From brain fog to overeating – what happens when you don’t have enough water

STAYING hydrated is important and close to 60 per cent of our bodies are made up of H2O.

The NHS states that water is a great drink as not only does it quench your thirst but it also contains no sugars that damage teeth.

It’s recommended that you drink 6-8 cups of fluid a day, with low-fat milk, sugar-free drinks and tea and coffee all contributing towards that.

Shockingly, around 62 per cent of Brits say they don’t drink water at all, even though it fuels our cells and keeps our mind and body functioning.

But what actually happens if we don’t get enough water and how will it affect your body?

Here experts reveal the five ways a lack of H2O can have an impact on your health.

1. Brain fog

Your brain is about 80 per cent water, so by keeping your body hydrated you are keeping your brain sharp, both in the short term and long term, Dr Martin Kinsella founder of says.

He explained that not drinking enough water can have a real impact on your cognitive functions.

Dr Kinsella explained: “If you are dehydrated, your reactions may be slower, you may feel foggier than usual, and it may affect your concentration. It’s best to always keep a glass of water in front of you, and sip throughout the day to keep you sharp. 

“It’s also worth noting that cognitive responses naturally become slower as we age, this is down to hormonal changes, and again, it is crucial that you keep hydrated.

“Hormonal changes can be difficult, and leave some unpleasant side effects, such as insomnia, night sweats and hot flashes.

“Keeping hydrated will keep the sweats at bay, and keep your melatonin levels in sync; which will help you to stay asleep.”

If you suspect you have a hormonal imbalance, Dr Kinsella says you should see your GP who will be able to tailor treatment around your individual needs.

2. Weight gain

Dr Charlotte Norton, Medical Director at the explains that when you don’t drink enough water, your body can’t produce the energy it needs to function. In turn this will make you crave sugary snacks. 

She said: “Interestingly, dehydration can be one of the leading causes of weight gain. When your body is dehydrated, you lack energy and begin to feel tired. 

“To replenish that energy, you reach for sugary or fatty snacks, because your body tells you that’s what it wants. Ultimately, this leads to weight gain. 

“It’s a good idea to drink a glass of water before you sit down for a meal, this will give you a better sense of your hunger cues and appetite, meaning you may consume fewer calories.”

Dr Norton also explained how dehydration can cause water retention – which is where our body fights to hold on to as much fluid as possible to survive.

She added: “This is a natural response, but it will cause your water weight to increase. In the long run, this can lead to localised swelling, pain and discomfort when fluid becomes trapped within body tissue.”

3. Headaches

Many people who are dehydrated will end up with a headache and this is usually because there is an imbalance of fluid and electrolytes in the body, Dr Norton said.

She explained: “Dehydration could also cause you to become irritable; this is down to the loss of blood flow to the brain, and fatigue. 

“You should always keep a glass of water with you throughout the day, and try to avoid drinking too much soda, hot drinks, or alcohol.

“Whilst these are all liquids, they can dehydrate your body further. This is most likely down to sugar content that stops the body absorbing the water it needs.

“Alcohol has a direct effect on the body, making you need the bathroom more often, thus loosing fluid”, Dr Norton said.

4. Low energy

Water helps keep the mind and body balanced and a lack of it can cause your energy to plummet, Dr Kinsella said.

He explained: “Our body needs water to survive – lots of it. If our cells aren’t adequately hydrated they cannot produce the energy we need to keep going, causing us to feel fatigued.

“As soon as you wake up, start your day with a big glass of water. Not only will it help you wake up, but it also flushes out toxins and helps to cleanse your bowels – it will also stimulate your red blood cells to populate faster and boost your energy levels.”

5. Skin issues

Skipping or lowering your water intake could cause your skin to dry out and water is essential to maintaining healthy skin, Lou Sommereux, Clinical Director at says.

She said: “If you are dehydrated, your skin may become dry, itchy, and dull looking. In turn, your complexion may appear uneven and fine lines and wrinkles may become more noticeable.

“You should aim to drink around two litres of water per day to keep your body, and skin hydrated.

“Water helps to stimulate collagen production within the body, and collagen is essential for skin health. Collagen helps the skin to retain moisture and elasticity, without it the skin may begin to appear saggy.”