Understanding calories

Is this really fully understood? We are told that burning 3,500 calories is supposed to represent about a one pound loss. According to this calorie calculator, when I enter my weight (154 lbs), and jog for 60 minutes, I will burn 489 calories. So, if I jogged for 7 hours during the week, I would have burned 3423 calories, which is almost a pound. I realize while jogging we will perspire and lose a great deal more in water, so it’s not something you can get on a scale before and after and think you’ve lost more than you really have.

For the last three weeks, I’ve been writing down the results instead of relying on my memory. This is what is puzzling me. I burn way more calories sleeping than jogging. Not according to what I’ve read though. According to the calculator, it shows through 8 hours of sleep I’m only going to burn 517 calories during the night which is slightly more than 1/8 of a lb. How come on average I lose a good 1 ½ lb at night though? I’ve lost as much as 2 ¾ during one night’s sleep, but I was sick that one night. Other nights when I wasn’t sick I’ve lost 2 ½ lbs, and several times 2 lbs, but on average it seems to be 1 ½ -1 ¾ lbs is the norm. I’ve never lost less than a 1 lb.

I wear the same on each weighing which is my underwear. I use the bathroom one last time before going to bed and then weight. I do the same in the morning, using the bathroom first, which thus far has been just been about a half a cup of urine in the morning and then weight. A half a cup (I’ve measured on a few occasions) shows up as ¼ lb difference.

Men are supposed to sweat more than women at night, but I’ve never been much of sweater even while jogging. It takes a lot before the sweat starts to build, and even then it isn’t much, so I just can’t see how I’m perspiring it all away at night and don’t think that it is.

I don’t think this is something really unusual with me, and I wouldn’t be a bit surprised that many of you will be getting similar results on a good nights rest.

One thread I read months ago on Straight Dope showed that others experienced this too. Other Dopers thought it might generally be an inaccurate scale, or temperature difference in the house from morning or night. This and other explanations didn’t add up. To make sure it couldn’t be attributed to a bad scale, I purchased a weight and beam physician’s scale about a month ago which has ¼ increments. I recently bought my brother the same weight and beam scale, and although he’s not monitoring it as close, he’s noticing at weight losses too during sleep, often losing one lb a night or more.

I’m 51 years of age now. I’ve always religiously stepped on a scale morning and night for pretty much most of my adult life. I do remember throughout much of my life and in even in my forties, experiencing as much as 3 and 4 lb weight losses during night, but this was on my old spring scale, and it was difficult to zero in for sure just what the actual weight loss was.

So what am I not accounting for? How can I burn more calories during sleep, than I can by jogging? At least that’s the way I see it, but according to the experts I’m burning way more by jogging. Why do the charts show I’m only supposed to be losing about 1/8 of a pound while sleeping, but my scale shows me losing much more than that? I’ve been trying to figure out what triggers this, thinking maybe some kind of combination of foods might be setting it off by triggering other hormones. Thus far, I haven’t been able to pinpoint it though. If this is well known, why do experts and calorie counter charts often only show a nights rest coming in at 517 calories for my weight?

What’s your experience and what do you think?

Remember that sleeping calorie usage is taken out of your basal calorie ingestion: i.e. that which will keep you at the same weight. I will probably come from blood sugar rather than fat stores.

I would suggest it fairly impossible that, in addition to the weight of your 1/2 cup urine (which sounds not very much to me), you are burning much fat at all while you sleep. Also, the excretion of metabolized fat comes out mostly in your urine too. Are you counting bowel movements in with this too?

I would echo those who speculated that your scales are not that accurate, and have a bias caused by temperature changes.

The human body varies in weight by several pounds a day. If you want a more accurate picture of what you actually weigh, weigh yourself at the same time every day with regard to excretion rather than the time of day, plot the weights on a chart, then take a 4-or-5-day moving average.

“I will probably come from blood sugar” => “It” will too…

“you are burning much fat at all while you sleep” => “you are not burning much fat at all while you sleep”

I put in your edit. A half a cup of urine is a bit low, but on the few times I’ve measured it, that is what it is. This is not something I measure every day, but can get a rough idea by how long I do urinate which isn’t much in the morning. I thought it was going to be more than that, but I assume that’s because I stop eating and drinking a few hours before bedtime, and always go to the bathroom one last time before bedtime too. Thus far in the three weeks I’ve been monitoring it, my bowel movements have been in the afternoon or evening. On one night of some light drinking of beer, even though going to the bathroom at night, I did probably urinate another cup or slightly more than that in the morning.

A couple of degrees difference during night and day has that much affect on a weight and beam physicians scale? I find that very hard to believe even on the old spring scales.

Remember my physicians scale weighs in ¼ lb increments too, and it’s a new scale. I’ve painstakingly stayed on the scale to assure that the beam is as centered as it possible can be to get the most precise measurements I can get with it.

You lose water constantly by breathing and sweating. You sweat even when you don’t feel sweaty - it evaporates (or gets absorbed by clothing and bedding, then evaporates from them).

I can tell you from my weight loss journey over the last nine months that it is nowhere as simple as “calories in/calories burned” as people try to make it out to be. The physics seems simple, but once you get a human body involved in it, it gets very complicated. For example, the amount of sodium you have a your evening meal could affect your weight - if you have a lot of sodium, you might retain water while the sodium in your bloodstream affects your water excretion systems, then you’ll excrete that water when the sodium level drops. Different foods have different insoluble profiles (i.e. poop), too. Then there are your individual differences; you might tolerate and use up some foods better than others, meaning you’d take more calories from them, and others might go straight through you, not giving you much nutrition.

I think at this point with our understanding of calories, excretion, and calorie burning, it makes more sense to go by results than a finely-controlled process - if what you’re eating and what you’re burning results in your weight remaining the same, you’re in balance.

Yeah, to emphasize this, you can lose a lot of water through sweat and moisture in your breath. This is hugely variable, of course. In a cold, moist environment, you won’t lose much moisture at all – maybe a few hundred mL over the course of a day. If you’re physically active in a hot, dry environment, you can easily lose many liters of water. I’ve gone on short hikes through the New Mexico desert where I drank two liters without a single drop of that reaching my bladder.

Most of the day-to-day variability you’re seeing is due to water loss and gain. The signal is mostly noise, you’ll never really be able to account for every little uptick or downtick in your weight. Perhaps the room you’re sleeping in is very dry for some reason (is it air conditioned?); this would lead to a lot of water loss overnight and probably accounts for the variation you see.

Really you should only be concerned with long term averages – over the course of a month, you can more clearly see 5-10 lb weight losses if you stick to diet and exercise. You’ll go mad trying to pick a pattern out of a noisy signal…

Well OK, so where’s that water weight going while you sleep? If you are saying there’s no difference whatsoever in the state you were in when you went to bed, and that when you woke up, minus half a cup of piss, yet there’s 2.75 lbs difference, of which only .25 lb is made up from urine, where is all that moisture going? That’s around 2.5 pints of water. That’s a lot of liquid to come out in sweat and breath. It certainly doesn’t happen to me. Unless your room’s like a sauna.

(Or maybe you sleepwalk and take a dump every night without realising it…?)

Cat Whisperer speaks/whispers/mewls the truth. The body is doing all sorts of crazy things with fuel and production, and while things may balance out on average and in theory, tight correlations with little data and meager control over the absurd number of variables is fruitless–particularly over the short term.

On a side note, your site for calorie counting is pretty vague. What is “jogging”? Plodding along at five miles per hour? Six? Five and a half? Doesn’t gait efficiency make a difference, especially when carried out for an hour? What about shoe weight and similar factors? Is this a number for a perfectly flat indoor track or an average of hills? Are you jogging with huge, muscular thighs or are you building muscle by running on rubbery spaghetti limbs?

Also, what kind of shape are you in? Is it possible that your body is using your rest period to recuperate and rebuild after a workout, and therefore is using energy/calories to do it?

Lastly, are you sure you can make such a direct tie to time-calories-burned to time-weight-comes-off? Calories are a unit of energy, they don’t weigh anything. AFAIU, when you’re burning calories there aren’t a million little fat cells popping open and supplying energy in direct response. There are a lot of other biomechanical processes that take place too, and the breakdown of fats isn’t directly tied to huffing along. Or, more knowledgeable Dopers, is it?

Disregarding emesis, loss of limb, shedding skin cells, accelerating in interesting directions, I can think of only four major ways of losing body weight – defecation, urination, respiration and perspiration.

Assuming you do not urinate or defecate in your sleep, we are left only with perspiration and respiration. Through these you are mostly losing water, carbon (through exhaled CO2), and maybe some electrolytes. If you are indeed noticing 2 lbs of loss through the night, you are losing 2lbs through perspiration and respiration. Which isn’t so hard to imagine. I’ll make up some numbers to get a ballpark figure (Everybody, feel free to correct these if I get anything orders of magnitude wrong):

Assuming normal respiration during sleep is about 5 l/min with 0% inhaled and about 5% of exhaled contents being CO2. Taking CO2 density be 1.5g/l at exhaled temperature should be close enough. This gives us about 0.375 grams per minute of CO2 exhaled. A decent night’s sleep will give us about half a pound of exhaled CO2. And that’s just CO2 alone.

This isn’t accounting for the mass of the inhaled and absorbed oxygen, but when you factor in the moisture loss, I can easily see how you can have several pounds of mass loss overnight.

That’s why we talk about body fat not weight. Your weight can change fairly easily; changes in body fat not so easily. And it’s the body fat that people are usually concerned about.

Nope, that’s exactly where it’s going. Your body needs to add moisture to the air in your lungs, then it exhales it, sending all that moisture out. Every breath you take, it’s much more breathing than sweat.

First of all those calorie counters don’t even come close to being correct. I was involved in a sports med study at the U of Chicago, where they would hook you up to various machines and such.

At 6’ 175 pounds, and 60 minutes of nonstop running at 85% of my theoretical heart rate I burned about 325 calories.

Furthermore your body compensates. For instance, on days when I exercised at night when I slept my body simply lowered all my functions. So the calorie loss was less than expected. This is best seen through heart rate.

On days when I exercised heavily, my average heart rate was only 3 beats per minute, than on days when I didn’t exercise at all. Like my heart rate for the day when I didn’t exercise was 75 and the days I did exercise it’d be 72.

The difference was my heart rate could get to 154bpm but at night it’d fall down to 50 beats per minute. On days when I didn’t exercise, when I slept at night the heart rate remained about 70.

This is why calorie counting isn’t cumulative over the years. If you take steps instead of the elevator you DON’T lose anymore weight. You body will simply compensate for it.

You only lose about 5, maybe 10 pounds through exercise, even heavily exercise.

You simply can’t do enough to use the calories.

To actually change your metobolic rate you need sustained high areobic exercise (85% of your theoretical maximum heart rate), at least five days a week for at least 60 minutes a day, over a period of months.

Just remember calorie counters are going to be 50% to as little as 25% correct. Take into account water weight and weight from things like fiber, which ad weight but will pass through the body.

There is no combination of foods that changes your metabolism in any way other than a few calories a month. (Excluding those with actual metobolic illnesses like diabetes I and thyroid illnesses)

You’re 51 so you need to calculate your theoretical maximum heart rate (220bpm in theory is the most a heart can beat and still pump blood efficently)

220-51 = 169
169 X 85% = 144

So you’re going to be needing to get that heart rate up to 144, 60 minutes per day, at least 5 days a weeks, for a few months before you will see any real change.

In reality it IS as simple as calories in and calories out.

The trouble is people WAY underestimate the number of calories in and WAY OVERESTIMATE the number of calories out.

Everytime I run across friends and I go over their calories, it’s usually underestimated by 30% to 50% and they over estimate their exercise by more than 50%. This is why it’s frustrating.

A few comments:

Calculating your basal calories burned of the basis of weight really is not very accurately done using your total body weight - fat burns much less just sitting there than does muscle and brain. Really you’d have a better chance at some precision using your fat free weight. The point being that a 200 pound athlete with little body fat burns a lot more just sitting there than does a 200 pound couch potato who has little muscle to speak of. A small but not unimportant point. And in a bit of disagreement with Markxxx. More muscle raises your BMI. That’s why the most fat loss comes from a good diet habits coupled with an exercise plan that include both some aerobic and some weight training (resistance) component.

The bigger point: you may indeed be burning more calories in your sleep than that calculator assumes. No, not two pounds worth, but still.

One thing we do know - lack of sleep is associated with a person gaining weight.

How many calories are we really burning in our sleep? Well if you are active during the day then you are some repair work that gets done in your sleep, repairing worn tissues, etc. (Anabolism) That takes energy. And dreaming burns it up. Our brains actually burn a huge amount of calories and REM is a very active time . The human brain makes up “only two percent of the body mass of an adult human, it utilizes twenty percent of the total (resting) energy consumption” and dreaming is very energy intensive.

Yeah, still not likely two pounds worth.

The conventional wisdom is that a person burns around 100 calories a mile, give or take a few hundred depending on speed. Actually, of course, work performed accounts for calories lost, so if you run 6 miles in an hour you will burn more than if you run 5 miles in an hour. The efficiently is a minor factor, and being inefficient (such as walking) will not add much more. And work performed has to factor in your weight. So Markxxx’s comment that he burned only 325 sounds in an hour (running at 85% MHR) to me incredulous. In addition, the formula he gave for obtaining MHR applies only to sedentary people. There is no adequate formula for people who have been long-time runners, although I’ve read some attempts to do so.

If you eat 3 pounds of food before you go to sleep, you will gain 3 pounds. The food has to be metabolized, waste being excreted in the form of water, gas (mostly CO2 :)), and solids, while nutrients are digested. My weight is always a few pounds lower in the morning after my morning bowel movement than it was the previous night.

Read this article from last Sunday’s New York Times (Reg Req):


But … but… but my treadmill said I burned 925 calories! It’s electronic – that means it just CAN’T be wrong!
I’m in my fourth month of holy-shit-what-the-hell-happened and am just about ready to participate in one of the monthly weight loss threads (waiting for May). I must say that in my experience (which, as anecdote, admittedly isn’t all that valuable) calorie counting in and out has been pretty useful–though I generally round to the nearest hundred and do my best to overestimate in and underestimate out.

After averaging a slew of online calculators for daily needs, phase 1 (January) focused on dropping intake from who knows how much higher than needed to as close to five hundred to a thousand or so under per day. Phase 2 (February) brought in the treadmill, an hour on it every other day (silly me and the spaghetti legs are building muscle on it to carry me along, so I’m considering the days between as recovery days. When I can comfortably run for the full hour I’ll shift to every day). Phase 3 (March) brought in the heavy objects during the three or four days per week between cardio (this too will change as steady-states are reached. Right now it’s the best we can do). The loss has fluctuated a bit, but on average it’s maintained a steady two pounds per week (in total, I began at ~235, now at ~205).

So calorie counting? Without some guidance I’d have no idea what and how much to eat. Forget about just cutting out pizzas, beer, bacon, and choco-cake, there is still a sizable deficit to meet in order to lose weight. And thanks to our good friends at Penseys, we can cook up a plethora of dishes with no processed foodstuffs and hardly any calories. It is a lot of guessing, but as exercise has grown in intensity we’ve had to do something to compensate for the additional intake need–else we’d have moved into more-than-a-safe-two-pounds-a-week territory.

So in the recent couple of months our output has increased along with a very slight increase in intake. We’ve been very carefully writing everything down, so keeping track has been a bit easier.

Is there a link to this study anywhere? While I agree that when I was losing weight, the easiest path was through diet, the exercise I did (5-6 miles of running, on average, a day while maintaining an 1800 calories diet) seemed to have the predicted effect on me. Without the exercise, I was burning about a pound a week. With the exercise, I was losing two pounds or slightly more a week. I have weigh-in charts and food diaries that track this information. It tapered off a bit once I dropped down to the 165 pound range, but it seemed to me that when I ran 6 miles (about 45-48 minutes for me), I really did burn off around 700 calories or so.

I wonder how much the individual variance on this is, and, if what you say is true in general – I have no doubt in your circumstances the information was correct – why this hasn’t been better publicized by those from the diet industry.

I gave that some thought even before writing my OP, and if I was to guess, I’d say this must be it. Most seem to agree with you.

That will be another thing I’d like to monitor more closely next time is the sodium level, and how much water I’m retaining because of that.

I appreciate everybody’s feedback, this has been more enlightening than the last thread when this was done months ago, where quite a few were claiming it was a bad scale or claiming the temperature differences in the room between night and day were enough to cause the scale to read wrong. This is why I went and got a weight and beam scale this time, so that hopefully would eliminate everybody concentrating on that.

Exactly - and if you think about it, 2.5 pints over 8 hours spread across an entire room is not noticeable. You breathe all day, every day, 24 hours a day. It adds up!