You know that dehydration is bad. But how so in specific terms? Let us count the ways.
1. Dehydration can make you slow.
Endurance performance has been to shown to suffer when you lose as little as 2% of your body weight. That’s 3 pounds if you weigh 150, which is not an abnormal loss via sweat over the course of an hour-or-longer workout. As you become dehydrated, the amount of blood your heart pumps with each beat decreases. As a result, less oxygen-rich blood goes to your working muscles, and you have to work harder to maintain a given intensity level (or you have to slow to maintain the same effort level). This cascade of events is hastened on warm days, when your body sends more blood to your skin to remove heat from your body.
2. Dehydration can make you weak.
It’s not only your aerobic performance that can be hurt by dehydration. Several studies have found that even mild dehydration can decrease muscular strength and power, especially in the high-weight, low-rep workouts that many busy people do for resistance training. One culprit here is dehydration leading to higher temps within your muscle cells, which inhibits the enzyme activity that contributes to anaerobic energy production.
3. Dehydration can make you hungry.
Many dietitians advise people trying to lose or control their weight to make sure they’re always properly hydrated. The reason? When you’re dehydrated, what you might perceive as appetite can be thirst. So you start munching, and keep munching, getting the food’s water content, but also getting potentially unwanted calories. Better approach: Precede all meals with fluids and more accurately gauge your appetite.
4. Dehydration can make you stupid.
Studies have found that even mild dehydration, such as 1.5% of your body weight, can significantly affect your mental capacity. Like all your other body parts, your brain needs water to function properly. Without it, cognitive traits such as concentration, short-term memory and mathematical accuracy begin to suffer. If you work out before work, or during your lunch break, good hydration is key to being your best at the office.
5. Dehydration can make you unproductive.
The above examples have to do with short-term effects of dehydration. Here we’re talking the big picture. It’s distressingly easy to get chronically dehydrated, especially when you’re active outdoors in warm weather. You might not notice a little bit of dehydration, such as less than 1% of your body weight, on any one day. But when this happens day after day after day, the cumulative effect can be insidious. You might feel like you’re always dragging, or irritable, or depressed, or have digestive problems, or all of the above. The gist is that you’re not your best you. What’s worse, you’re likely to worry that something serious is wrong with you, when all you really need to do is drink up.