 Hey everybody, Dr. O here, in this video we're going to talk about fluid balance, we're going to talk about balancing our water gains, fluid gains with our fluid losses. So the first question is how much fluid should you consume, should you drink, and should you eat? Well, depends on how much you should lose, or how much you lose. So we'll look at those two and then we'll talk about some exceptions to that rule. So let's talk about gains first. So we have to balance the gains of fluid, which is the water that we drink, we eat and we make. So as you see here, fluid intake about 1200 milliliters, water in food, another 1000 milliliters, and then 300 milliliters, I always say usually about a cup, somewhere around a cup or eight ounces of water is produced metabolically as you're producing ATP. Remember glucose plus oxygen makes carbon dioxide plus water plus ATP. So that's going to be your fluid gains. We drink it, we eat it and we make it. And we're going to balance that then with our fluid losses and our primary fluid loss is going to be urine as you see here. I always like to say that we pee it out. We breathe it out. So it's going to be the fluid that's lost from our lungs there, that 350 milliliters. And then we sweat it out. And you see there are 350 milliliters from the skin. The fourth one would be feces. So we have to balance those two out. So generally speaking, the average male would need to consume about 3000 milliliters a day of fluid from all these different gains. And for a female it'd be about 2200 milliliters. So that's where you get this 2500 number. So 3 liters for males, 2.2 liters for females. But obviously you can see a ton of variation here. Let's say that it's not humid, you're not hot, you're not exercising, then these numbers are going to be pretty good. You're going to produce urine. You're going to have some insensible perspiration or insensible water loss from your skin. So it's sweating that you're not aware of, not pouring buckets of sweat. And you're going to be breathing out some fluid as well. That's the number there for the lungs. You see that if it's cold out, you go outside and it's cold and you see how much moisture you leave, you lose when you exhale. That happens all of the time, you just happen to see it because it's cold enough. So that's going to be in a normal situation. But your body's going to adapt to whatever situation you put it in. So let's say you consume twice as much fluid. I used to drink a ton of water when I was in college. So if I'm drinking a whole much more water than my body needs, then you'll see urine production would go up. Or how about on the flip side, if you have diarrhea. So the water losses from feces is usually only 150 or 200 milliliters. But what if you have diarrhea? You're going to be losing way more fluid, which is why it's so important to protect anyone that has diarrhea from dehydration. Whether it's drinking fluid or getting fluid intravenously. This is also why the elderly and infants are so much more at risk when it comes to dehydration because they can't afford to lose a bunch of fluid from diarrhea or other examples. And then you see that skin's on there and sweat. So skin would be the insensible perspiration, the insensible water loss. The moisture leaving your skin right now, even though you're not hot and it's not humid, those kind of things. Sweating is going to be the actual sweating to cool your body down by sweat evaporation if you're overheating. So you hopefully see how these numbers are going to change a whole bunch. So that's why I never tell anyone you should drink 1200 milliliters of fluid. Because if you're a roofer in Texas or someone where it's hot and humid and you're producing liters of sweat, not 100 milliliters, then you better drink a whole lot more water. Well, let's say you're exercising. I tell athletes that are exercising, weigh yourself before you train and after. And for every pound you lose, you should drink at least two to four cups of water because you have to make up for the extra water losses and sweat. So this is the basics of fluid balance, but just keep this in mind. This is a textbook scenario where none of these factors are at play. But this is not gospel. This fluid intake number can change based on a lot of factors, including how much water is in the food you're eating, everything else. Okay? All right, so that's going to be how you balance your fluid, your water gains with your water losses. That's how you reach this fluid balance state that's super important to keep you alive. I hope this helps. Have a wonderful day. Be blessed.