How much water should I drink to lose weight?

How much water should I drink to lose weight?

Does drinking more water aid weight loss? How do you know if you’re drinking enough? A Registered Dietitian explains. 

We’ve all heard about the age-old rule to drink eight glasses of water per day to stay healthy.

But does that goal change if you want to lose weight? Do those juice cleanses and detox drinks for weight loss work? And, does water help you lose weight?

Read on to have these questions answered and more. Find out how much water to drink in a day to lose weight, achieving proper hydration balance and ways to stay hydrated.

How much water should I drink to lose weight?

The answer to the question, “How much water should I drink to lose weight?” can be a little more complex than you might think. Many factors determine how much water to drink a day to lose weight, including your age, sex, activity level and life stage.

For optimal health, the Institute of Medicine recommends consuming at least the adequate intake (AI) of total water.  Total water refers to all water from food and beverages. AI refers to an average level consumed daily by a healthy population.

 For adult women in different life stages, the daily AI values for total water are:

  • 19 years or older: 91 ounces or 11.5 cups
  • Pregnant women: 101 ounces or 12.5 cups
  • Breastfeeding (lactating) women: 128.5 ounces or 16 cups

For adult men, the AI values are:

  • 19 years or older: 125 ounces or 15.5 cups

According to the Institute of Medicine, 81% of the total water intake came from drinking water and beverages, while the remainder came from food.1 This means that women need to drink at least 9 cups of water while men need to drink 12.6 cups of water — which is much greater than the eight glasses rule!

Some additional factors that may increase your water needs include:

  • Regular physical activity
  • Hot weather
  • Higher elevation
  • Loss of bodily fluids due to illness

 You may also need more water depending on your body weight, but there is no evidence to support a significant increase.

Does water help you lose weight?

So, does water help you lose weight? Yes! However, there is currently no evidence to support how much more water intake is recommended for weight loss.

Fun fact: The act of drinking water can increase the number of calories you burn in a day and increase your metabolism. One randomized clinical trial found that women who increased water intake over time lost weight, even without other interventions.

Another study found that drinking water before meals may help reduce calorie intake at meals. This is likely because you’ll feel fuller when it’s time to eat. However, more studies are needed to understand how much water to drink a day to lose weight.

If you’re a soda drinker, swapping the sugary drink for water could give you a major weight loss boost! In a randomized controlled trial, individuals who substituted caloric drinks with noncaloric drinks for six months saw an average weight loss of 2% to 2.5%. This may be because water contains zero calories compared to sodas. Even with this simple change, you may be able to see modest weight loss over time!

Overall, in addition to drinking water to lose weight, you’ll still need to keep smart portions in mind, eat nutrient-dense food and incorporate regular physical activity to see results.

Can I drink too little or too much water?

Achieving the right hydration balance can be tricky!

Overhydration is rare in most cases. Since healthy individuals can get rid of excess water and maintain water balance, there is no Tolerable Upper Intake Level established for water.1 This is different from other nutrients where toxicity could be a health concern. However, acute water toxicity is possible when rapid amounts of fluids are consumed that exceed the kidney’s natural rate of getting rid of water!

Dehydration is a more severe concern and can cause symptoms such as thirst, dizziness and fatigue.  Between 2011 and 2014, American adults drank an average of 39 ounces of water on a given day, which is much lower than the recommended AI.

Plus, you can be dehydrated even if you drink the AI! We lose water through sweat and urine. So if you are exercising rigorously, moving around in hot temperatures or sitting in a sauna, be sure to have water on hand to replenish any fluids lost.

 One way to check whether you’re getting enough fluids is to assess your urine color.[9] If your urine is consistently a dark yellow color, you may be dehydrated. On the other hand, if your urine has no color, you may consider cutting back on your intake as you may be overhydrated.

Tips to stay hydrated

Now that you know how much water to drink a day to lose weight and how to achieve proper hydration balance, try some of these tips to help you stay on track!

  • Eat fruits and veggies that are higher in water content.

Fruits such as cantaloupe, strawberries, watermelon, grapes, oranges, pears, and pineapples contain lots of water. And don’t forget your veggies too! Celery, cabbage, carrots, avocados, steamed broccoli, roasted squash, lettuce, and spinach are also high in water content. Avoid detox drinks for weight loss

There are many juice cleanses and drinks out there that promise results. In reality, your liver naturally performs detoxification, so you don’t need any special detox drinks for weight loss or your overall health!

  • Upgrade your water bottle

If you want to level up your hydration game, look for a refillable water bottle that provides at least 48 to 64 ounces of water to keep you on track. Carry it with you throughout the day!

  • Add fruits to your water

Lemon water for weight loss may not be a magic solution, but it can make drinking water more fun and help you drink more of it! Try mixing up infused waters like strawberry basil, pineapple mint and cucumber lemon water for weight loss.

  • Listen to your body and check for any signs of dehydration.

Your body will tell you when you are thirsty.


By Chrissy Arsenault, MBA, RDN, LD

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