile/usercard/1009553143, my understanding of the "new diet math" theory is that as we lose weight, the same exercise will burn fewer calories, and additionally, our bodies' thermodynamic response to weight loss is to launch responses to adjust our energy expenditures downward in order to maintain equilibrium. https://pubmed.ncbi.nlm.nih.gov/21872751/ . This researcher argues that these assumptions are not accounted for in older weight loss predictor models, and that as a result, the older models predict faster and more consistent weight loss over time. The research appears to have been undertaken to provide a more realistic long-view of predicted weight loss and, ultimately, of maintenance, so that people form more realistic expectations and understand that our bodies have counter-weight-loss reactions that might help some folks understand frustrating plateaus.

The bolded is simply another assumption - that people do the same exercise. Assumptions and accuracy don't go hand-in-hand.

Most people that take up a new or increased exercise routine as part of a health and fitness drive don't do the same exercise over an extended period of time, they improve and do more. Either higher volume/duration or increased intensity/capability or both.

170lb me burns far more (and eats more) than the 200lbs me ever did. I'm very much in the both category with far more duration and at a higher intensity and c. 25% higher calorie burn rate.

As a MFP specific point someone logging and eating back accurately estimated calories negates the need to make assumtions and predictions about exercise at all.

wilson10102018

Much of calorie consumption is expended in keeping the poorly insulated 200 pounds of mostly water at 98-99 F in an environment of ambient temperature 30 degrees below that. When the 200 pound blob of water becomes a 150 pound blob, guess what ? A 25% reduction in the energy to keep it warm.

lynn_glenmont

wilson10102018 wrote: »

Much of calorie consumption is expended in keeping the poorly insulated 200 pounds of mostly water at 98-99 F in an environment of ambient temperature 30 degrees below that. When the 200 pound blob of water becomes a 150 pound blob, guess what ? A 25% reduction in the energy to keep it warm.

Well, it's not just mass that affects the energy expended for temperature regulation. Surface area also plays a role. For most people I don't think a 25% reduction in weight would be accompanied by a 25% reduction in surface area, so I would think the 150-lb blob would be a shape that would be less efficient at retaining heat than the 200-lb blob (not saying there wouldn't be a reduction in energy expenditure, I'm just thinking it wouldn't be 25%).

wilson10102018

lynn_glenmont wrote: »

wilson10102018 wrote: »

Much of calorie consumption is expended in keeping the poorly insulated 200 pounds of mostly water at 98-99 F in an environment of ambient temperature 30 degrees below that. When the 200 pound blob of water becomes a 150 pound blob, guess what ? A 25% reduction in the energy to keep it warm.

Well, it's not just mass that affects the energy expended for temperature regulation. Surface area also plays a role. For most people I don't think a 25% reduction in weight would be accompanied by a 25% reduction in surface area, so I would think the 150-lb blob would be a shape that would be less efficient at retaining heat than the 200-lb blob (not saying there wouldn't be a reduction in energy expenditure, I'm just thinking it wouldn't be 25%).

Actually, the opposite is true. When weight goes down, the ratio of surface area to weight goes up.