drinking a gallon of water a day to lose weight

Drinking a Gallon of Water a Day to Lose Weight: Necessary or Not?

If you have ever had a health goal of wanting to lose some weight, you’ve probably heard something about how drinking water can help. But where did the trend of ‘drinking a gallon of water a day to lose weight’ come from? And does it actually work? We’re going to tackle these questions today!

The Start of the Drinking a Gallon of Water a Day to Lose Weight Trend

This trend of trying to drink a gallon of water a day can be found in many blog posts and all over YouTube and other social media sites. But where did it originate?

water challenge search

Drinking a gallon of water a day to lose weight is also known as the ‘30 Day Water Challenge’. Some companies, blogs, influencers, etc. have actually changed this challenge to be a goal of consuming 64 ounces of water per day, instead of the 128 fluid ounces in one gallon.

Some programs have even changed the rules of this challenge to be swapping all your daily beverages for water (coffee, tea, soda, happy hour drinks, etc.). Regardless, this trend started as a challenge of some kind to get people to drink more water.

Why Our Bodies Need Water

Why did the trend become “drinking a gallon of water to lose weight” instead of something else? It’s because our bodies need water to function.

Water is everywhere in our body! It shows up in every organ, in between cells and even inside each cell. Water amounts vary depending on if it’s a male or female’s body. In a woman’s body, 50-55% of it is water and is up to 60% for men (1).

The percentage of water in a body will decrease with a decreased amount of lean body mass (1). Therefore, athletes tend to have higher amounts of water in their body, while women and older adults tend to have lower amounts (1).

We need to consume water daily because we lose water daily. The water is lost through our sweat, breath, urine and fecal matter. Our daily water requirements may also go up if we have a fever, are experiencing vomiting or diarrhea, are more physically active or are living in a warmer climate.

Benefits of Drinking Water

The reason this trend became so popular is because of the potential benefits from participating. If an influencer or blogger tries this challenge, they usually share the benefits they experienced. Some of the results noted include:

  • Weight loss
  • Decreased bloating
  • Hydrated skin
  • Improved digestion
  • Consistent bowel movements
  • Increased trips to the bathroom
  • Less headaches

Other than the results noted from bloggers and YouTubers, there are other benefits to drinking more water. Benefits of drinking water include prevention of constipation, cushioning our joints and regulating body temperature and blood pressure (2).

Although more research is needed, it has also been noted that drinking more water may help decrease the risk of developing kidney stones (3). Furthermore, higher water intake may help decrease the occurrence of urinary tract infections (UTIs) and bladder infections (3).

Additionally, one review noted that being chronically, mildly dehydrated may put individuals at a higher risk of developing diabetes, obesity, cardiovascular disease, and Alzheimer’s disease (4).

Can drinking water help achieve weight loss?

One major reason why the drinking a gallon of water a day challenge became so popular is for the possible weight loss. 

An increase in water consumption is thought to help by increasing metabolism and having an overall decrease in daily caloric intake. Human studies have found a decrease in body weight with an increase in water consumption in children and adults of all weight categories (normal, overweight and obese) (4).

It has been noted that drinking 500 milliliters or about two cups of water 30-minutes before a meal has resulted in overall decreased calorie intake and increased weight loss (4,5). Another study found that drinking 500 milliliters increased their energy expenditure or calories burned by 24% over the course of an hour (6). 

In the end, drinking water before a meal may help decrease your daily calorie intake and have a slight bump in your metabolism. Plus, increased water intake can provide the other various health benefits noted above, too!

Is drinking a gallon of water a day what’s needed for weight loss?

The drinking a gallon of water a day to lose weight challenge does not work for everyone because every human body is going to have a different water requirement. A person’s activity level and body size will affect their water requirement (3).

The environment that person lives in and the season or temperature can also affect their water needs (3). Additionally, the amount that person sweats, the diet they consume, their current health status and if they are pregnant or not can affect their water needs (3). 

According to Harvard Health Publishing, a general rule for generally healthy people is to consume four to six cups of water each day (2). However, the U.S. National Academies of Sciences, Engineering, and Medicine determined an adequate fluid intake for males and females were 15.5 cups (3.7 liters) and 11.5 cups (2.7 liters), respectively (7).

Determining Hydration

Adequate hydration can be determined through self assessment of your urine and thirst. If your urine is colorless or light yellow, you’re probably consuming adequate fluids. Additionally, if you are normally not thirsty, you’re probably consuming adequate fluids, too (7).

Too much water?

It is important to note that it is possible to consume too much water. Specifically, if you have certain health conditions like, thyroid disease or problems with your heart, liver or kidneys (2).

There are also medications that can retain or hold on to excess water. So, if you’re on one of these kinds of medications, you could potentially have too much water. Medications that fall into this category include (2):

  • Non-steroidal anti-inflammatory drugs (NSAIDs)
  • Some antidepressants
  • Opiate pain medications

In 2007, a woman passed away after participating in a water drinking competition from water intoxication. Water intoxication is also known as over-hydration, hyponatremia, and water poisoning. 

Water intoxication is a rare condition. It occurs when sodium becomes dangerously low in the bloodstream. It is essential to catch water intoxication early on, to prevent severe consequences like seizures, coma and even death (8). Early symptoms include confusion, disorientation, nausea and vomiting (8).

Sources of Water

If you are someone who does not enjoy drinking water, you’re in luck. Daily water intake does not have to come from only drinking water. We also get water from eating food and drinking other beverages, too.

High water containing food and drinks (and water content percentage) include (9):

  • Lettuce (96%)
  • Cucumber (95%)
  • Celery (95%)
  • Coconut water (95%)
  • Zucchini (94%)
  • Tomatoes (94%)
  • Watermelon (92%)
  • Bell peppers (92%)
  • Cauliflower (92%)
  • Cabbage (92%)
  • Broths and soups (92%)
  • Strawberries (91%)
  • Skim milk (91%)
  • Cantaloupe (90%)
  • Peaches (89%)
  • Oranges (88%)
  • Grapefruit (88%)
  • Plain yogurt (88%)
  • Cottage cheese (80%)

Tips to Drink More Water

Here are some ideas to help you drink more water throughout the day:

  • Carry a water bottle with you at all times
  • Eat more foods with high water content
  • Have water with each meal
  • Drink water through a straw (many people find this to be very helpful)
  • Know your water preference: hot, room temperature or ice cold


There may be some benefit to drinking water to lose weight, like slight bump in metabolism and decreasing overall daily calorie intake. However, drinking a gallon of water a day to lose weight might not be necessary.

Every person’s body is going to require different daily water needs. Self monitoring your urine and thirst can help determine if water needs have been met. 

Additionally, water provides the body with many benefits and may even prevent against disease with proper hydration! To stay properly hydrated, drink water and other beverages and eat foods with high water content.

If weight loss is the goal, water may only help slightly. Check out my blog, 5 Simple Health Tips for Weight Loss, for additional tips other than the incorporation of more water. 

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