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# The New Weight Loss Calculator

By +Carolyn Richardson on Sep 29, 2011 10:00 AM in Tips & Updates

Between lean body mass, body fat percentage, water weight, metabolism, and prior diet and exercise, losing pounds has many variables, and caloric deficit is only one piece of the equation.  To get a more accurate picture of weight loss over time, researchers at The National Institutes of Health (NIH) recently created a mathematical model and online simulation tool that accounts for these variables.

The Body Weight Simulator

The baseline information the tool uses includes the usual: age, sex, physical activity level, and initial weight.  The results corroborate what calorie counters already know: an active 50-year old woman at 150 pounds and a sedentary 17-year old boy at 300 pounds will lose weight differently.  Developed at the Lab of Biological Modeling of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the Body Weight Simulator may offer new information many weight loss hopefuls may have yet to consider.

Baseline Diet

Once you input the baseline information the simulator gives you baseline diet information in the form of a current caloric intake per day.  Seeing this number could give you an ‘I didn’t know’ moment.  Because so many people starting a diet have little to no clue how many calories they're consuming daily, seeing this estimate could be a much needed reality check. What’s more, examining approximately how much food you eat now can help you find a middle ground between an extreme reduction in calories and one that is more realistic.

Goal Weight vs. Lifestyle Change

As available on most sites, inputting a goal weight and a certain amount of days will return a change in physical activity and daily calories to stick in order to reach your goal by a certain date.  But it doesn’t stop there.  The results are charted by day, giving a representation of how weight loss progresses, not only in pounds, but also in body fat, and more importantly energy expenditure.  The chart exposes something most people may not think about while dieting: as you lose weight you burn calories differently.  The same concept is true for the lifestyle change option.  Comparing the two options’ results can reveal how either diet and exercise alone or both can affect your weight loss over time.

Weight Change vs. Goal Maintenance

Another facet of the simulator is the consideration of two phases of weight loss.  Many people have all the numbers lined up of how to lose weight, but may not know how to maintain their weight loss.  How many more calories and how much exercise will help you stay at your goal weight is important to determine at the beginning of your weight loss program.  The simulator answers these questions through the tabulated data that shows your caloric intake and expenditure after you reach your goal weight.

Researchers are hoping to use clinical trials to improve it.  For now, use the simulator wisely as it may give information for daily caloric intake and physical activity that may be outside the healthy range of weight loss of up to two pounds a week.

DISCLAIMER: The information from The Body Weight Simulator is for general research use only and is not intended to provide personal medical advice or substitute for the advice of a physician or weight management professional. If you have specific questions about the information presented, concerns about individual health matters or body weight management, please consult your physician.

What results from the Body Weight Simulator are you interested in seeing?

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Comment Removed

works for me, though it's incredibly slow to load

Depends on what a person is using for a computer I guess. Mine loads in moments.

Interesting simulator. I'll need to take a closer look to take in all the info that it provides.

Really useful little tool. Shocked at how little calories I'd need to eat to lose weight in the time I'd like. Totally unrealistic!

Even I am looking forward to use this calculator. At least I would get an idea about my target body weight. :-)

I thought it was great... very informative when you click on the tabulations.

Personally, i found that the caloric intake suggested was very similar to what CC gave me. And i liked that it gave realistic options for activity levels. With CC i have a hard time deciding what to choose as it seems to jump from completely sedentary to a whole lot of physical activity and i'm somewhere in between.

At first it didn't load for me as well, then i realised i needed to download Java. lol  (brand new computer so i didn't have it yet.) There is a link to Java on the start page. Hope that helps.

I used the calculator.  There is no way I could consume that many calories and lose weight.  Their calculator says I should eat 1546 calories.  I'm currently at 1200 and having a difficult time.

bkmp66, I'm one of those persons who gains at 1200 calories-- very survivor oriented body!-- and when I bumped to 1500 cal.-- I started losing again.  You may have the same problem.  Took a long time and many trials to prove the point-- but that's the way it is for me.    Good luck.

Where is the new onw at?

I've been in maintainance mode for 2 months now, and I'm eating around 1,500 cals a day. The calculator has me eating over 2,000 cals a day to maintain my 128 lbs. Quite a big difference huh? I too had been eating around 1.200 cals a day and was struggling with the "last few pounds" After I bumped up the cals to about 1,520 a day, those stubborn lbs. came right off, and stayed off. At 1,200 cals. I was wondering why I was hungry all the time. DUH.........I wasn't eating enough. The 300 cals. extra made the difference between going to bed hungry and being satisfyed.

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Fancy, yet pretty much useless if you're interested in changing your body composition ie getting leaner.  I see BF % on there, but no way to change it.  I'd like to see these organizations put some effort into developing lean body mass calculators and helping people understand that lean and muscular is better than average and flabby.

OK, just saw you can adjust starting BF % using the advanced controls.  Still would be nice to see some calculators there for it.

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It has me eating 2130 calories, that seems crazy. I can barely get in 1800 with it all being healthy. I don't want to eat bad to get to the calorie intake that is required

Loved it, thanks!

I can't get to the calculator.  Is there another link?

I tried to use the simulator. I went through the entire tutorial, and still couldn't figure out how I'm supposed to make it work.

Interesting information for sure.  Although not a whole lot different from CC.  CC does provide a more simplified, user friendly view.

Quoted from article, "Because so many people starting a diet have little to no clue how many calories their consuming daily." Should be "they're" not "their." It is a contraction for "they are." ...no clue how many calories THEY ARE consuming.

It's pretty good but I can't figure out how it is calculating my bodyfat.  I am no where near 21-22%  I have abs showing for gawds sake!  You don't have abs at 21-22%!!!  Otherwise it's calculations for calories were pretty close to what I have been doing.  1700-1900 calories with light work day and strenuous workouts during off hours a rating of "2" for activity level.  22% my ****...

Original Post by: ds1973

OK, just saw you can adjust starting BF % using the advanced controls.  Still would be nice to see some calculators there for it.

Oops missed that...  8/

I am unable to link to the calculator......

It is surprising to see how much I can eat to still lose but I believe it.  I also had an issue when I went down to 1200 calories (as the CC calculator suggested), now that I've increased my intake to 1400-1500 or so plus a tiny bit of exercise I've had MUCH better results and I'm not miserable and hungry.

Felt my BMR rate was way too high! If I ate the calories it gave me to lose, I'd actually end up gaining...

I love this tool! I especially like it's emphasis not just on calories, but lifestyle, although an expansion of lifestyle change options would be good. The problems people describe here about unrealistic calorie estimates might be a function of the activity level stuff.

another tool that does not work for me.  i am 5'7" tall and weigh 214 with a body fat index of 17. i work out 7 days a week with various exercises but 3 times a week involves weight lifting. this simulator is telling me my body fat is 36.9. it is as worthless as the bmi  way of measuring fat or anything for people heavily muscled. i am 70 and have worked out since about 14. it says to eat 3328 calories to lose 14 lbs in 6 months. i eat around 2100 calories a day now and have not lost anything. i guess i will pass on this simulator thing.

I've always told my guitarist friends that if they really want to shred those pounds the "bassline" diet always works. It's shook more booties and elevated more heart rates than a Jimmy Page solo ever will.

Original Post by: 2laura

bkmp66, I'm one of those persons who gains at 1200 calories-- very survivor oriented body!-- and when I bumped to 1500 cal.-- I started losing again.  You may have the same problem.  Took a long time and many trials to prove the point-- but that's the way it is for me.    Good luck.

Based on cc recomendations I had been strictly adhering to 1200 calories a day.  I lost 20 punds in two months.  For the next 15 months, I strictly adhered to 1200-1300 claories a day with 500- 1000 aerobic calories burned a day.  I didn't lose a single pound.

I incorporated wight training, cut back on the aerobic activity quite a bit and upped my calorie intake to about 1800 a day.  I've lost 12 pounds doing that in about two months.

It might make sense to eat a little more for a little while.  I think the body 'hoards' when it's not getting enough food making weight loss next to impossible.  It really doesn't appear to be as simple as calories in vs calories out.

Good luck!

My biggest issue with this calculator is that it assumes you will loss Lean Body Mass.

It estimated my LBM as 145 lb. to start and 120 lb at my target weight.

This was with a conservative weight loss of 55 lbs over 81 weeks.

Almost half of my weight loss being Lean Body Mass?

No way.

No problems downloading the simulator here. I found that the number of calories it suggested I eat to maintain was a little higher than what I've been experiencing IRL. Good tool, though.

I used the calculator to see if it accurately represents the progress I have made so far.  My initial weight was 203.7, current weight is 186.8 lbs, after 42 days have elapsed.

Using 2.8 lbs/wk average loss as above, I calculated my daily caloric intake need was about 3200 calories.  I have been dieting at 1600-1800 cal/day, leaving a deficit of about 1400 cal/day, which matches quite well with their simulation.  This suggests their caloric intake vs BMR simulation is quite accurate and I highly recommend it for that.

One thing their simulation did confirm is that if I increased my activity level, I could lose weight faster and/or reach my end goal weight at a slightly leaner body fat percentage. Simulating the addition of quite a bit of physical activity, it seemed like it should've made a little more than 0.1-0.2% body fat difference after 6 months (I used a 400% increase in activity, which is not realistic).  I am not sure I completely trust that part of the estimate. I think that needs a little more work.

In any case, it's a very good start.

Original Post by: tom_murphy

My biggest issue with this calculator is that it assumes you will loss Lean Body Mass.

It estimated my LBM as 145 lb. to start and 120 lb at my target weight.

This was with a conservative weight loss of 55 lbs over 81 weeks.

Almost half of my weight loss being Lean Body Mass?

No way.

If you achieve your weight loss by dieting alone, and do not increase your activity level, it is true that not only will you lose fat, but some percentage of the weight loss (25% I seem to remember, never saw 50%) will actually come from loss of muscle.  This is the primary reason why you will almost never see a legitimate weight loss program promote diet alone as a way to lose weight.

I do think that 50% is a little high, but if you are relatively sedentary, I suppose it is possible?

Main issue with this is if you enter a long term goal. ie. weight loss over a year, it gives you a calorie total as a constant for the whole year. The way I'm doing things is I'm dropping my calories as my weight drops to maintain the same deficit. Be good to see that incorporated in it.

Original Post by: kessler1892

Main issue with this is if you enter a long term goal. ie. weight loss over a year, it gives you a calorie total as a constant for the whole year. The way I'm doing things is I'm dropping my calories as my weight drops to maintain the same deficit. Be good to see that incorporated in it.

That would be next to impossible...  That is assuming your weight loss is directly relative to calorie reduction.  In some cases yes but in most cases no.  Just because you say you are going to exercise or eat less does not mean that you will...  Too many variables.  That is why you are supposed to us eit as as a tool for current weight etc.  You wanna know what it will be again when you lose 10 pounds?  Use it again after you have lost 10 pounds.  It's not a genie that predicts the future.

I can"t get to through to the calculator, either.

This tool said I should be eating 441 calories to loose weight in 100 days. I am 153 now and my goal is to be 145 by November?? It could be that I just didn't under stand this tool. TO me it seemed a bit complicated with a lot going on at once. Not easy to read at all.

Original Post by: ritchiep

Original Post by: tom_murphy

My biggest issue with this calculator is that it assumes you will loss Lean Body Mass.

It estimated my LBM as 145 lb. to start and 120 lb at my target weight.

This was with a conservative weight loss of 55 lbs over 81 weeks.

Almost half of my weight loss being Lean Body Mass?

No way.

If you achieve your weight loss by dieting alone, and do not increase your activity level, it is true that not only will you lose fat, but some percentage of the weight loss (25% I seem to remember, never saw 50%) will actually come from loss of muscle.  This is the primary reason why you will almost never see a legitimate weight loss program promote diet alone as a way to lose weight.

I do think that 50% is a little high, but if you are relatively sedentary, I suppose it is possible?

Thanks for the comment.

I did add moderate walking as a cardio activity so I assume if I had left it at sedentary the number would have been even worse.

I didn't see an activity option for heavy strength training.

Ideally adding this option would GREATLY reducing the amount of lean body mass lost over the course of the simulation.

I am not striving for a smaller version of the present me.  I want to reduce body fat while retaining lean body mass.

Thanks.  That link worked.

It says that I should eat about 500 calories a day... How is that possible?

I filled the thing out and it told me to eat 372 calories a day to reach my goal. Somehow I don't think that's right..............................................

Original Post by: fraulyda

The link to the calculator doesn't work???

Have you tried opening it in a new tab? Also, you need Java Script to view it.

Original Post by: philfan1

I've been in maintainance mode for 2 months now, and I'm eating around 1,500 cals a day. The calculator has me eating over 2,000 cals a day to maintain my 128 lbs. Quite a big difference huh? I too had been eating around 1.200 cals a day and was struggling with the "last few pounds" After I bumped up the cals to about 1,520 a day, those stubborn lbs. came right off, and stayed off. At 1,200 cals. I was wondering why I was hungry all the time. DUH.........I wasn't eating enough. The 300 cals. extra made the difference between going to bed hungry and being satisfyed.

I haven't been eating as much recently and- believe it or not- gained a few pounds. Yes- your body can be and is smarter than we are at maintaining itself or surviving.

Although, the signs of me going through some other "changes" have appeared sooo my metabolism could be changing :p

This thing is completely off.  It says my baseline estimate is 2,300 calories A DAY -totally FALSE.  I haven't eaten that much a day in years, and in fact, that's almost double what I've been eating for quite some time (I'm very tiny, 5'2" with a small bone structure). I have issue with any calculator telling me how to lose weight, though; even the more specialized ones are very "one size fits all."

The calculation seems a bit off for me too.  I've been trying out some new diet trackers/calorie counters and found a cool one called OnTarget Nutrition.  It's the best diet tracker by far I have found so far.  It also calculates the daily calorie target and it's really accurate, and the weight loss goal is included in the calorie target.

If anyone wants to check it out:

www.ontargetnutrition.com

Okay, it gave me some VERY whacked out results.  I am losing weight at a bloody SNAIL'S pace, eating 1800-2000 calories per day and exercising like a fiend.  The calculator said I can lose 28lb in 180 days by eating 2100 calories with my current active lifestyle.  That's adding 300-100 to what I already eat, and I am NOT losing 4lb a month as it is!  At the same time, I see a lot of success stories on CC where someone at age 40 (who supposedly has a slower metabolism than I do) drops 30 lb just because they stopped eating 20 cupcakes a day or 2 whole pizzas at once, and by walking for 30 min a day.  I do 60-90min hard cardio a day and was never prone to binging but my weight loss rate sure isn't what you'd call a "success."  Maybe the calculator is correct for the success stories on this site, but I am starting to think my body just doesn't work the way other peoples' do, and that maybe none of the calculators I've tried are even close.

I plugged in values for my current weight and also for my weight and activity level, when I was 25.  I was much lighter and more active then.  I plugged in different values for activity levels and noticed it shows the same body fat in weight and percentage, regardless of activity.  This is not right.  If you are more active, you should have more weight in muscle and thus less in fat.

I tried it and it proposed quite high calorie intake for me to lose weight. I know I cannot for a fact, but everyone is different. It is just an idea. Very rough idea.

Am I missing something?  I get to the calc, can run it etc....but how are you supposed to "download it"?  I see folks on here say they did that.  I mean to kepp my numbers in it & use it on my computer from time to time to update it.  Thanks anyone.