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Dangerous Side Effects of Eating Too Many Bananas, According to Science

Several bananas a day won't keep the doctors away.
FACT CHECKED BY Kiersten Hickman

When you want to eat healthy, packing in as much fruit into your diet seems like a smart move. According to the Mayo Clinic, a wide variety of fruit contains a ton of fiber, keeping you full through the day and staves off cravings. While fruit in moderation can do some wondrous things for anyone's overall health, overconsumption can lead to a world of problems. High levels of naturally occurring sugar make fruit particularly tricky to navigate and eating too many bananas stand out as a particularly dangerous fruit.

While you might assume all bananas come with equal health benefits and risks, you have to factor in levels of ripeness, varieties of bananas, and more before you can jump to any health conclusions. While bananas in moderation can help deliver key vitamins and minerals, overeating can land you in a world of hurt.

Find out what dangerous side effects lurk under the surface of a banana's healthy public image, and for more healthy tips, be sure to check out our list of The 7 Healthiest Foods to Eat Right Now.

You may gain weight.

Pick bananas grocery shelf

You might believe that bananas' fiber content could help you stay full and lose weight, but if you overeat these fruits, say goodbye to any weight loss goals.

According to Penn Medicine, bananas come packed with considerable amounts of carbohydrates and calories, and when eaten in moderation, can potentially help you lose some weight. When eaten in excess, the opposite couldn't hold more true. According to Cleveland Clinic, the higher amount of sugar found in bananas encourages weight gain, and if you plan on eating a ton of this fruit, expect to see your waistline gain a few inches.

For a slimming diet, hold back on downing too many bananas in order to keep to your weight loss goals.

Your blood sugar will spike.

Banana slices bowl

While those of us with diabetes can have a banana every now and then, eating too many can pose some serious health problems. According to the University of Sydney, an overripe banana's glycemic index (GI) clocks in at 62, pushing it into a moderate GI position. According to a study published through the U.S. National Library of Medicine, anyone who wants to watch their blood sugar needs to stay away from large amounts of food and drinks that fall into moderate or high GI levels. High blood sugar in those of us who can't properly regulate insulin levels can result in diabetic comas and even death, making this fruit a particularly deadly option to overeat.

If you love eating bananas but need to keep your blood sugar levels consistent, make sure to go easy, or at least switch to starchier, less ripe bananas that clock in with a low GI level.

To learn even more about the effects of banana consumption, check out these 11 Side Effects of Eating Bananas Every Day.

You may develop hyperkalemia.


Everyone has heard that bananas provide a great source of potassium, but even a great nutrient in the wrong quantities can do some real damage. If you really love eating bananas, you can develop hyperkalemia, a condition that impairs the function of nerve and muscle cells, landing you in the hospital. According to the USDA, the fruit has 358 milligrams of potassium, and according to the Cleveland Clinic, anyone who pursues a high-potassium diet can fall prey to this side effect.

To keep your health safe, limit your banana consumption, or else you might face some serious potassium-related problems down the line.

You may experience tooth decay.

Man peeling banana to eat

When you indulge in sugary fruits, you can easily risk your dental health. According to the Orlando Sentinel, studies have shown that bananas can do more damage to your teeth than chocolate and sugary gum. When these figures only account for moderate banana consumption, imagine the damage overeating bananas can do to your mouth!

Make your teeth and your dentist happy and avoid overindulging in too many of these sugary fruits next time the craving strikes. Instead, why not concentrate on one of these 25 Foods You Had No Idea Are Good for Your Teeth?

You may experience constipation.

banana slices

According to Makerere University, bananas have a considerable amount of tannic acid stored inside each serving. While this chemical won't do much in small doses, anyone who loves to eat several bananas in one sitting might find a dangerous side effect waiting for them. According to a study published in the journal of Microbial Ecology in Health and Disease, high levels of ingested tannic acid can cause some serious constipation.

While everyone might have experienced constipation in some form, chronic constipation can do terrible damage on our GI tract and can warrant a trip to the doctor. Avoid this seemingly benign effect and put down the bananas!

You may have migraines.

banana cut up
Eiliv-Sonas Aceron / Unsplash

Nothing can derail a perfect, productive day like suddenly doubling over in pain from a sudden-onset migraine. Science has proven that certain chemicals and nutrients can trigger this medical condition, and unfortunately, bananas carry one of these harmful compounds. According to a study published through the U.S. National Library of Medicine, the chemical tyramine has been proven to affect the ways in which migraines develop, and unfortunately, bananas contain a ton of this chemical. Don't risk crippling yourself with the pain of a migraine if you can avoid it and limit your banana consumption to avoid any unnecessary pain.

Here's What Happens To Your Body When You Eat a Banana Every Day.

Erich Barganier
Erich Barganier is a health and food writer. Read more about Erich
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