How Much Water Should You Drink For Weight Loss?
“How much water should I drink?” is one of the most common questions I receive. The answers you’ll hear will vary. Some people advocate drinking 1 gallon of water per day, others claim that you only need a few glasses. So how much water do you actually need and why does remaining hydrated help weight loss?
Are You Dehydrated?
Without enough water, your body cannot function properly. Sometimes it’s hard to know whether you’re dehydrated. Dizziness, fatigue, dry skin and thirst are all common symptoms of dehydration.
But let’s be honest, it can be hard to tell whether a slight headache is due to a lack of water or simply due to the fact that you’ve been reading my articles for the last 8 hours straight.
The simple way to figure out whether you’re dehydrated is to look at the colour of your urine.
If your urine looks like the second from the left on the diagram below, then you’re fine.
Anything darker than this should be a cause for concern. The solution then is to simply increase your water consumption in proportion to the darkness of the urine.
Perhaps you’re taking a multivitamin and this is making your urine yellow. In this case, simply stop taking it for a few days and continue as normal.
Observe whether your urine is clear throughout the day and if not, adjust accordingly.
4 Reasons Water Works For Weight Loss
Water is important for weight loss and it can be advantageous to be hydrated.
Most underestimate how important water is, but many also overestimate how much we actually need. Here’s how water helps you lose weight more effectively.
1. Water improves athletic performance.
Your muscles are about 80% water. Therefore when you’re adequately hydrated your muscles are going to function better and your athletic performance is going to increase.
Drinking water on your way to the gym isn’t going to help if you’re dehydrated. Your body needs at least an hour or so to absorb it properly.
2. Water Increases Your Metabolism
In a study of overweight women, increasing daily water intake over a 12 month period helped them lose an average of 4.4 pounds (1). This is independent of diet as well as activity.
People’s energy expenditure actually increases by 24-30% within about 10 minutes of drinking water (2).
2. Use Water As A Tool To Eat Less
Our brain often tricks us into thinking we’re hungry when we’re actually thirsty.
Next time you have some cravings try and drink a glass of water. You can drink water 30 minutes before a meal. We all know this works, but it’s important to go back to basics from time to time.
4. Improved Digestion And Bowel Movements
Now this one is tricky. Some studies have shown no difference at all and there isn’t actually as many controlled scientific trials on this as you’d hope.
Most studies which show this relationship are simply showing an association (including variables such as fibre and magnesium), which are both very evidently known to help with bowel movements, as shown in this study (3).
I think the basic takeaway here is that more isn’t necessarily better. You’re not going to turn your water intake into a laxative. In saying that, chances are that remaining hydrated will help in one way or another.
How Much Is Water Too Much?
I once heard this story about an army somewhere in the middle east, on their way back from victory thousands of years ago.
They had no food or water and were severely dehydrated. They finally came across a lake. It was a miracle. They ran to the lake and drank so much water that they all died from water intoxication.
Regardless of whether this story is true or not, the fact remains that it’s possible to actually die from too much water. This happens every year. I’m not saying that it’s common, but it’s more common than you’d think.
The kidneys can only excrete fluid at a set rate. Therefore, too much water in a short period of time creates a large concentration of things like potassium inside cells.
With enough water this causes water to go into the cells to dilute the concentration as well as balance the electrolytes.
Too much and the cells swell, leading to potential death.
Don’t worry about this unless you’re an endurance athlete or have a reason to be drinking a lot of water.
We all have different heights, genetics and weights, etc, which means we all have different requirements for food. Water is no different.
For example, a person eating mainly fruits such as watermelon (which is mostly water), working as a yoga instructor has different requirements compared to an endurance athlete on a ketogenic diet.
Activity level and even the climate of your country will all play a role and thus I think the most accurate test comes back to the colour of your urine rather than “8 glasses of water per day.”
It’s up to you to figure out what is ideal for your body based on your lifestyle.
Does Coffee, Tea And Caffeine In General Dehydrate You?
This is a bit of a controversial topic. I’ll give my opinion on the matter based on the evidence and you can come to your own conclusion.
Too much caffeine is bad because it causes insomnia, anxiety and headaches in many. One study confirmed that coffee caused the greatest diuretic effect (4).
This study looked at coffee and aimed to determine whether it would dehydrate or hydrate people who drank it. The conclusion of the study was that a:
caffeine intake of 6 mg kg−1 in the form of coffee can induce an acute diuretic effect, while 3 mg kg−1 do not disturb the fluid balance in healthy casual coffee drinking adults at rest. (5)
For example, 3mg kg for me would be 2-3 cups of coffee and many more cups of green tea. To be clear I’m not advocating for that much caffeine to be consumed, I’m just applying for the numbers from the study to my own body.
What I disagree with is the idea that coffee and tea actually prevent liquids from contributing to daily net hydration.
Yes, caffeine is a diuretic and there are certain teas which make people urinate more than others. But caffeine is a weak diuretic in the quantity which people consume it, especially with tea.
A 2011 randomised controlled trial looked at how tea consumption affected blood and urine markers of hydration. 21 males consumed four cups of tea, or water and the results showed that there were similar hydration levels resulting from these differences between both groups (6).
You’ll find that when you drink alcohol you pee a lot, that’s because alcohol is a fairly strong diuretic. Caffeine is similar but less strong.
The basic idea is that any dehydration provoked by caffeine from coffee is generally going to be compensated for by the water it is being consumed with. So for a moderate amount of coffee, you have nothing to worry about.
Does this mean you should stop drinking water? Of course not.
Water is the best option, yes, but I think it’s safe to say that drinking most liquids is hydrating, albeit perhaps to a slightly lesser extent, but most certainly not dehydrating.
A simple question to ask is this: If you gave someone tea and another no liquids and stranded them on a desert island, who would die of dehydration first?
Forget about 8 glasses of water per day. Judge your hydration based on the regular colour of your urine.
Water is great for weight loss because it improves athletic performance, increases your metabolism, helps increase satiety, perhaps improves digestion and bowel movements. But remember, it’s not a magic solution.
How much is too much? Well, too much water and you can die, this is true. But don’t worry about that unless you’re an endurance athlete or have a reason for drinking a lot of water in a short period of time.
A moderate consumption of coffee and tea will not dehydrate you.