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  • Writer's pictureBianca Amoruso-Wennerby

Coffee when waking up and on an empty stomach: What we need to know about our beloved ritual.

For many people, starting the day without a cup of coffee may seem unthinkable. The morning ritual of drinking a cup of black coffee has become so ingrained in our culture that we rarely stop to think about the possible consequences this habit could have on our health. But science has something to say on the subject, especially if you consume coffee on an empty stomach when you wake up!

What are the effects of coffee on an empty stomach?

Gastric Acidity: Coffee stimulates the secretion of gastric acid. Drinking coffee on an empty stomach can lead to a temporary increase in stomach acidity, predisposing to problems such as gastritis or ulcers.

Insulin Surges: Coffee can lead to insulin spikes, especially if consumed without food. These swings can affect your metabolism and increase the risk of insulin resistance.

Dehydration: Coffee is diuretic. If consumed first thing in the morning, it can lead to dehydration if fluid is not adequately replenished. It would be a good and healthy habit to drink one or two glasses of water in the morning before introducing coffee to integrate body fluids and as a "defensive" act before introducing caffeine. Many people drink coffee and forget to drink water believing that coffee acts as a necessary and hydrating liquid.

Neurotransmitter Imbalance: Coffee stimulates the production of cortisol, the so-called "stress hormone". Consumed upon waking, it can alter natural circadian rhythms.

Loss of appetite: Coffee can lead to a temporary or prolonged loss of appetite, if consumed a lot during the day.

I want to focus on this last point as it is particularly close to my heart and is often the subject of discussion between me and avid coffee drinkers.

What is the link between coffee consumption and lack of appetite?

Many of those who don't eat breakfast in the morning start the day with a cup of coffee on a completely empty stomach, and maybe... even with a cigarette (but that's another story). This - they say - stimulates their intestines and is sufficient as a "breakfast". “I'm not really hungry in the morning, my stomach is closed, I wouldn't be able to eat anything”, this is the phrase I hear most often.

Let's see what the science says!

Coffee and Appetite

An interesting point concerns the relationship between coffee and appetite. It has been observed that coffee, being a bitter substance, can actually "close" the stomach. This is a concept rooted in naturopathy: bitter substances are often used to stimulate digestion, but they can also suppress the appetite if consumed before meals.

If we look at the evolutionary function of bitter substances, they often acted as signals of toxicity. Therefore, our body may react by reducing appetite as a defense mechanism. From a nutritional point of view, consuming coffee before a nutritious breakfast can therefore lead to skipping or reducing the most important meal of the day!

Furthermore, not eating properly in the morning (which does not mean milk and biscuits, or croissant and cappuccino), means interfering with our metabolism. Breakfast "awakens" our metabolism, giving it the signal to start burning calories. By skipping breakfast, your body may go into a "conservation" mode, reducing the rate at which it burns calories because it doesn't know when it will get its next food intake. If the body feels there is a shortage of food, it may start storing fat as a defense mechanism, since fat is an energy reserve. This can lead to weight gain in the long term.

Eating regularly helps keep blood glucose levels stable. Skipping breakfast can cause blood sugar to spike and dip throughout the day, leading to feelings of tiredness, irritability, and a greater tendency to overeat or choose unhealthy foods later.

Coffe and Insuline

When we drink coffee on an empty stomach, our body releases glucagon, a hormone that increases blood glucose levels. This is because caffeine, acting as a stimulant, causes the body to release this hormone to increase blood glucose levels, preparing it for immediate activity and energy response.

In response, insulin is released to reduce these sugar levels. This hormone in turn is released mainly when blood sugar levels are low, for example in the morning on an empty stomach.

This cycle, if repeated frequently, can lead to insulin resistance, increasing the risk of type 2 diabetes.

Let me explain better and with simple images.

Imagine that your cells are little houses with doors. Insulin is like a key that opens these doors to let in sugar, which is food for your cells.

If we eat too much sugar or drink too much coffee on an empty stomach (which therefore increases blood sugar levels through glucagon), the body finds itself having to produce many keys (insulin) because there is a lot of food to get into the houses. But if we use too many keys too many times, the doors can start to jam and not open easily.

When the doors do not open well, even if we have many keys, food (sugar) cannot enter the houses. This is called "insulin resistance", because the doors resist and do not open easily despite all the keys. And this is not good because our houses (cells) need food to function well and because we let sugar in our circulation.

Then this happens:

  • Without the "gates" open, sugar builds up in the blood. Think of it as a bag of candy that can't find a home to go, so it piles up outside doors.

  • Cells need sugar to produce energy. If they don't get sugar, you may feel tired and without energy, as if you haven't eaten in a long time.

  • If there is too much sugar in the blood for a long time, it can damage certain parts of the body. It's as if the sweets that were left outside the houses started making a mess around.

  • Even if there is a lot of sugar in the blood, the cells think they are hungry because they are not getting the sugar they need. This can make us feel even more hungry and crave sweet food.

  • The body tries to put away excess sugar by converting it into fat. Think of it as the body trying to put extra candy away in special boxes for use later.

That's why it's important for sugar to enter cells: so it can be used for energy and not cause problems by staying outside. Coffee on an empty stomach in the morning "disturbs" and alters natural processes and if it is always consumed in the same way over time it can cause damage.

Insulin Resistance and Diabetes

Insulin resistance is one of the key factors that can lead to type 2 diabetes. Here's how it works, explained simply:

Insulin Resistance: As we have discussed, when cells become resistant to insulin, the "keys" (insulin) struggle to open the "doors" of the cells. This means that blood sugar cannot easily enter cells where it would be used as energy.

Excess Sugar in the Blood: Since sugar cannot enter the cells, it begins to accumulate in the blood. This is what we mean when we say someone has "high blood sugar."

The Pancreas Works Harder: The pancreas is the organ that produces insulin, the "keys". Seeing that sugar does not enter the cells, the pancreas thinks: "Maybe I need to make more keys!" Thus, it begins to produce even more insulin.

Pancreatic Exhaustion: After some time, if insulin resistance continues, the pancreas may become tired. It starts producing less insulin just when the body needs even more to try to get sugar into the cells.

Type 2 Diabetes: When the pancreas cannot produce enough insulin to handle high blood sugar and sugar remains consistently high, type 2 diabetes develops.

Essentially, insulin resistance makes it difficult for sugar to enter cells, causing a buildup of sugar in the blood. If this problem persists over time and is not managed, it can lead to type 2 diabetes.


Coffee, with its aromatic nuances and its energetic appeal, is an inevitable component of the routine of many. However, as with many things in life, how we consume it can make a big difference.

Coffee is rich in antioxidants and bioactive compounds that may help improve brain function, increase metabolism, and reduce the risk of some diseases and some forms of cancer. Furthermore, its moderate stimulating effect helps improve concentration and alertness, making it a precious ally in your daily routine.

However, drunk on an empty stomach, it can interfere with delicate hormonal balances and trigger a series of reactions in the body that may not be ideal for our health. Daily habits, which might seem harmless or even beneficial, can sometimes have unexpected side effects if not done correctly. In many cases, the damage or degenerative processes we fear simply arise from repeated practices and habits without due awareness.

Let's give coffee the respect it deserves: let's consume it with awareness, keeping in mind our general well-being and giving our body the best possible start every day.

To get the most out of your morning coffee, consider accompanying it with a balanced breakfast or, if you prefer, postpone your coffee after eating something.

Health, after all, is found in balance!

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