overnight weight loss

[Bob S.]

I usually weigh the first thing in the morning after getting up and voiding but before my first glass of water. Recently, I weighed just before bed for some reason or other that I can't remember. When I weighed again in the morning, I was amazed to see that I had lost 5 pounds. I thought that my memory must have been playing tricks on me, so I did the same a couple of nights later and wrote the weight down before going to bed. In the morning the scale showed a loss of over 5 pounds.

The obvious cause would be loss of water, but, even with two or three trips to the bathroom during the night, I doubt that it would account for even as much as one pound total.

Thinking that it might be respiratory losses, especially in this dry climate, I looked up some respiratory data in Wikipedia and calculated the possible loss. Wikipedia gives an average respiratory rate of 12 breaths per minute and and an average "Tidal Volume" of 1/2 liter of air. That would come to 2880 liters of air taken in an 8 hour period. We keep the house at 64° F (18.8°C) during the night and the relative humidity is about 30%. I assumed that the expelled air was saturated with water vapor at body temperature, i.e. 98.6°F (37.0° C). My handbook gives water vapor pressures of about 15.3 torr at 18.8° C and about 47.1 torr at 37.0° C. Figuring a 30% relative humidity, this would be 4.59 torr of water vapor at 18.8° C, so the increase of water vapor would account for 42.5 torr. Plugging these figures (using 273 +18.8= about 292° absolute for the Temp.) into the gas law gave me about 120 grams or about 4 ounces. Unless I screwed up my calculation somewhere, this would account for only 5% of the observed loss.

I suppose that there is a significant amount of sweat loss during 8 hours of sleep, but I haven't tried to find any data on that. I have also noticed that I sleep fairly warm, so there is obviously some fuel burning going on, but can it account for a weight loss of 3-4 pounds?

Does anyone have any ideas or perhaps additional data on this? I suppose that I should have just done a Barney on nocturnal weight loss, but it was more fun to play games with the gas law.

Bob S.

[Citroen]

I lost about 1lb 12oz weighed before going to bed and just after getting up and emptying my bladder this morning. We only heat the house to 18°C during the day (trying to save money with current energy costs). There no heating at night just whatever is residual from daytime. I don't have a hygrometer in the main part of the house.

[Sheepster]

Here's an article which goes through calculations of insensible water loss during sleep and estimates that 83% of overnight weight loss is due water loss from airways and skin. The article has plenty of calculations for you to play with.

http://advan.physiology.org/cgi/content ... /4/213#top

I also found this article which discusses the relationship between overnight weight loss and sleep stages. They found a positive correlation between weight loss and stage four sleep length (slow-wave-sleep) and higher parasympathetic tone. They also discuss possible endocrine connections although they didn't measure any hormone levels in their study.

http://precedings.nature.com/documents/2342/version/1

[tom pinckney]

This is what happens when one weighs themselves often. You think: "wow - I worked out really hard and I know I lost a lot of weight!"

Then you get on the scale and see" "whoops - I gained a pound!" Then a couple of days later you may see a substantial weight loss.

Sound familiar? Of course. As an expert in weight loss (no I'm not a doctor but have problably lost thousands of pounds in my lifetime due to yo you dieting) I would suggest you weigh yourself once a week at the same time of day after a visit to the "throne!." Unless you are really starving yourself (not a good idea), you will find that you will (usually) weigh less in the morning than in the evening.

[Bob S.]

This is what happens when one weighs themselves often. You think: "wow - I worked out really hard and I know I lost a lot of weight!"

Then you get on the scale and see" "whoops - I gained a pound!" Then a couple of days later you may see a substantial weight loss.

Sound familiar? Of course. As an expert in weight loss (no I'm not a doctor but have problably lost thousands of pounds in my lifetime due to yo you dieting) I would suggest you weigh yourself once a week at the same time of day after a visit to the "throne!." :D Unless you are really starving yourself (not a good idea), you will find that you will (usually) weigh less in the morning than in the evening.

Tom,

I weigh every day for health reasons. I am not trying to lose weight at all. When there is a particularly large fluctuation on any particular morning, I like to be able to figure out why, based on the previous day's activities — like having eaten out and gotten too much salt. The extra water retention due to that often results in a couple of pounds of gain — and also shows up as puffiness under the eyes. A warning to use care if I go to the same restaurant again. A significant drop in weight might indicate that I have neglected to drink enough water and that I am risking dehydration unless I take more care in making sure that I drink often enough.

Bob S.

[Sheepster]

It is interesting observing weight fluctuation both daily and throughout the month. I actually do gain about 5 lbs due to monthly hormonal fluctuations but lose them again the next week. It's funny though, I usually think about "gaining weight" during the day instead of "losing weight" at night.

What I wondered about when I started rowing is:
A rower weighs herself in the morning notes her weight to be 131 lbs and then rows a piece. She logs it as a lightweight. In the evening, she weighs in again and is now 136 lbs (let's say she had chinese food for lunch and hot dogs and potato chips for dinner ) and rows another piece.

Should she log this piece in the lightweight or heavyweight category?

[Bob S.]

What I wondered about when I started rowing is:
A rower weighs herself in the morning notes her weight to be 131 lbs and then rows a piece. She logs it as a lightweight. In the evening, she weighs in again and is now 136 lbs (let's say she had chinese food for lunch and hot dogs and potato chips for dinner ;)) and rows another piece.

Should she log this piece in the lightweight or heavyweight category?

In a similar vein, I weighed before and after doing an erg marathon. I was a heavyweight when I started and, despite a couple of drink stops, I was well below the lightweight limit when I finished. For that year, I just left it at heavyweight. I was going for a good nonathlon score and the nonathlon system does not have the flexibility to allow me to list some events as a lightweight and some as a heavyweight. At my age it doesn't matter much since the LWTs and HWTs perform at about the same (low) level.

Bob S.

P.S. By the way, thanks for the URLs. That is exactly what I was looking for. I was pleased to see that the authors of the first one came up with a number close to mine for respiratory weight loss. The numbers differed somewhat (120g vs. 104g), but that was a result of different starting figures, like 8 hrs sleep vs. 6 hrs sleep and somewhat different respiratory volumes. B.

[Chuck Koehler]

Hi Bob,

I have experienced exactly the same type fluctuations when I am losing weight. Sometimes in the morning I am 5 pounds lighter than when I went to sleep. It is amazing.

I have been logging everything that I eat and all of my exercising and have a calorie deficit of about 2500 - 3000 per day. (BMR + Exercise - Calorie Intake) I noticed that I will lose 3 or 4 pounds over night and then fluctuate back up or stay even for 2 to 4 days afterwards. Then overnight again down 3 to 5 pounds.

When all is said and done I have averaged all of my weight loss for the number of days that I have been eating right and exercising and it is amazing to me that the formula of 1lb = 3500 calories is dead on.

Anyway, I am down 21 pounds since right before Thanksgiving and I have about 70 to 90 more to go so I hope to be able to keep up the pace. My blood sugar has leveled off and is slowly decreasing while my Blood Pressures and Heart Rate are almost athletic at 125/74 and 65 respectively.

Good Luck

Chuck

[BobD]

I hope all of you are using good digital scales with good repeatability?

Test this by getting on and off a few times. Mine always give the same weight.

My experience with analog spring scales shows they are mostly very poor. You can make large changes in the displayed weight just by changing your position on the scales. There are also large changes if you get off and on again.

A good digital scale doesn't notice if you are leaning etc.

[Bob S.]

I hope all of you are using good digital scales with good repeatability?

Test this by getting on and off a few times. Mine always give the same weight.

My experience with analog spring scales shows they are mostly very poor. You can make large changes in the displayed weight just by changing your position on the scales. There are also large changes if you get off and on again.

A good digital scale doesn't notice if you are leaning etc.

The obvious difference between analogue and digital is the display, which doesn't have much to do with the accuracy. The really important point is what means are used to detect the weight. Most simple analogue bathroom scales do just use springs, which are very poor, as you say. The better ones use a balance beam, which has the potential to be quite accurate, if it is well made and maintained properly. I have seen a number of digital display scales on the market and even had one at one time, but it was not all that great and I don't know how the weight was detected. I am curious as to what really is used in various digital scales to actually measure the weight.

I have been considering getting a Tanita, which has a digital display reading to 0.2 pounds and also gives body fat readings. I have read that the body fat values are not particularly accurate, but are consistent so that changes can be detected if it is used under the same conditions every time. My problem is that when I did a Barney on Tanita, I found that they make many, many different models and I couldn't figure out which one would be best for my purposes. I live out in the boonies, where there is no retail outlet that carries Tanita scales, so I can't just go check one out unless I drive a couple of hundred miles to a town that might have them.

Bob S.

[BobD]

As I said, analog spring scales. I have never seen a beam balance scale in a normal bathroom.

The Tanita scales use solid state pressure transducers to sense your weight.

I have a Tanita Digital, and it is accurate to 100 grams, or 3.5 ounces!! Tanita has many models, with the lower accuracy costing less, but they have a good reputation.

The fat measurement is not reliable because it is affected by the hydration of your body. This is a limitation of all electrical methods of measuring body fat.

[Chuck Koehler]

Hello Bobs D & S

I have a Digital Tanita as well that a friend gave to me. It works great and the weight is dead on accurate every time. I try hard sometimes to shift my weight to get different readings but it is very hard to get it to change. At most I can FORCE it to vary about 1lb, but doing that is an obvious distortion. (I have to be leaning or shifting my weight in an grossly animated fashion) In other words it measures the same weight every time.

As to the Body Fat I also agree with you both. It fluctuates a great deal. (for me between 37% and 42% body fat) If you do it at the same time every day with the same body condition it is much more stable. (for example right after a shower after you have dried your feet well) I don't know if this is the most accurate method, but for me it seems to be the most consistent.

I would recommend them in a heartbeat.


Chuck

[PJM]

Another vote here for the Tanita..works well and is accurate.Body fat results will fluctuate a great deal.But with consistent times..you can get a pretty good idea.

Pat

[tom pinckney]

Chcuk wrote: Anyway, I am down 21 pounds since right before Thanksgiving and I have about 70 to 90 more to go so I hope to be able to keep up the pace. My blood sugar has leveled off and is slowly decreasing while my Blood Pressures and Heart Rate are almost athletic at 125/74 and 65 respectively.

Chuck: most of us would be happy to maintain our weight thru the holidays (my goal), much less lose weight. Wonderful info. wondering what else you have done to lose so much weight?

FYI: I had a similar story last year. My blood tests were lousy and now they are pretty good after losing 60 pounds and keeping it off. I've measured my blood sugar prior to erging and then immediately afterwards. It definitley drops!

With the Holiday Challenge to keep it off and the January Virtual Challenge to further challenge us - erging definitley results in a better lifestyle that could save our lives!

[Chuck Koehler]

Chuck: most of us would be happy to maintain our weight thru the holidays (my goal), much less lose weight. Smile Wonderful info. wondering what else you have done to lose so much weight?

I've measured my blood sugar prior to erging and then immediately afterwards. It definitley drops!

Hi Tom,

Well, I was eating really bad and not doing anything. I had absolutely no energy. I had tried several times to get going again but I would work out for a week or two and lose 0 pounds. I went to my doctor and explained how for one I had no energy or motivation at all and that even when I attempted to start there would be no results which completely discouraged me.

I think that a major factor was a Solfonurea (Glipizide) that I was taking for Diabetes. The doctor changed me to Januvia, and also gave me B12 Injections of which I am still taking once a week.

She also gave me Phentermine for a short term kick start, and boy is that working. That's what really gave me the initial boost to get back at the work outs - and it had the added benefit of curbing hunger and elevating my heart rate making the exercise more efficient. Some people are susceptible to high blood pressure with this, but mine was fine, and in fact great.

I am still suspecting that there may be an issue of Hypothyroidism and that the medication is temporarily masking it for now, or possibly even low testosterone. Whatever caused my complete and total lack of energy is at least temporarily subdued. That is why I am working so hard to get back at a routine, and while I can I am Rowing every day.

I am really interested in getting started participating in the challenges that Concept 2 have during the year. (I completed the Holiday Challenge but didn't even know until it was over) Also, I am going to start trying to rank some shorter rows and see if I can reach or beat the 50th percentile. (I logged one of the 10k Rows and I came in on the next to last page of the log) I think that I will do quite well on the 500 meter or 1000 meter times.

As I stated in a previous e-mail, I log EVERYTHING that I eat, and that is one of the keys in my mind. I am averaging around 1300 - 1500 calories intake per day, and that combined with 1300 to 1900 calories burned in exercise every day is really starting to show results. The Diet program that I am using calculates that I am losing 2500 to 3000 calories per day. That is working out to 2 pounds every 3 days.

I have been at 291.5 pounds for the last 4 days so I am expecting a dive any day now. I will wake up one morning and be at 287 or 288, and that will last another 3 to 5 days and then another dive.

Well, I am sure to be boring you with this novel. Keep up the good work and have a great New Year!

Oh, by the way, I am still at a point where my blood sugar goes UP immediately after Rowing. I've read that the muscles store the excess glucose and release it during physical exertion. I think (at least for me) that this build up takes a few weeks to eliminate. Happily it goes down considerably hours and even days after a hard work out!


Chuck