Contents

Handbook of Nutrition

Preface

Basics

What is a Calorie?
Measuring Nutritional Requirements

Nutrients

Food

Conclusion

What's Next?

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Water

Contents

Functions
Dehydration
Requirements
Everyday calculation
References

Water is an essential element for life to the best of human knowledge. All biological processes required to sustain life happens in the presence of water. Water fills every space inside the cells and between them in our body and corresponds to 60% of our body weight.

Functions

There is a common adage that an individual can survive without food for 7 days, but cannot survive more than 3 days without water. For the human body to function as a system, there must be water present in the body.

Water is the primary solvent in your body helping it to assimilate nutrients like vitamins, minerals, amino acids, glucose, etc. Water also assists in the transportation of these nutrients and oxygen to cells and in the elimination of toxins from the body.

Water is also the critical element to cool your body down — remember sweating on a hot day or during a physically intense activity? It is possible because of the presence of water.

Dehydration

Dehydration is the lack of enough water in your body and is classified as acute and chronic dehydration. Acute dehydration results from an intense loss of water in a short period of time (a sport game or workout session) and chronic dehydration results from long term inadequate intake of fluids.

Medically speaking, dehydration is defined as 1% or greater loss of body weight resulting from fluid losses. Because every system in the body uses water, dehydration results in an impaired functioning of the entire physiological system including salivary dysfunction, flushed skin, blurred vision and vision blackouts, physical weakness, heat cramps, stones in urinary stones, stress, degraded mental performance, emotional instability, heat exhaustion and finally death.

Studies have found a co-relation between low fluid intake and urinary tract, colon and breast cancer. Drinking enough water reduces the risks of these cancers.

Requirements

Water can be sourced from plain drinking water, beverages and food. Your water requirements are largely based on the loss of water in your body, which is influenced by your lifestyle and the climate you live in. So there is no one amount of water prescribed for all.

However, based on statistical studies, here is a table of water requirement as per the National Institute of Nutrition, India.

	Stage	Total Water	From Food	From Beverages
Man	Sedentary work	3.15 L	1.1 L	2.05 L
	Moderate work	4.05 L	1.25 L	2.8 L
	Heavy work	5.2 L	1.45 L	3.75 L
Woman	Sedentary work	2.5 L	1 L	1.5 L
	Moderate work	3.2 L	1.1 L	2.1 L
	Heavy work	4.1 L	1.25 L	2.85 L
	Pregnant	3.7 L	1.1 L	2.6L
	Lactating	4.1 L	1.25 L	2.85 L
Children	1-3 years	1.65 L	800 ml	850 ml
	4-6 years	2.05 L	850 ml	1.25 L
	7-9 years	2.55 L	1 L	1.55 L
Boys	10-12 years	3.3 L	1.2 L	2.1 L
	13-15 years	4.2 L	1.3 L	2.9 L
	16-18 years	4.5 L	1.5 L	3 L
Girls	10-12 years	3.05 L	1.25 L	1.8 L
	13-15 years	3.5 L	1.55 L	1.95 L
	16-18 years	3.7 L	1.35 L	2.35 L

Everyday calculation

In most cases, your thirst signals that your body needs water and the color of urine can tell you whether you had enough of it. Consume water whenever you get thirsty and consume it enough to quench your thirst. When engaging in physical intensive activity, your thirst will increase. Your body is loosing water at a faster rate and thus requires faster replenishment.

Verify that you are hydrated by the quantity of urine and the colour of it. If you do not have the sensation to urinate every 2 to 3 hours whatever work you are engaged in, you are not drinking enough water. If your urine is not clear but yellow in colour, you aren't drinking enough water.

References

Water: an essential but overlooked nutrient, Susan Kleiner.
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Nutrient requirements for Indians, 2020. ICMR-NIS.
View resource