Simple Answers to Medical Questions

Can Drinking A Lot of Water Cause Weight Gain or Loss?

When it comes to weight management fads, there is often misleading and conflicting reports especially on the Internet. Water consumption is one such case. In this article we look at how water consumption can affect your weight management goals. We are not focusing on fads like the 7 day water diet. Our focus is on regular and relatively normal water consumption during the course of a day, everyday. The question in most people’s minds is whether drinking a lot of water can cause you to lose weight or gain weight.

How much of water for weight change?

Firstly it is important to consider what exactly you may consider as being too much of water. Just a few years back it was thought that drinking 1.5 liters (about 50 oz) was the optimal water intake for an adult. This is incorrect. An adult male should be consuming between 2.5 liters to 3 liters of water a day whereas adult females need between 2 to 2.5 liters daily. This varies by body weight, environmental temperature and level of activity in a day. It will also change if a woman is pregnant or breastfeeding.

So instead of just focusing on 8 glasses of water in a day, you should more correctly be drinking at LEAST eight 8oz glasses of water a day which will equate to about 2 liters (approximately 67 ounces). Remember that you will be getting about 20% of your water needs from the food you eat. While tea, coffee and cola may also contribute to daily water intake, the caffeine in these beverages acts like a diuretic thereby causing you to lose water.

Does water cause weight gain?

Water may have almost zero calories but it does have mass. Fortunately the kidneys will process the water ensuring that any excess water is passed out in the urine, if it has not been lost with the stool, through perspiration or as water vapor from the lungs. In order for you to retain water, you would most likely have some underlying medical problem usually relating to kidney function and blood electrolyte levels. Drinking excessive amounts of water could also be a problem but you would have to drastically exceed the 3 liter (100 ounce) mark to retain the water, which is unlikely to occur in most people.

With moderate water consumption between 2 to 3 liters of water per day (65 to 100 ounces), you will NOT retain the water and not gin weight. However, this is relative. If you were previously in a state of dehydration and your body mass was lower than what it should be, increasing your water intake will restore natural hydration levels and you may find that your body weight increases moderately. This is not abnormal or excessive weight gain. This is the body weight which you should normally have been but was not due to living in a dehydrated state.

To answer the question about whether water causes excessive weight gain, the answer is no. If you are healthy, your kidney will excrete excess water but retain the amount of water that is normal for your body.

Does water cause weight loss?

Water may contribute to some degree of weight loss but not for the reasons that you may think. Water does not have any specific chemicals that raises the metabolism, impairs fat absorption from the gut or suppresses appetite – the key effects of weight loss compounds. However, water can indirectly have these effects and may therefore reduce weight gain rather than promoting weight loss. Once again it depends on the quantity of water consumed in a day and how often it is consumed.

  • Water contributes to bulk in the stomach and drinking sufficient water before or even during a meal may reduce the amount of food that you eat. Since food contains the calories that you need for energy and fat accumulation, water indirectly reduces your calorie intake albeit moderately.
  • Water improves the movement of food and wastes through your bowels. By reducing the bowel transit time, your body may absorb less fat than it would with slower movement. Furthermore water helps you expel the wastes that can accumulate in the bowels and contribute to overall body weight.
  • Water counteracts the state of mild dehydration that has become commonplace in modern life. It is a medium used for most body process and has been shown to help the body’s overall metabolism maintain a normal level. Water does not boost the metabolism above the norm but can still prevent weight gain through a lower than normal metabolic rate.
  • Water helps restore your energy levels and mood as people who are dehydrated tend to be tired and even feel slightly down emotionally. By doing so, it increases a person’s ability and desire to be more physically active and decreases the tendency to snack in order to increase energy levels and improve mood.

To sum up, drinking enough water in a day can help with preventing weight gain although it will not directly cause weight loss. While there may be fears of conditions like hyponatremia (low blood sodium levels) from excessive water intake, this is very unlikely to occur in a healthy person who is drinking a normal amount of water in a day.

External references to this topic :

  1. Can drinking lots of water help you lose weight. CNN
  2. Water-induced thermogenesis. JCEM
  3. Replacing caloric beverages with water. The American Journal of Clinical Nutrition

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