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Does drinking lot of water help lose weight?

Red Squirrel

Red Squirrel

No Lifer
I heard this, but is it really true? How does it work? I often hear of people talking about diets and say that their first week they lose a lot because of all the water, but if I'm putting lot of water in my system, then wont that make me gain?

I figure, if it does help for weight loss and overall health, then it's very easy to do in the evening when I don't need to go anywhere, so I do it, but if I'm wasting my time and wasting toilet flush cycles, then I wont bother. The only downside of this is it's not really something I can do during the day at work unless I want to spend 90% of my time in the washroom peeing.
 
No, drinking a lot of water doesn't help you lose weight. Staying well hydrated increases your performance overall, but will not make you burn extra calories.
 
It's not the drinking of water that helps you lose weight, it's the not drinking of something else(like soda, juices, etc) that helps you lose weight. If you drink a bottle of water when you're thirsty, then you reduced your caloric intake for the day by 200 calories if you normally would have drank a bottle of coke instead. And it adds up over time.
 
RedSquirrel said:
I heard this, but is it really true? How does it work? I often hear of people talking about diets and say that their first week they lose a lot because of all the water, but if I'm putting lot of water in my system, then wont that make me gain?
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Water can temporarily fill your stomach and semi-trick you into feeling satiated for a short time. Combined with a meal, especially with fiber, I find the effect is a lot better than on an empty stomach. The other big thing is that people mindlessly mistake thirst for hunger, and eat instead of drinking. Very easy to make that mistake. So upping your water intake, especially if that water is replacing some calorically-laden drinks, is a good thing. If you're already well hydrated, you're not going to gain much. You're just going to pee a lot.

Much of that huge initial water loss comes from burning up some of your stored glycogen, in your liver and muscles. Water binds to those glycogen molecules, so when the glycogen gets used, the water heads for the exits. (When the mega-fatasses on Biggest Loser dump 20+ lbs that first week, you can be sure that a lot of that was water that was pissed and sweated out).

When you eventually refeed and replenish the glycogen, you'll retain water and the scale will bounce back up some. Which is why it's pointless to obsess about 5 or even 10 pounds of water weight. It comes and goes.
 
People usually say this because if you drink more water and not Soda, Juice, etc, then you are cutting your daily consumed calories down and losing out on loads and loads of sugar which will help you lose weight.

It is not drinking water that makes you lose weight, it is not drinking something else in its place.
 
Ah makes sense, so it more or less acts as a substitute to having a soft drink, or even food, when you're not really hungry and just thirsty.
 
Hi, long time (maybe about 12 years...) lurker, first time poster.

You're all mostly correct, but technically you do burn calories by drinking water. It takes 37 kcal to raise 1 liter of ice water to body temperature, so a day that includes drinking 2 liters of it, or any other 0 degree C beverage, actually burns about 75 kcal more than drinking the same amount of something warm.

----------Edit:

Also, thanks for the great ATHF forum. I hadn't even noticed it on the boards until a few months ago, but the Fat Loss Sticky is great and the discussion here is a lot more civil and less annoying than the flamewars on most of the other fora. Since I started checking out this forum I lost 20 pounds, started running for the first time since high school 10 years ago and got my mile time down to 7'30", increased by bench by 50 lbs, my squat by 100 lbs, and other good things as well.
 
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McWatt said:
Hi, long time (maybe about 12 years...) lurker, first time poster.

You're all mostly correct, but technically you do burn calories by drinking water. It takes 37 kcal to raise 1 liter of ice water to body temperature, so a day that includes drinking 2 liters of it, or any other 0 degree C beverage, actually burns about 75 kcal more than drinking the same amount of something warm.
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While this is technically true, it really won't make a difference in the long run.

Drinking water and tea instead of sodas and juices will reduce calorie intake by a lot for many people.
 
Actually I was going to ask about the temp thing too. I had heard that drinking very cold water sorta helps, but guess it's super insignificant.

Guess the #1 thing to losing weight is intaking less calories then you burn in one day. Or is there a bit more to it then that? It just seems too easy if that's all it is, yet so many people struggle with losing weight.
 
I've been drinking water straight for a month or two now, and it's done nothing...I only drink water with ice. (For a week or two in January, I did drink soda because of traveling, and I do still drink milk). I don't mind it though and continue it.
 
I had a high school science teacher who was very smart, and a great teacher. He was also very much overweight. He claimed that he could lose all that weight if he wanted to easily. All he had to do, he said, was drink lots of water and hydrolysis reaction would break down all of that fat.

It seemed so far-fetched but I thought maybe it was possible because he was a science teacher who was saying that.

This was back before the days of the internet, so I really wasn't going to easily research that claim to see if it was true. I've never heard of anyone simply drinking tons of water to lose weight, so I'm going to have to assume that it is not true.
 
RedSquirrel said:
Actually I was going to ask about the temp thing too. I had heard that drinking very cold water sorta helps, but guess it's super insignificant.

Guess the #1 thing to losing weight is intaking less calories then you burn in one day. Or is there a bit more to it then that? It just seems too easy if that's all it is, yet so many people struggle with losing weight.
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your body uses energy to heat the cold water so i guess that could contribute to weight loss...
 
That cold water factoid has been posted all over teh interwebz and probably goes back many years before that. It's still wrong.

As a living organism, calories are being burned every minute that you're alive, regardless of what you're doing. In the process, a lot of heat is generated (~60% of the energy that goes into cell respiration is lost as heat). Some of that heat goes toward maintaining 98.6, and under normal room temp conditions, the rest has to be dumped to the environment to keep your organs from frying.

So there's some amount of excess heat on tap at any moment, "free" heat that can easily be rerouted by the circulatory system to go to the stomach to warm it up. You don't have to burn a bunch of extra energy solely to warm up your stomach. I suspect the thermogenic effect of drinking cold water in any practical pattern is almost negligible.

That simple q=m*c*deltaT calculation might be appropriate if we were talking about pouring water into a styrofoam cooler, not the human body.
 
Doesn't sufficient water intake promote healthy kidney function which, in turn, promotes healthy liver function?

In a nutshell: Does too little water hurt the body's ability to metabolize fat through the liver's processes?
 
SludgeFactory said:
In the process, a lot of heat is generated (~60% of the energy that goes into cell respiration is lost as heat). Some of that heat goes toward maintaining 98.6, and under normal room temp conditions, the rest has to be dumped to the environment to keep your organs from frying.

So there's some amount of excess heat on tap at any moment, "free" heat that can easily be rerouted by the circulatory system to go to the stomach to warm it up.
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Draw a black box around the human body, at the skin-air interface. There are two possibilities here.

1) Your skin temperature is lowered when you drink the cold water, reducing heat loss to the environment. Then the extra heat your body is generating is leaking out of your black box at a slower rate, because the rate of heat loss through a boundary layer is proportional to the difference in temperature between one side and another. This is what you're suggesting.

2) If your skin temperature doesn't drop, then the rate of heat loss to the environment stays the same. Therefore you maintain the same level of extra heat generation to the air and must lose an additional chunk of energy to warm the water.

Obviously the real case is a combination of 1 & 2, but which one is dominant? You suggested 1 and I suggested 2. A bunch of MD-PhDs and physiologists believe that case #2, as I originally suggested, is correct. One example (many others of which are available with an easy search):

http://www.chow.com/stories/10877

It would take a pretty significant and sustained drop in skin temperature to make up for the 37 kcals in a liter of water.
 
For what its worth - you can lose "weight" by drinking water, assuming you aren't properly hydrated to begin with. Its water weight. It isn't actually fat you're losing, and it won't continue beyond the first couple of days.
 
McWatt said:
Draw a black box around the human body, at the skin-air interface. There are two possibilities here.

1) Your skin temperature is lowered when you drink the cold water, reducing heat loss to the environment. Then the extra heat your body is generating is leaking out of your black box at a slower rate, because the rate of heat loss through a boundary layer is proportional to the difference in temperature between one side and another. This is what you're suggesting.

2) If your skin temperature doesn't drop, then the rate of heat loss to the environment stays the same. Therefore you maintain the same level of extra heat generation to the air and must lose an additional chunk of energy to warm the water.
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What about latent heat losses due to sweating? You could have a third option:

3.) Skin temperature remains constant. Some heat is lost due to normal conductive and radiative heat transfer (considered in 1 and 2). Additional heat is lost in the form of latent heat when sweat evaporates. The amount of evaporative heat loss can be regulated by controlling the amount of sweating. Drinking the water causes a drop in core temperature, resulting in a reduction in the amount of sweat released and a reduction in latent heat loss. Skin temperature and thus conductive and radiative heat transfer can remain constant.

A quick thermodynamic calculation shows that you'd only have to evaporate about 13g less sweat to make up for all of the 8kcal that goes into warming the water.

Of course, I don't know whether 13g of sweat is significant (exercise rates seem to be around 13-24g/min, so it may be too large an amount to regulate at rest). I also have no idea whether there is a metabolic cost involved with sweating or how big it might be.
 
If you want to get into that much detail, and honestly it seems pretty justified since the point of my first post was digging into meaningless detail anyway, then we should consider evaporative cooling through the lungs. Increasing your level of hydration may increase the loss of moisture through breathing, thus further cooling you.

Also, more hydration may slightly smooth out wrinkles in the skin, reducing the thickness of the boundary layer in the surrounding air, promoting cooling. But smoothing wrinkles may also reduce the surface area of the body, reducing cooling.

So I can clearly not choose the goblet in front of me.
 
McWatt said:
Draw a black box around the human body, at the skin-air interface. There are two possibilities here.

1) Your skin temperature is lowered when you drink the cold water, reducing heat loss to the environment. Then the extra heat your body is generating is leaking out of your black box at a slower rate, because the rate of heat loss through a boundary layer is proportional to the difference in temperature between one side and another. This is what you're suggesting.

2) If your skin temperature doesn't drop, then the rate of heat loss to the environment stays the same. Therefore you maintain the same level of extra heat generation to the air and must lose an additional chunk of energy to warm the water.

Obviously the real case is a combination of 1 & 2, but which one is dominant? You suggested 1 and I suggested 2. A bunch of MD-PhDs and physiologists believe that case #2, as I originally suggested, is correct. One example (many others of which are available with an easy search):

http://www.chow.com/stories/10877

It would take a pretty significant and sustained drop in skin temperature to make up for the 37 kcals in a liter of water.
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I think you underestimate the thermoregulatory abilities of your body, the heat transfer provided by 5 L of blood with a heart that can pump 5 L/min, the heat capacity of an average 150 lb body, etc etc.

The water is hitting a warm upper GI tract and you're getting convective heat transfer right away over a lot of surface area, with fairly rapid vasodilation of the network of arteries to get warm blood there ASAP. You're pulling warmth from all the extremities, skin temps can drop by a few degrees, especially as you go more distally. Your feet/hands/arms will probably get cold, it's quite likely you'll want to reach for a jacket in your 70 F house if you drink enough of this to do much of anything -- thereby insulating, cheating, and defeating much of the purpose of doing it. But here's some back of the envelope stuff:

Going off of this, vasoconstriction alone can reduce overall skin heat flux by 25%. As mentioned, latent heat from sweating and lungs is also a factor, it makes up anywhere from 20-40% of body heat transferred to the environment at normal room conditions (from ASHRAE tables). Sweating should reduce drastically in our hypothetical scenario. Conservatively, just between those two mechanisms, and giving some metabolic and inefficiency penalty for your body having to work to make this happen, let's say you can effectively reduce and redirect overall heat loss by 30% for some period of time (30 minutes, semi-educated, semi-wild-ass guess).

Sitting at rest/at the computer, you're transferring 86-103 kcal/hr of heat (ASHRAE). If you can redirect 30% of that to your viscera over 30 minutes, that's 13-15 kcal -- which comes close to canceling out the 18-19 kcals it takes to "warm" a typical 500 mL bottle of water. And that's if you're sitting around doing *nothing*, waste heat will double or triple with real activity.

So you drink the 500 mL, 4X a day, and you're looking at what, thermogenesis of 20 kcal or less? That's negligible. Sipping or casually drinking this stuff is going to be pretty much ineffective, there's enough heat capacity in your body that it'll basically just laugh it off. Everything in the real world is rate limited, it seems to me your best shot at making this work is to chug it, and I still bet it's going to be about half as effective as what they predict. I'm talking about bombing your gut with 1 -2 liters of freezing water. I've never tried that. I would anticipate pain and probable stomach cramps and having to piss urgently at least 4 times over the next 90 minutes. Some would rather just park at the back of the parking lot and take the stairs at work and burn a few dozen calories that way.

Decisions, decisions.
 
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I don't find a bunch of MD-PhDs agreeing with this either. The example you linked to is from a guy with a Public Health degree, not a PhD, and hardly a research scientist. If you do the easy search you suggest, a lot of articles with this factoid in them are coming from bloggers or dieticians at best.

In real scientific literature, I find *one* research group that's attributing a significant "water-induced thermogenic" effect, along with a substantial cold-water effect. A followup study by Brown finds no water-induced thermogenesis, a minor cold-water thermogenesis, and lists 10 or so prior studies that found no water-induced thermogenesis either.

For the cold water test, Brown had his subjects drink a half liter of 3 C water in 3 minutes, and got ~3.6 kcal of additional energy expenditure over 90 minutes. And that's basically guzzling a 500 mL bottle in 3 minutes, not sipping.

Extrapolating to 500 mL x 4 bottles per day, that equates to 15 kcal worth of cold water thermogenesis over the course of the day. Negligible, even in the context of a reduced calorie diet (1500 kcal). Chew 3 pieces of sugarless gum and you've just ruined the 2 liter cold water trick.
 
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