December 18th, 2013
A litre of water, or 1,000 cc in volume, weighs a kilogram or 1,000 grams. On the outside, our body consists of bones, flesh, skin and hair. Inside, more than half is water. This is why we need water to keep the system going well.
When we are dehydrated, the body will feel tired, sleepy and inactive. The brains will also function poorly. Brain surgeons know well that the brains and water are closely related because when an operation is done at the brain, if there is not enough water, the brain will shrink. If there is too much water, it will swell like a sponge dipped in water.
This is only one example of how our internal organs rely heavily on fluids. Not only those, but also our skin, which will obviously show how much or little water has been drunk that day. Too little water makes the skin dry and wrinkly, while plentiful water makes the skin radiant and plump.
Water intake does not only come from drinking water or other beverages, but also from eating food which contains various amount of water. For example, watermelon has a lot of water content, while dried shredded pork has just a little. Runny soup has more water than fried food. In general, our body gets water from food at about 500-700 ml per day, which is the same amount as the water we lose from sweating (with or without actual sweat being visible) and breathing.
At least 1.5 litre should be drunk every day, as it will be mostly excreted by urine and also in bowel movement. Constipation means there is not enough water. Runny bowel movement means we lose more water.
Fluids are very important for our body because our cells are mostly made of water. In order for cells to function properly, there needs to be sufficient of water. Moreover, water helps remove toxins from the body through the kidneys. People with kidney failure will have toxin build-up in the body and the skin will turn dark until the person receives kidney dialysis.
How the water flows in our body is closely related to the amount of salt. Salt in this case means sodium chloride which can be found in salty food or strongly flavoured food. Salt is also plenty in dried and fermented food and snacks. This is because salt helps the food keep longer without being spoiled.
Salt causes the body to retain water. If we consume too much salt, we will be extra thirsty. Excess amount of salt will result the kidneys to overwork and salt might not be flushed out of the body effectively. The body will be swollen especially around the feet and shins. The excess salt that remains in the body causes water retention in the blood vessels, which in turn causes high blood pressure. People with high blood pressure could experience symptoms after consuming too much salt in food, even if the food does not taste salty.
Water and salt is cause and effect. If the kidneys work well, there is a balance between water and salt in the body and the blood sodium level will be stable.
As we grow older, the kidneys age as well, and their capability drops. People with high blood pressure should be under strict low-sodium diet and may need to take anti-diuretic medication to keep blood pressure at bay. If the water-sodium balance is not in check, it would affect the brain, muscles, your heart, and your bowel. The person could experience muscle twitching, nausea, vomiting, unconsciousness or even seizure.
Heart disease patients, especially those with heart failure history, must keep body fluids level in check all the time. They will be asked to watch their diet and limit sodium intake. If the body does not receive excess salt, the kidneys are able to flush it out properly. Limiting sodium is more important than the amount of water drunk.
Sodium limitation means more than water limitation, but it is not easy to do. In most food, there is sodium, especially in meat. When a doctor takes care of a heart failure patient who has to limit sodium intake, water in the body must also be monitored. The patient must be weighed regularly, and a kilogram of extra body weight is considered as a litre of excess water in your body.
Usually, our body weight does not fluctuate much during the day. The maximum change is half a kilogram. If we get on the scale at the same time of day every day, the weight should not change more than that. If it does, it means water is retained in the body (or if it reduces by more than 500 grams, it could be dehydration). If you normally weigh 60 kg and suddenly you weigh 60.5 the next day, it is still normal. If it is 61.5 kg, it means there is 1.5 litre of excess water in your body.
By “the same time of day every day” I do not mean it by the clock, as in 8am every day. This is based on your daily activity, such as before breakfast, after bowel movement and urination. Sometimes it is hard to stick to the routine, so I normally recommend my patients to get on the scale before breakfast after urination, to eliminate the breakfast factor and urine factor.
Weight and water are closely linked as we can see in athletes who need to maintain certain weight to be qualified in their range. They have to get on the scale wearing the lightest clothes and after urination. If their weight is still too much, they will have to exercise in warm clothes to get rid of excess water by sweating. Some even take anti-diuretic medicine to reduce water, which is the quickest way to lose weight.
If your weight fluctuates within a few days, or even hours, it is due to the water level. If you lose a kilo in a day, or a week, usually the lost weight is due to water loss, not fat. Sometimes people on a diet are all happy they lose as much as a kilo in just a week, but in fact the fat is all there as before.
A patient of mine has narrowed artery and high cholesterol. He was rather chubby as well. He exercised like I recommended, but he could not fight his cravings for food. Every time he came to see me, he was stressed out because his weight kept increasing. Sometimes he tried not to drink water before he saw me, went to the bathroom, and exercised before he got on the scale. After that he had to rush to find something to eat because he was starving.
Doing so, he could lower his weight to a certain extent (just a couple of kilos), but it’s not his real weight. Last time I saw him, he asked to get on the scale in private so he could remove all his clothes.
Prof Nithi Mahanonda is consultant cardiologist and interventionist, Perfect Heart Institute.
ข้อคิดเห็นทั้งหมดนี้เป็นความคิดเห็นส่วนบุคคลของผู้อ่าน ไม่เกี่ยวข้องกับเจ้าของเว็บไซต์แต่อย่างใด โปรดแสดงความเห็นด้วยความสุภาพ ถ้าเป็นครั้งแรกที่คุณโพสต์แสดงความเห็น อาจจะมีการคัดกรองเนื้อหาได้ การแสดงความคิดเห็นควรอยู่ในประเด็น ห้ามโจมตีใส่ร้ายบุคคลอื่น หรือทำลิงค์ไปยังเว็บไซต์ที่มีเนื้อหาไม่เกี่ยวข้องกัน ผู้ดูแลเว็บไซต์สามารถแก้ไขหรือลบความคิดเห็นได้ทุกกรณี
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