Is It Bad to Drink Coffee on an Empty Stomach? A Dietitian Separates Fact From Fiction

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Coffee is one of the most widely consumed beverages in the U.S. About 62% of people in the U.S. drink coffee every day, according to the National Coffee Association. And the average daily coffee intake is about 3 cups per day.

Morning is the most common time of day to drink coffee. So you may wonder: Is it safe to drink coffee on an empty stomach?

Here's what you need to know about how coffee can affect your body, and what happens when you drink it on an empty stomach.

What happens to your gut when you drink coffee?

Your digestive system responds in a few ways when you drink coffee:

• Your stomach produces acid to help with digestion.

• Your pancreas and bile ducts release hormones to help break down food.

• Your colon becomes stimulated to contract, which helps you form stools.

• The types of bacteria that live in your gut may change.

Note that all these things happen in your body despite the fact that brewed, black coffee contains almost no macronutrients (carbohydrates, protein, or fat). This means that there isn't anything that your body actually has to digest. However, coffee contains other nutritional components.

These include:

• Caffeine

• Minerals

• Plant compounds called polyphenols

What happens when you drink coffee on an empty stomach?

There isn't a lot of research specifically on drinking coffee on an empty stomach. But studies suggest that when you drink coffee on an empty stomach:

• Caffeine is absorbed more quickly by the gut.

• Caffeine levels in the body are higher than when coffee is consumed after eating.

So, you might feel that kick of caffeine more quickly and more powerfully when you drink coffee first thing in the morning before you've eaten. That may be a good or bad thing, depending on how caffeine makes you feel. Some people feel anxious from too much caffeine, while others like the kick.

But there's no evidence that drinking coffee on an empty stomach is bad for you. Below, we look at some research to see what the science says - and doesn't say - about how coffee affects your body.

Reflux/heartburn

Coffee is naturally acidic. And caffeine relaxes the muscle at the bottom of your throat, which can cause food to reflux back up. So, coffee is believed to be a common trigger for acid reflux and/or heartburn - also known as gastroesophageal reflux (GERD).

But the evidence is mixed. Some studies have found that drinking coffee is associated with a higher chance of having reflux. Other large reviews found no link between coffee and reflux.

The American Society for Gastrointestinal Endoscopy considers coffee a possible "trigger food" for reflux. They suggest keeping a food diary to track your symptoms and see if coffee makes symptoms worse. But they say that if coffee doesn't bother you, it's fine to drink.

Most studies look at drinking coffee with meals or after meals, not on an empty stomach. But, since drinking coffee on an empty stomach means that there's less food to "reflux," it might be even less likely to cause symptoms.

What matters is how your body responds. Keep track of your symptoms. If you feel fine drinking coffee on an empty stomach, it's OK to make that part of your morning ritual.

Ulcers

The caffeine in coffee causes your stomach to release acid. Too much stomach acid can lead to the development of ulcers, sores on the lining of your stomach or small intestine. This is why many people believe that drinking coffee can lead to ulcers.

But research doesn't support this belief. Multiple studies have found that there's no link between drinking coffee and getting ulcers. In fact, according to the American College of Gastroenterology, diet doesn't cause ulcers.

And drinking coffee on an empty stomach wouldn't be expected to increase your chance of having an ulcer. In fact, when you eat food, your stomach produces acid as part of the normal digestive process. So an empty stomach would have even less acid than a stomach with food. This means that drinking coffee on an empty stomach is unlikely to cause ulcers.

Jitters/anxiety

Caffeine is known to contribute to anxiety. Caffeine from coffee is rapidly absorbed into your bloodstream. As mentioned above, caffeine is absorbed even faster if it's consumed without food. This helps explain why consuming coffee on an empty stomach may lead to increased feelings of the "jitters" or other symptoms of anxiety. (Consuming caffeine with food can cause similar symptoms, but usually they won't be as severe.)

For this reason, you may choose to limit your caffeine intake. Or pair it with some food. This will help slow the absorption and reduce possible negative effects.

Exercise performance

When you drink coffee before a workout, it can help you exercise better. Drinking coffee has been shown to improve:

• Muscle strength

• Endurance

• Speed

And research has found that this exercise-boosting effect is even more pronounced if you drink your preworkout coffee on an empty stomach. So if you like to start your day with a workout, grab a cup of coffee first - even before breakfast - to give an extra boost to your exercise.

Diarrhea

You may already know that coffee can help you poop. Coffee sends signals to your gut to increase contractions and help move food along. So it can be a helpful drink to try if you're constipated.

But does coffee cause diarrhea? Some studies suggest it doesn't cause diarrhea in otherwise healthy people. But if you have irritable bowel syndrome (IBS), drinking coffee can make your symptoms worse, and may make you stool too often.

If you're prone to loose stools or diarrhea, pay attention to what happens when you drink coffee - on a full or empty stomach - to see if you should lower your intake.

Malabsorption

Coffee contains antinutrients, including oxalates and tannins. Antinutrients are plant compounds that can block your body from absorbing certain nutrients. So, some people believe that drinking coffee can lead to problems absorbing these nutrients.

It's true that caffeine and antinutrients in coffee together may reduce the body's ability to absorb nutrients, such as calcium, magnesium, and iron. Research suggests that drinking coffee with a meal reduces iron absorption by 24% to 73%.

For most people, this effect will be minimal. But some researchers recommend that for this reason, pregnant people should limit coffee consumption and avoid drinking coffee with meals.

But drinking coffee on an empty stomach specifically should have a minimal effect on nutrient absorption. If no food is consumed with the coffee, there are no nutrients to hamper. So, from a nutrient perspective, it might actually be better to consume coffee on an empty stomach.

Weight gain

There's no evidence that coffee on its own will contribute to weight gain. In fact, caffeine from coffee can actually boost your metabolism. Studies show that consuming caffeine may help promote weight loss and reduce body fat. And it doesn't seem to matter whether the caffeine is consumed on an empty stomach or not.

But the relationship between coffee and weight is complex. Many coffee drinks are loaded with excess calories, fat, and added sugar - all of which can contribute to weight gain. So it's important to try to choose healthy coffee drinks, and drink them as part of a balanced diet.

Changes to gut bacteria

Multiple studies have shown that drinking coffee can affect the types of bacteria in your gut microbiome - the collection of microorganisms living in your digestive tract. But there are trillions of bacteria lining your gut, and scientists are trying to understand them better.

At this point, it's clear that drinking coffee affects your gut's bacteria. What's not clear is whether these changes are positive or not.

Energy levels

Many people drink coffee not just for the taste, but for the energy boost that caffeine can provide. Caffeine increases energy levels and alertness. Depending on the person, blood levels of caffeine can peak between about 15 minutes and 2 hours after it's consumed.

Eating food slows down the rate at which caffeine gets absorbed. So, as mentioned above, drinking coffee on an empty stomach means you'll probably feel that energy boost more quickly and/or in a more pronounced way.

But everyone's body works differently. Other factors, like your weight, also affect how quickly you'll feel that jolt of energy.

When is the best time to drink coffee?

There isn't really a best time to drink coffee for all people. When to drink it will depend on personal preference. Some people can tolerate drinking coffee first thing in the morning without any issues. Other people do better drinking coffee only after they have eaten a meal.

People who deal with sleep issues are better off drinking coffee in the morning and steering clear of it the rest of the day. This is because the stimulating effects of caffeine can last between 2 and 12 hours. The Sleep Foundation recommends avoiding caffeine at least 8 hours before you go to bed. Or, you can try drinking decaffeinated coffee as an alternative.

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