Water, the fuel for peak performance
Winter's when you worry about putting on weight and give little thought to how much water you drink, but the two are inextricably linked. Mild dehydration alters mood and lowers concentration and energy levels. Sanchita Sharma reports.columns Updated: Oct 27, 2013 01:23 IST
Winter's when you worry about putting on weight and give little thought to how much water you drink, but the two are inextricably linked. Mild dehydration alters mood and lowers concentration and energy levels. It also derails diet and causes weight gain.
Water accounts for roughly 60% of the body's weight. Apart from keeping the brain sharp, it moistens tissues, cushions the joints, regulates body temperature and helps the body absorb nutrients and flush out toxins.
Since the symptoms of mild dehydration (tiredness, difficulty concentrating) mimic those of hunger, people often mistakenly think their body needs food when what it's really asking for is water, reported the Journal of Nutrition.
Fluids also keep weight in check by filling up the stomach and lowering hunger pangs by making you feel satiated. This is the reason why almost all weight-loss plans recommend drinking lots of water through the day, especially before meals.
Even a shortfall of a couple of glasses of fluid can hurt your health. Mild dehydration - defined as 1.5% loss in the body's water volume, which triggers feelings of thirst - affects everyone, from people who work in air-conditioned offices to marathon runners, who lose up to 8% of their body weight each time they compete.
But by then, the adverse effects have already kicked in. Mild dehydration shrinks the brain and makes you dull-witted, particularly in the areas of vigilance and working memory, and makes you fatigued, tense, andanxious even if you're not exerting.
When it comes to mood swings, dehydration shows a gender bias. Women are more affected by adverse mood changes than men, both at rest and during exercise, reported the British Journal of Nutrition in November 2011.
Real dehydration occurs after 2% water loss - water accounts for 60% of body weight - causing headaches, nausea and dizziness.
Telltale signs of chronic dehydration are dry and scaly skin, muscle cramps and constipation. Acute dehydration lowers blood pressure, increases heart rate, makes the eyes appear sunken, and causes lethargy and confusion.
The US Institute of Medicine, an expert panel that set desirable intake levels for water, salt and potassium, has debunked the recommendation to drink eight glasses of water a day and instead, proposed 3 litres (about 12 glasses) a day for men and 2.2 litres (about 9 glasses) for woman.
Fluids, of course, include all the juice, milk, tea and coffee you have, apart from the roughly 20% of the total water intake that you get from the food you eat. For example, many fruits and vegetables, such as watermelon and tomatoes, are 90% or more water by weight.
Most doctors say if you don't have a kidney problem, you should drink as much water as you can, more so if it's hot or you've been active. Dieters and people on long fasts need to drink water frequently, as both conditions cause an electrolyte imbalance and may make the body lose water faster.
Risk of dehydration is high not just in hot, sweaty weather but also in indoor heating and in places at altitudes higher than 8,200 feet (2,500 m), which may trigger rapid breathing and increased urination, both of which use up fluid reserves.
Hydration is particularly important for people over 65 years, pregnant and nursing mothers, and people who have diabetes or an illness that causes fever, vomiting, or diarrhoea. Babies and children are also more susceptible because they are small with low body weight and have a higher turnover of water and electrolytes.
Young children often can't identify the feeling of thirst and forget to drink water, increasing their risk of dehydration.
How much additional fluid you need depends on how much you sweat during exercise, and the duration and type of exercise. Fluid need doubles with strenuous or prolonged physical activity, especially in warm, humid weather, so double intake before, during and after exercise.
An extra 500 ml (two glasses) of water is enough for short bouts of exercise, but intense exercise lasting more than an hour need more fluid intake. During long bouts of intense exercise, opt for a sports drink which contains sodium to replace the sodium lost in sweat.
For a caffeine addict like me, the good news is that though this is diuretic and makes the body lose water, it does not cause dehydration as the effect is fleeting. But it's best to have water within reach whenever you can, especially with and between each meal, and again.
Apart from keeping you alert and happy, it'll also help you survive winters without adding weight.