60% of our body is water. We all know that staying hydrated is essential, but just how vital is it, what are the risks if we don’t, and how do we hydrate correctly?
Water is an essential component of every living organism. 60% of an adult man’s body is water, less in an adult woman because of higher body fat, but more water in babies and kids. It is necessary for survival since we cannot live without water for long. Water is vital for many of the bodily processes that keep us alive.
For example, more than half of our blood is water, circulating to transport oxygen and nutrients to every cell in the body and carrying carbon dioxide and metabolic waste away. Water also supports our blood pressure and redistributes heat to maintain normal body temperature around 37°C.
Water is a vital part of our body. Two-thirds of our body’s water is inside our cells (intracellular), and one-third is outside. Extracellular water is divided into intravascular (water in blood) and interstitial water (between blood and cells), where oxygen, nutrients and body waste exchange occur.
You are fully hydrated when you have adequate water in your body and dehydrated when you do not. Dehydration occurs due to insufficient water intake or excessive fluid loss. The water depletion starts in the extracellular fluid and progresses to the intercellular water. This results in the shrinkage of cells, compromising their metabolic activities.
Digestion, absorption, and cell function
You chew your food and break it down into smaller elements. As a solvent, water dissolves large molecules and breaks them down into smaller ones. The digestive enzymes, largely water, continue breaking down food into its primary molecules – carbohydrates into glucose, fats into fatty acids and proteins into amino acids. Minerals and vitamins are released during the process.
Only these primary food elements – glucose, fatty acids, amino acids, vitamins, and minerals – can pass through the gut lining, enter the blood, and be distributed to fuel and support our cells’ activities.
At the cellular level, our body generates adequate energy and makes building blocks necessary for growth and repair. The process involves a series of chemical reactions. Water creates a medium where the chemical reactions occur, allowing the body to deliver different bodily functions.
Without water, the body cannot work, turn sugar and fat into energy, or make these building blocks for bodily maintenance.
Does drinking water help weight loss?
Drinking water fills your gut with zero-calorie fluid so that you eat fewer calories. Replacing sugary drinks with water can also lower calorie intake. Water is a natural appetite suppressant, proven in clinical studies using appetite scores.
Drinking water can settle ghrelin, the hunger hormone. This relieves the hunger that you feel because of an empty stomach.
Increased hydration leads to body weight loss through decreased feeding (eating less) and fat loss through increased Lipolysis. This happens due to an expansion in cell volume, thus enhancing insulin sensitivity. And activate your mitochondria (energy plants) to burn more sugar and fat.
A study of 27 women found that drinking water, or even just the intention to drink water, helped the participants speed up their metabolism, burn more fat, and lose weight.
Drinking water increases your daily energy expenditure. One study accelerated metabolism by 25% for nearly an hour, meaning drinking a few cups regularly will keep your metabolism at peak level all day.
Another study demonstrated that drinking 500ml (2 cups) of water increased the metabolic rate by 30% for 30 to 40 minutes. The overall effect was sustained for more than an hour.
Another study gave 50 overweight girls 500ml of water thrice a day, half an hour before a meal for eight weeks. The study demonstrated positive changes in body weight, body mass index and body composition.
If you go on a diet, in the first week, almost 70% of your weight loss is water released after burning stored sugar (glycogen), usually stored with a lot of water.
How the body regulates hydration
Your total body water is controlled by your water intake and loss of water in urine and sweat. The body keeps water in balance using a sensor in the brain that sends signals to the body. The hypothalamus centre, stretch-sensitive neurones, detect how much water and electrolytes are in the blood and send a message to the pituitary (the master) gland to make more antidiuretic hormone. This then switches off the kidney to produce less urine.
The hypothalamus can also trigger sweating or urination to eliminate excess water.
With significant fluid loss, the hypothalamic sensor instructs the pituitary to produce less antidiuretic hormone, allowing the kidney to conserve water.
Excessive secretion of the anti-diuretic hormone is a common medical problem that often results in too much water in the body. This lowers sodium concentration in the blood, resulting in a serious condition known as hyponatraemia. This is usually treated with strict fluid restriction to less than a litre a day and drugs stimulating the kidneys to rid the body of excess water.
Inappropriate secretion of antidiuretic hormones frequently happens as a side effect of medications, infections, severe stress, or even cancer.
Alcohol suppresses the antidiuretic hormone. Having a few drinks within a short time can result in dehydration.
Caffeine is known to have a diuretic effect: consuming 250mg of caffeine (2 cups) in brewed coffee can cause increased, more frequent, and more urgent urination but does not necessarily lead to dehydration.
Sweet beverages can lead to dehydration. The body gets rid of the huge sugar load in the urine. If a lot of sugar must be eliminated with a large volume of water, this can result in dehydration.
Fluid balance regulation declines with age. For example, activation of the thirst mechanism becomes impaired in the old adult. It is helpful to give the senior citizens adequate water to sip all day and monitor their urine colour and volume.
A very pale yellow to light yellow urine is a sign of good hydration; darker yellow urine is a sign of dehydration. Very dark, brown, or cola-coloured urine indicates severe dehydration and the need for urgent medical attention.
Other risks associated with dehydration
Dehydration makes the blood thicker and the circulation sluggish, increasing the risk of blood clot formation. Blocking a major vessel can result in serious medical conditions, such as heart attack and stroke.
Dehydration increases the risk of deep vein thrombosis (DVT), mainly in the leg or calf. The clot often dislodges and travels to block pulmonary (lung) arteries, causing pulmonary embolism, a potentially life-threatening complication.
Dehydration increases the risk of kidney and gallbladder stones, urinary tract infections and constipation.
How much water do you need to drink?
Your water requirements depend on your physical activities and your living environment. The average person in the UK needs between 2 and 3 litres or eight 250ml glasses of water daily—the need increases in more active people and those living in a hot climate.
Water’s lack of taste often prevents people from drinking enough water, and others are not keen because it makes them visit the toilet frequently. But you can flavour water with lemon, strawberry, and ginger to make it palatable.
Drinking tea, alcohol, coffee, or sugary drinks may not be helpful, as these cause diuresis and can result in dehydration. Drinking too much water all at once can also result in excessive diuresis and perhaps dehydration. The ideal is to sip water regularly throughout the day.
When do you drink water?
Preferably, drink water 30 minutes before or two hours after a meal. Drinking water during or immediately after a meal interferes with digestion. Water dilutes the digestive enzymes and makes them ineffective, resulting in indigestion and tummy cramps.
There is a high prevalence of a chronic state of dehydration in Western countries, through us drinking only caffeinated beverages, tea, coffee, and hot chocolate during the day and alcoholic drinks at night without thinking about rehydration. Compare this with the Mediterranean culture, where every caffeinated or alcoholic beverage is served with a glass of water.
High blood sugar in diabetes, prediabetes or after meals results in excessive urination (polyuria) and thirst (polydipsia). The body gets rid of high sugar levels through the kidneys, pushed out with a high volume of water. If you urinate a lot, this may be a sign of high blood sugar, early diabetes, and the need for adequate fluid hydration.
Stay hydrated and drink a glass of water to hydrate your veins 15 minutes before you visit a phlebotomist unless a fasting blood sample is required. It takes longer for your veins to hydrate when you are dehydrated.
Does it matter if the water is cold or warm?
There is evidence that drinking enough water helps those who intend to lose weight, but the temperature of the water, and whether it is hot or cold, matters little. Cold water can shrink the stomach and interfere with blood supply and the release of digestive enzymes. The resultant indigestion can cause symptoms such as heartburn, bloating and stomach cramps.
Drink water at room temperature. I advise my patients to drink 500ml of water and add a teaspoon of apple cider vinegar and another teaspoon of lemon or lime in the first hour when they wake up. I call it morning hydration, with great benefits to metabolism. ACV improves insulin sensitivity, and lemon and lime increase bile flow and lower cholesterol and body fat.
Drink more water, but not from a plastic bottle.
So, my friends, you can see how vital our hydration is. Water plays a part in many essential bodily functions, and staying hydrated is comparatively straightforward once you get into the right habits. Please share your thoughts and questions by commenting on this piece, and please subscribe to the newsletter so you don’t miss further vital information. Thank you!
References
Increased hydration can be associated with weight loss.
Effect of water-induced thermogenesis on body weight
How does hydration affect Metabolic health?
