Does caffiene cause dehydration?

February 23, 2014 BY: LISA

Does caffeine cause dehydration?

It has long been believed that coffee has a diuretic effect on the body- which means that it causes us to urinate more often and therefor contribute to dehydration rather than hydration.

A diuretic agent is one which blocks the reabsorption of sodium (salt) in the kidney. It is a natural occurrence that when salt is passed out in the urine water will follow. So any product that causes more sodium to be passed out (not reabsorbed into the body) will naturally cause increased urination which of course results in more water leaving the body.


New study

A recent study has shown that men who regularly drink coffee could have 4 coffees per day with no effect on hydration levels. We can say from this that it’s highly likely to have the same effect on women, however this study only looked at men.


What’s normal?

Normal turnover of body water in a 70kg adult is 2.5-3 litres per day which is lost in sweating, faeces, through the lungs and in the urine. Where some water comes into the body via food but by far the majority comes in through the fluids we drink.

The amount of water we require in a day is approximately:

  • 2.1 litres for women
  • 2.6 litres for men


Good news

So the good news is that we now know that 3-4 coffees per day will not cause dehydration and does in fact contribute to our daily fluid intake- is there anything else to consider?


Things to consider

If you are trying to lose weight and are having 3-4 all milk coffees such as a late` or cappuccino then you may find this is too many. I often recommend people use these milk coffees as a snack because a glass of milk has a great balance of protein and carbohydrate to help manage hunger as well as the extra calcium which is a nutrient bonus. However having 3- 4 glasses of milk a day may be a bit much if you are trying to lose or maintain your weight.

The other thing is if you are having a number of these all milk coffees then you won’t be hungry for your lunch which may lead you to put it off and then you run a couple of risks:

  1. You will miss lunch but you will get hungry mid-afternoon and end up grabbing a higher fat biscuit/cake/chips or chocolate as a snack to tide you over.
  2. By only having milk coffee you are missing out on other essential nutrients that eating your lunch would hopefully have provided. (depending on what you eat for lunch!)


Take home message

The overall message is: it’s okay to drink coffee but it is best to make up the 2.1-2.6 litres each day with a healthy dose of water. So plan to have water in between your coffees.


Here are five ways to make water easier to drink:

  1. Carry a bottle of water with you always
  2. Have a jug of water on your desk to get through each day
  3. Make a new routine that whenever you get a coffee you get a glass of water to sip on after the coffee.
  4. Avoid sculling water as that will have you running to the toilet and be an inconvenience-the trick is to sip it over a period of time.
  5. Add in some fresh lemon/lime/orange to give your water an interesting twist.


Drink Up!

Lisa APD


All enquiries, Lisa 0413 956 107 Appointments 1300 725 806
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