How Drinking Water Helps You Lose Fat

Our bodies only work perfectly under very specific conditions…

Outside of those optimum conditions, the processes that allow us to survive and function optimally, begin to suffer.


  • get too hot or cold (hyperthermia/hypothermia)

  • lack of oxygen (hypoxia)

  • have too much/not enough sugar in our blood (hyper/hypoglycaemia)

  • don’t get enough sleep

  • eat too much/not enough of individual nutrients (toxicity/weight gain/malnutrition)

Your body is pretty good at maintaining these correct levels in most situations.

But, in some cases, you have to take deliberate action to maintain them…

For example… staying hydrated, by drinking enough water throughout the day.

EVERY cell in your body (and therefore EVERY function in your body) relies on an adequate water supply.

So obviously you need to maintain the minimum level of hydration, just to survive.

But achieving that minimum does not necessarily mean that you are functioning at your best

And we want to thrive, not merely survive.

Here are the ways that dehydration may increase fat gain...

Directly Causes Fat Gain

Even mild dehydration (which is water loss of 2%, compared to optimal levels) will affect your body in many different ways…

One of the end results of chronic dehydration… is fat gain.

When you set a fitness goal, it’s easy to direct all of your focus towards exercise and diet. Ultimately, these are the factors that appear to create the greatest results, and also the factors that get the most attention from P.Ts, the media etc.

However, even the best fitness & diet plans could be ruined by dehydration...

Metabolism & Lipolysis: Your metabolic rate describes the total amount of energy that you ‘burn off’ every day. That includes the calories you burn during exercise, but also the energy that you naturally use throughout the day – breathing, repairing muscles, supporting your posture etc. Every cell in the body requires energy to perform its function (your body contains TRILLIONS of individual cells).

Lipolysis is the ‘proper name’ for the breakdown of fat cells in the body.

Chronic, mild dehydration, is thought to slow down both the rate of lipolysis (breakdown of fat) and cell metabolism…

  • dehydration reduces cell volume and insulin sensitivity

  • dehydration negatively affects mitochondria function

  • dehydration reduces blood volume, reducing the supply of proteins and other compounds to the cells.

This inevitably leads to an increased level of fat storage and lower rate of fat burning.

So... before taking any other factors into account (your exercise, diet etc), you are already counter-acting the benefits your fitness & diet plan by increasing fat storage.

If you believe that;

  • you are following the 'correct' workout plan for your goals

  • you are following the correct nutrition strategy

  • and you are still not seeing the fat loss results that you would expect...

... dehydration could be one of the big reasons why!

Waist Size

Energy & Lethargy

Dehydration will also cause you to feel lethargic.

There might be many reasons why you skip your workouts.

But feeling low on energy in the hour beforehand is definitely not going to help you get yourself going.

Water is involved in every chemical process, in every cell in the body. So guess what happens when there’s a shortage of that water… these process don’t occur as effectively as their supposed to. And of course, many of these processes are responsible for your energy levels (literally, as well as your mental perception of “feeling tired or energetic”).

During workouts: On top of that general sense of fatigue, if you do manage to get your workout done… it will feel significantly harder than it needs to if you’re not hydrated. Among those chemical process that are affected, are those that produce muscle contractions, those that literally produce energy for your working muscles, and those that remove waste products (eg. lactic acid) from your body.

So, your strength is impaired… you are not going to lift as much weight as you would have done if you were hydrated.

And, without removing those waste products, you will bring on the physical symptoms of fatigue much quicker... less reps, less distance, slower speeds etc...

You’ll also ‘thicken’ your blood. This further reduces the ability of your body to remove those waste products… again fatigue will set in much earlier. Your blood is also less able to provide nutrients to the muscles, reducing the ability of those muscles to function optimally...

Reduced blood flow means;

  • Less oxygen

  • Less carbohydrate/glucose

  • Less electrolytes (Sodium, potassium etc)

Without these, muscle function is reduced and you feel significantly more fatigued, earlier in the workout, affecting your end result.

Your level of hydration during exercise plays another crucial role… temperature control.

Obviously, exercise will cause your body temperature to rise, and as a result you will sweat. This response helps to cool your body as the sweat evaporates, taking excess heat with it. Secondly, water that remains stored inside the body is able to absorb heat relatively effectively without your overall body temperature rising above it’s optimum levels.

But of course, you then have two potential problems to consider…

  • you’re losing water from the body

  • you may not have been hydrated adequately in the first place

So without drinking enough water before the workout, and/or not replacing it well enough during the workout, you risk overheating.

Mild overheating is simply going to make you feel extremely uncomfortable. At best, this will be a distraction (remember your physical performance/ability has probably already deteriorated by this point). Sooner or later, the discomfort will force you to slow down, or stop. Workout ruined!

Pouring Water
By failing to hydrate before exercise, and/or failing to rehydrate during that exercise, you severely restrict the quality and quantity of training that you can achieve. Obviously, your results will then reflect that reduced workout capacity.

Effects On Nutrition

Increased Appetite: Again, dehydration has an effect on every cell in your body. As cells need adequate hydration in order to produce energy, dehydration will result in a lack of energy. This causes further problems down the line. When the energy production of those cells is down-regulated, signals are sent to the brain, letting you know that you are short on energy.

Unfortunately, it is easy for your brain to jump to the wrong conclusion...

Rather than specifically identifying a lack of water, you may feel inexplicably hungry instead. This may partly explain your “need” for dessert/snacks shortly after eating what should have been adequate food at mealtime.

If you are aiming to restrict calories to a pre-determined target, this can be a nightmare, as over time, it's going to be extremely difficult to ignore those perceived cravings. “Willpower” is a finite resource, and sooner or later, if you are constantly exposed to perceived hunger, you WILL give in.

Plus dehydration affects your judgement...

Decision making: Dehydration is known to negatively affect your ability to make good decisions...

More than 3/4 of your brain is water. So, as you can imagine, it is affected significantly by dehydration.

Lack of concentration and increased irritability, combined with the skewed appetite mentioned previously, will inevitability affect your judgement... specifically when it comes to choosing the "good" foods to eat, as opposed to simply eating whichever foods you happen to crave at that time...


You’ve got a choice between ordering a pizza for dinner, or spending 30 minutes in the kitchen preparing a meal…

  • you feel tired

  • you’re in a bad mood

  • you feel hot

  • you’re hungry


9 times out of 10, you’re getting the pizza. Afterwards, you know you made the wrong choice. But your decision making was compromised by dehydration.

That's probably going to result in excess calories and a deviation from the nutrients that your nutrition plan was designed to provide.

Glass of Water
Drink water before meals. Not only will your body be better equiped to digest & metabolise food, the boost to cognitive function also means you'll be more likely to make the 'right' food choices. Meaning you are more likely to adhere to your diet plan.

Hormonal Effects

Research has shown that dehydration can lead to a rise in the hormone cortisol.

Cortisol is commonly known as “the stress hormone”.

While cortisol isn’t harmful as such, it’s purpose is supposed to be short lived (eg a short term spike in the morning helps to wake you up, and is also released as part of the ‘fight or flight’ response to danger).

Among the side-effects of chronically elevated cortisol, is the release, and eventual build-up of glucose (sugar) in the blood.

After eating, and digesting food, your body will normally release insulin to remove glucose from your blood and move it to wherever it is needed (storage in the muscles, liver etc). By causing a long-term situation where glucose is lingering in your bloodstream, long-term cortisol production can cause the body to become insulin resistant. This means that your body becomes generally less able to remove sugar from the blood, and is therefore a potential pre-cursor to diabetes.

This does not mean that dehydration is a direct cause of diabetes. And it does not mean that drinking more water is the solution to diabetes.

However, from a fat loss point of view, it is absolutely in your best interests, to maintain a healthy level of glucose in your blood and to avoid developing insulin resistance. While complicated, the likely end result of increased insulin resistance... is increased fat storage.

Avoiding insulin resistance and diabetes is more complicated than simply drinking more water. However, that doesn't mean that you should dismiss this added benefit of staying hydrated...

So, remain consistent with your daily water intake... as well as the benefits mentioned previously, you may be able to reduce the release of the 'stress hormone' cortisol. And in turn, further reduce the risk of excessive fat gain.

Reminder: 'Weight' Loss & 'Fat' Loss Are Different Things

Ironically, a side effect of many ‘weight loss’ programmes/diets is the relatively rapid loss of water from the body.

Water is stored alongside your stored carbohydrates (at a ratio of 3-4 parts water, to 1 part glycogen/carbohydrate). By restricting carb intake, your body depletes it’s stores of glycogen, and the associated water is also lost.

This is why ‘low carb’ diets APPEAR to be effective at achieving quick weight loss.

They cause significant water loss.

Basic weighing scales will tell you that you ‘lost weight’.

You did..

But not the kind you were hoping for.

And of course when you inevitably reintroduce carbs to your diet, you store the extra water again… and your scales report ‘weight gain’.

Remember, weight loss and fat loss are NOT the same thing.