Feeding the Family: Fluid Intake Recommendations

Hydration is extremely important for humans and animals to stay alive and have all of our biological processes be executed as precisely and efficiently as they are capable of. So today’s post is going to be on some tips and guidelines for proper hydration year round.

First of all, we need to talk about the fact that there is a variance in how thirsty we feel depending on many different factors. The weather, how much salt we are consuming, whether we have trained, or whether we are drinking alcohol all play a role in how thirsty we feel. And just because we don’t feel thirsty doesn’t necessarily mean that our bodies aren’t losing fluids, there is a lag time between the fluid loss and our bodies’ registration of the thirst signal to our brains. For many of us in climate controlled environments most of the day excessive dehydration isn’t a huge concern, but for athletes and people working outside in hot climates, it is a major risk that needs to be discussed. These dehydration problems can get serious very quickly.

So, how much should you be drinking? Well, it definitely depends on your size and your activity level, but there is a starting point we can use as a rule of thumb. Most adults need around three liters(L) of water, which for everyone using the english system is a little less than 1 gallon of water. It doesn't have to be just straight water, other fluids count as fluid intake. Some fluids like sodas and alcohol aren’t very valuable to your system, so I typically don’t count them toward fluid intake, but most other things can be included. I know that sounds like a heck of a lot of water to get down for an average sized person!

Just know that you may get a whole liter of fluids from the food that you eat, taking it down to 2L a day, something that sounds much more manageable. If you’re a larger person, you will still need to be closer to that gallon mark. If you're sick, and especially if you're losing fluid through vomiting or diarrhea, your fluid and electrolyte intake will need to be increased. If it's warm and dry, you may need another few cups of water a day. And if you're exercising a whole heck of a lot you could potentially need up to like six liters of fluid per day, so there are clearly a lot of factors to keep in mind when looking at hydration! If you’re going to begin drinking 3L of water per day, and this is interrupting your life because your going to the bathroom so much, you may want to reduce your fluid intake until you adapt to the higher amount.

Again, just because you're in a comfortable environment does not mean that you're not losing fluid. Everything passes through our skin as it is the main medium between our internal bodies and the external environment. There's a lot of heat and water that gets lost just through your skin.

By no means is keeping up with hydration easy, I know I have trouble with it!. Most of us are in a mild state of dehydration at all times. To keep up with this, I have a water bottle with me at all times, because if I don’t have constant access I will not get enough fluids in. Personally, I like to have a water bottle that is a full liter in size, because I have to fill it up less and will naturally get more water in.

Percentage of body weight is the main measure we look at for the consequences of water loss.. With ½%, there is increased strain on the heart, with 1%, we see a reduction in aerobic endurance. This is why you see athletes in endurance sports are always on top of their hydration levels. At 3% we see reduced muscular endurance while at 4% we see reduced muscular strength, a reduction in motor skills, and heat cramps. At 5% heat exhaustion begins with cramping, fatigue, reduced mental capacity and at 6% we see physical exhaustion, heat stroke, and coma. Once an individual hits 10 to 20% they are probably going to face death. So we want to make sure we're keeping fluids in at all times. Very regular consumption. Most people shouldn’t have an issue with this.

It’s easy to monitor percentage of body weight lost due to exercise: simply weigh yourself before a training session and then again after the session. Those two numbers will tell you how well you are hydrating during the training session.

Now, I mentioned before, there's often a lag between becoming mildly dehydrated and your body's signal to let you know you're actually thirsty. So we tend to not even notice thirst until we've lost 1 to 2% of our body water. As I just mentioned, at this point it is already having some negative effects on our performance. So just as a reminder, this is increased strain on the heart and reduce the aerobic endurance. And beyond that, we start to get into some pretty unpleasant things. Other side effects that can happen outside of just performance implications include headache, fatigue, low blood pressure, dizziness, fainting, nausea, and even rapid heart rate.

The goal here is to simple: always make sure if you're working out in the heat or, your job requires you to be in an extreme environment of some kind (hey, this includes athletes!) that you always have access to fluids and be sure that you're rehydrating regularly. If we do that, then we should be all set and stay out of trouble.

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Fluid is Fluid? A Lesson in Hydration

The weather for the second half of this week around the DC Metro area promises to be a bear! The kind of bear that brings high humidity and high temperatures with it. Yuck-o.

In honor of it really feeling like summer, I've put together a bit of a hydration survival guide (you can take that literally, by the way) for strength and power athletes:

Hydration and Strength:

• A sweat-induced body weight loss of 2% during a training session can result in a significant performance decline. Strength, power, and overall performance will suffer.
• A sweat-induced body weight loss of 4% or more during a training session begins to cause physiologic strain resulting in increased core body temperature, heart rate, and perceived effort.
• Try to stay ahead of trouble by consuming fluids throughout a training session. Rather than simply attempting to replace lost weight via water and sports drinks after the session is over.

• Athletes involved in multiple practices or training sessions in a single day need to take their hydration seriously as a domino effect of declining performance can occur from one training session to the next.

How Much is Enough?

• Depending on training status, fitness level, body size, training intensity, and heat acclimation status, athletes tend to sweat at a rate of 0.5-2.0L per hour (that's liters! 2 liters an hour... let it sink in).
• To prepare to enter a training session well hydrated, consume at least 1L or 34 ounces of fluid the day before exercising AND/OR consume 14-20 ounces 2 hours before training session begins and continuing to ingest fluids throughout session.
• Exercise lasting less than 90-minutes really only warrants water as a sufficient source of hydration.
• Exercise beyond 90-minutes should include a carbohydrate sports beverage to provide both fluid replacement and a fuel source for the working muscles.
• The addition of electrolytes - even though marketing companies will have you believe otherwise - are unnecessary for most strength/power athletes as their diet covers this base. However, when acclimating to extremely hot/humid conditions or if you are in a negative caloric balance, electrolyte addition can be a good idea.
• Consider taking in fluids during practice/training in the same quantity and timing that you will during competition.

• During hot/humid conditions it is a good idea to take your body weight before and after exercise. Then replace each pound lost with 24 ounces of fluid.

What Counts as Fluid?

• Anything that is safe for human consumption has fluid in it and counts towards total daily fluid intake (check out the table below, all those amounts add up). Plus, things like coffee, tea, and *gasp* even soda count, too (counting as fluid is different from what is optimal to consume, by the way).
• Men should take in 128 ounces (3.8L) of fluid each day.
• Women should take in 88 ounces (2.6L) of fluid each day.
• Check out the fluid content of some common foods:

Cucumber (1 large)

10 oz

Watermelon (1 wedge)

9 oz

Asian pear (1 large)

8 oz

Chicken noodle soup (1 cup)

8 oz

Corn (1 cup)

7 oz

Salad (1.5 cups)

7 oz

Lowfat yogurt (1 cup)

6 oz

Lowfat cottage cheese (1 cup)

6 oz

Baked beans (1 cup)

6 oz

Baked potato (1 medium)

5 oz

Brown rice (1 cup)

5 oz

Grapes (1 cup)

5 oz

Apple (1 medium)

4 oz

Oatmeal (1 cup)

4 oz

Orange (1 medium)

4 oz

You'll probably have a tough time staying cool for the rest of the week, but hopefully this helps keep you well hydrated. Good luck!