How Is Fructose Bad for You?

Medically Reviewed on 7/11/2022
is fructose bad
A high fructose diet, such as consuming more than 100 grams per day, can cause negative effects on the body, which can lead to metabolic disorders and weight gain.

According to the majority of evidence, a small amount of fructose (between 0 and 80 grams per day) does not cause any significant health hazards. Furthermore, a meta-analysis, based on pure fructose excluding high fructose corn syrup (HFCS), even showed benefits such as improved HbA1c levels when fructose intake was less than 90 grams.

However, there is no doubt that fructose is bad for you when consumed in large amounts, which may cause negative effects on the body, leading to metabolic disorders and weight gain. According to a meta-analysis, more than 100 grams of fructose per day causes these negative effects.

  • HFCS is a processed form of fructose generated from corn that is used as a sweetener in various processed foods and sodas in the United States.
  • These sweeteners are considered unhealthy because they contain a high amount of fructose, and even just one serving of food containing HFCS may exceed your daily limit of fructose intake.
  • Soft drinks sweetened with this sort of sugar are rich in calories, and studies have suggested that fructose is linked to obesity.

Why is fructose bad for you?

Fructose is a simple sugar. It is often present in baked goods, syrups, and desserts.

When people consume a diet that is rich in calories and processed foods that contain a lot of high-fructose corn syrup, the liver begins converting fructose into fat. A lot of medical professionals think that consuming too much fructose is one of the main causes of metabolic diseases.

Many studies employed quantities of fructose (60 percent of a diet) that are significantly greater than what most people would typically consume and reported that it may cause:

  • Obesity. Physical activity, stress, and genetics are just a few factors that can increase the chance of being obese, but consuming too much sugar might have an impact. Likely, fructose does not activate the brain regions that regulate appetite. However, more research is required.
  • Liver issues. Nonalcoholic fatty liver is more likely if a person consumes too much fructose. An excessive amount of fat accumulated in the liver cells causes cellular inflammation. Overaccumulation of fat can result in nonalcoholic steatohepatitis, liver scarring, and liver damage.
  • High triglycerides. Fructose can increase blood triglycerides according to studies. Triglycerides play a role in conditions including pancreatitis and arteriosclerosis, which is the hardening of artery walls (inflammation of the pancreas). A diet containing 17 percent of fructose for six weeks caused triglycerides to rise by 32 percent according to research.
  • Increased uric acid. Additionally, fructose can increase uric acid production. Gout, a painful form of arthritis, can be brought on by an excess of uric acid.
  • Type II diabetes. The pancreas produces the hormone insulin to control blood sugar levels. If a person has type II diabetes, their body cannot use insulin as it should (insulin resistance), causing increased blood sugars. Even moderate levels of fructose and sucrose affected insulin sensitivity of cells in a small trial that involved healthy adults drinking sweetened beverages for three weeks.

Fruit is safe, but fructose from added sugars is not

Fruits are substantial foods with low-calorie content and a lot of fiber. They are good sources of antioxidants. In comparison to other sources of sugar, fruit generally provides very little dietary fructose.


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What is fructose?

Fructose, also known as fruit sugar, is a type of sugar naturally found in all types of fruits, table sugar (sucrose), some vegetables, and honey.

Fruits may contain fructose, but they are low in calories and have a lot of fiber. Even then, consuming fruits doesn’t harm the body the way high fructose corn syrup (HFCS) does because, comparatively, fruits contain fewer amounts of it.

Fructose, like glucose, is a simple carbohydrate (called monosaccharides). However, fructose is structurally different from glucose, so the body reacts to them differently and metabolizes them differently. Fructose also has different chemical properties compared with glucose. Fructose is metabolized by the liver, so the liver may get overloaded with it after excess consumption of high-fructose foods. The liver converts fructose into fat, which increases fat deposits in the body.

Fructose and glucose are sources of energy for the body. They combine to form table sugar or sucrose. A major part of fructose is burned to produce energy for the body. Some of it is converted to glucose for further metabolism, while other portions are converted to lactate and excreted by the liver. A very small percentage is converted to fats and gets deposited in the body.

What is high-fructose corn syrup?

High-fructose corn syrup is frequently added to processed goods. Corn, sugar beets, and sugar cane are the main sources of fructose utilized in high-fructose corn syrup.

  • When compared to conventional corn syrup, high-fructose corn syrup is produced from cornstarch and contains more of this simple sugar than glucose. The sweetness of the three sugars is greatest in fructose.
  • The human body digests and absorbs it in various ways. Because monosaccharides are simple sugars, cells can utilize them as fuel without having to break them down.

What are high fructose fruits?

Table 1: Fruits high in fructose chart
Fruit Serving size Grams of fructose
Figs, dried 1 cup 23.0
Apricots, dried 1 cup 16.4
Mango 1/2 medium 16.2
Grapes, seedless (green or red) 1 cup 12.4
Raisins 1/4 cup 12.3
Pear 1 medium 11.8
Watermelon 1/16 medium melon 11.3
Persimmon 1 medium 10.6
Apple (composite) 1 medium 9.5

What foods are naturally high in fructose?

The following are some examples of natural foods high in fructose:

  • Apples
  • Apple juice
  • Pears
  • Prunes
  • Dry figs
  • Sorghum
  • Asparagus
  • Jerusalem artichokes
  • Chicory roots
  • Leeks
  • Onions
  • Caramel
  • Licorice
  • Molasses
  • Agave syrup
  • Honey

Like glucose, fructose enters the circulation through the small intestine and is immediately absorbed.

According to medical experts, fructose has the least effect on blood sugar levels. It seems to have no immediate impact on insulin levels although it raises blood sugar levels much more gradually than glucose does.


According to the USDA, there is no difference between a “portion” and a “serving.” See Answer

What are the harmful effects of fructose on the body?

According to one study, consuming 255 grams of fructose per day increased liver fat and reduced insulin sensitivity. However, similar results were obtained when 255 grams of plain glucose was consumed, showing that it's not just fructose that's the problem.

Excess fructose consumption in the form of added sugars has many negative effects on the body, which include:

  • Resistance to hunger hormones:
    • Ghrelin is a hunger hormone that provokes appetite, and leptin is a hormone that inhibits hunger, regulates energy, and reduces fat storage.
    • Excess fructose increases ghrelin levels leading to increased appetite and causes resistance to leptin hormone disturbing body fat regulation.
    • Either way, the person feels the urge to eat more, resulting in weight gain and increased fat deposits.
    • Deposition of fat in the liver leads to non-alcoholic fatty liver disease (NAFLD).
  • Addiction to sweets:
    • It is believed that fructose may lead to addiction to sweet food.
    • Glucose activates the reward circuits in the brain, increasing sugar cravings throughout the day.
  • Increased risk of weight gain and obesity:
    • It is believed that excess intake of fructose may increase the risk of weight gain.
    • It stimulates hunger and fat deposition in the body.
  • Insulin resistance:
    • Consuming foods rich in fructose causes insulin resistance.
    • This increases the risk of diabetes and heart diseases.
    • Therefore, people with diabetes should avoid foods that contain a high amount of added fructose.
  • Increase in bad cholesterol:
    • It is known that consuming excess fructose-containing foods can cause lipid imbalance in the blood.
    • It increases the levels of bad cholesterol (low-density lipoprotein [LDL] and very-low-density lipoprotein [VLDL] cholesterol) and triglycerides that are linked to an increased risk of heart disease and stroke.
  • Increase in uric acid:
    • Consumption of excess fructose may increase the levels of uric acid in the blood, leading to gout, heart diseases, kidney diseases, and high blood pressure.

To avoid bad effects on the body, you should eat fresh and natural meals. Negative effects of fructose apply to a diet that is high in calories and sugar. Natural sugars present in fruits and vegetables are not included.

It's worth mentioning that not all of this has been proven in scientific studies. However, the evidence remains, and additional research will be conducted in the coming years to present a fuller picture.


Many fruits and vegetables naturally contain fructose, which people can consume as part of a balanced, nutrient-rich diet.

According to the U.S. Food and Drug Administration, “There is little evidence to conclude that the substance is less safe than other sugars that are similar to it, such as sucrose and honey, but it nevertheless advises limiting all added sugars.”

People consume additional calories that may lead to weight gain when they consume a lot of high fructose foods or beverages, such as those with added sugar.

Because a person does not require this sugar to survive, there is no recommended minimum or maximum fructose intake. Fructose is a sweetener that manufacturers use although it offers no nourishment.

Doctors recommend consuming fresh, whole foods and steering clear of foods with added sugars.

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Medically Reviewed on 7/11/2022
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Rizkalla SW. Health implications of fructose consumption: A review of recent data. Nutr Metab (Lond). 2010 Nov 4;7:82.