Posted on: June 23, 2017 at 11:51 am
Last updated: September 21, 2017 at 4:20 pm

This amazing guest post was written by Dr. Sarah Brewer, a licensed Medical Doctor, a Registered Nutritionist, a Registered Nutritional Therapist! Check out her website here!

10: What happens to your body after you quit caffeine?

Do you need a cup of coffee to help you wake and get going in the morning? Do you also feel the need for a regular caffeine fix throughout the day?

While one or two cups of coffee a day are unlikely to cause harm, if you regularly consume more than 400 mg caffeine (equivalent to around three cups of strong filter coffee) on a daily basis, you probably have a caffeine addiction.

Caffeine is addictive

Caffeine is a stimulant ‘enabler’ that blocks adenosine receptors in the brain. This increases alertness and affects other brain chemicals to decrease the perception of effort and fatigue. So far, so good.


But your brain adapts to a regular caffeine intake so that the number of adenosine receptors increases. This leads to a build-up of tolerance known as caffeine dependence syndrome. At the same time, the number of brain receptors that respond to other stimulant neurotransmitters may decrease as they are less needed.

The end result is that if you suddenly stop ‘using’ caffeine, your adenosine receptors are deprived of their usual caffeine ‘fix’, and your other coping mechanisms are unable to adapt quickly enough to prevent symptoms of withdrawal such as headache, irritability, fatigue, and lethargy.

The ‘bad’ effects of caffeine

As well as leading to dependence, caffeine mimics the effects of stress in the body, increasing your heart rate and causing palpitations in excess. This may explain why some deaths have been attributed to excessive intakes of caffeinated energy drinks.

Caffeine acts as a diuretic and, in excess, may contribute to dehydration and tension headache. It’s also possible that the effects of caffeine may deplete your adrenal glands so they are less able to respond to stress, although some researchers argue that adrenal fatigue is a myth.

Blood pressure: Caffeine can also cause your blood pressure to rise – in some cases by as much as 10/8 mmHg – either by constricting some blood vessels, or by blocking blood vessel dilation (researchers aren’t sure exactly which). The effect is temporary and usually lasts 30 to 60 minutes, even in people who don’t have high blood pressure. If you have hypertension and are caffeine sensitive (see how to assess this here), then cutting back on caffeine could improve your blood pressure control.   

Diabetes: Another adverse effect of caffeine is that it can decrease insulin sensitivity and increase blood glucose levels in people with type 2 diabetes.  Having said that, black tea also contain antioxidant polyphenols which appear to protect against diabetes, so as with most things in life, moderation is key.

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Iron absorption: Caffeine reduces the absorption of dietary iron by as much as 40% if ingested within an hour of eating so if you take a vitamin or mineral supplement, it is best not to wash it down with tea, coffee, or other caffeinated drinks.

Pregnancy: A high caffeine intake during pregnancy may increase the risk of miscarriage, still birth, preterm delivery and low birth weight. It’s therefore wise to limit your intake of caffeine to no more than 200mg during pregnancy.

Interestingly, many women go off coffee or tea during pregnancy, especially during the first three months which may be a natural, protective instinct. I went from loving coffee to hating the taste almost overnight – before I even knew I was pregnant!

The ‘good’ effects of caffeine

It’s not all bad news for caffeinated drinks. Drinking a moderate amount of coffee is associated with a lower risk of hardening and furring up of the arteries, and regular consumption appears to reduce the risk of developing liver cancer by as much as 40% compared with no consumption. Drinking coffee can even help you lose weight by speeding fat burning and the generation of heat.


Data from twenty studies looking for links between coffee consumption and total mortality, involving almost 974,000 people, suggests that people who drank two or more cups of coffee per day were, on average, 14% less likely to die during the study follow-up periods than those who drank little if any coffee.

Similar beneficial effects were found for tea in studies involving over 856,000 people. Those who drank three cups of tea per day were 24% less likely to die from any medical cause during the study durations, compared with non-tea drinkers.

Overall, it seems that the good effects associated with sensible intakes of tea and coffee outweigh the bad – but excess caffeine is definitely harmful.

Guidelines suggest that single doses of caffeine up to 200 mg are safe, and that habitual intakes of up to 400mg caffeine per day should have no consequences for healthy adults. Intakes about this level ‘could be damaging’ to health. Women who are pregnant or breastfeeding should limit their intake to no more than 200mg caffeine a day.

How much caffeine are you getting?

Caffeine is naturally found in coffee, black and green teas, chocolate and even some herbal tea blends (check labels). Caffeine is also added to some soft drinks such as cola, and to many over-the-counter medicines designed to treat headaches and colds.

High strength caffeine tablets are available to help people stay awake (eg during shiftwork) or to increase alertness when studying for exams. Caffeine gum is also used by athletes for more rapid absorption to boost their performance.


The US FDA is currently investigating the trend for adding caffeine to a growing number of products, however, amidst safety concerns – especially among children and adolescents.     

The amount of caffeine in a drink of tea or coffee varies widely, depending on how the drink is prepared, how long it is left to brew and, of course, on the size of your cup or mug.  Typical caffeine ‘doses’ are as follows:

  • 60ml espresso provides around 80mg caffeine
  • 125ml cup of instant coffee provides 65mg caffeine
  • 125ml cup of filtered coffee contains 85mg caffeine.
  • 150ml cup of tea provides 32mg caffeine
  • 250ml standard can of energy drink provides around 80mg of caffeine (check labels)
  • 330ml can of cola provides around 40mg (check labels).

There’s between 25mg and 50mg caffeine in a 50g bar of dark chocolate and around 10mg caffeine in a 50g bar of milk chocolate.

If you consume more than 400mg caffeine per day you may have a caffeine addiction – cut back slowly to avoid withdrawal symptoms.

  How to cut back on caffeine without going ‘cold turkey’

Aim to cut back on caffeine slowly rather than suddenly. A good weaning program is to reduce your intake by half a cup of coffee or other caffeinated drink every day or so. For example, if you usually have five mugs a day, have 4 and a half mugs on the first day, four mugs on the second or third day and so on. If you start to develop withdrawal symptoms then cut back more slowly.

  • Make your drinks less strong by brewing them for a shorter length of time or adding less granules/tea leaves.
  • Swap caffeinated drinks for decaffeinated brands of tea, coffee, and carbonated drinks.
  • Swap one cup of tea per day for an herbal blend such as soothing chamomile or rooibos.
  • Take an adaptogen herbal supplement such as Rhodiola (mountain ginseng) which can improve alertness, stamina and sleep quality, while helping to counteract fatigue, irritability and headache.

What happens when you ‘quit’ caffeine?

After successfully reducing a high intake of caffeine, you will feel more energised and sleep better. You will feel less irritable, think more clearly, and feel better able to cope with the stresses of everyday life. You may even lose weight by lowering your intake of sweetened drinks and soda – but don’t replace them with sugar-laden alternatives. Sweetness can be addictive too!

Dr. Sarah Brewer
Dr. Sarah Brewer, MSc (Nutr Med), MA (Cantab), MB, BChir, RNutr, MBANT, CNHC, FRSM, is a medical nutritionist, nutritional therapist and the author of over 60 popular health books.

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