Like it or not, sugar is present in almost everything you eat. From fruit and chocolate to wine and tomato sauce, this sweetener is found in both natural and processed foods, so it can be difficult to sort through the noise and determine which sugars negatively affect your health or offer benefits.

While sugar can be enjoyed in small amounts, experts agree that consuming excess fructose (by way of added sugars) takes a toll on your body and can lead to unwanted side effects. But is weight gain one of them? 

Before exploring if fructose leads to weight gain, let’s first understand what sugar is, if there is a difference between natural and refined sugars, and where fructose fits into that equation.

Understanding sugar

Sugar is a soluble carbohydrate that your body converts into glucose and uses for energy. The two main categories of sugars are monosaccharides (“simple” sugars that consist of one molecule) and disaccharides, which consist of two monosaccharide molecules joined together. There are also different types of sugar (such as dextrose, fructose, galactose, glucose, lactose, maltose, and sucrose) which can be classified as either natural or refined sugars. 

What is fructose?

Fructose is a monosaccharide that is found in many plants–like sugar cane, sugar beets, and corn–and can bond with glucose to create sucrose (table sugar) [

3

]. Interestingly enough, studies have found that fructose has a unique molecular structure that makes it almost two times sweeter than sucrose [

10

]. 

Fructose naturally occurs in fruit, agave syrup, and honey, but it can also be added to processed foods and beverages in the form of high fructose corn syrup (HFCS). Foods with high fructose corn syrup include, but are not limited to, candy, sugary beverages, fast food, baked goods, sauces, bread, jams, jellies, and applesauce.

Fructose vs. glucose

While fructose and glucose are both monosaccharides and come from natural sources, there are a few key differences between the two.  

• Glucose: Glucose is responsible for supplying energy to the brain, muscles, and other body organs and tissues [

  21

  ]. It’s also the building block for other structural molecules in your body (such as glycoproteins and glycolipids), and is naturally found in fruits, grains, beans, vegetables, nuts, and molasses. However, it can also be found in processed foods and is considered to be an added sugar when used outside of its natural state.

• Fructose: Contrary to glucose, fructose is metabolized in the liver and is used to replenish liver glycogen and synthesize triglycerides [

  10

  ]. As such, studies have found that a diet high in fructose (by way of added sugars) may overload the liver and increase fat deposition, which can contribute to a range of metabolic problems [

  11

  ]. 

When it comes to fructose vs. glucose, it’s best to consume them in their natural forms, as experts agree that all types of added sugar are more damaging than sugar naturally found in foods.

Natural sugar vs. added sugar

Not all sugar is created equal. Here’s what science has to say about natural sugar vs. added sugar. 

Natural sugar

As the name suggests, these sugars occur naturally in fruit (fructose), vegetables, grains, and dairy products (lactose). Thanks to the fiber and protein present in these foods, the natural sugars are digested and absorbed into the bloodstream at a slower rate, thus providing a steady supply of energy to your cells. They also contain other essential nutrients, like vitamins, minerals, and antioxidants, that are needed for energy metabolism, immune function, cell health, and more. Moreover, a diet rich in fruits and vegetables can help reduce the risk of chronic diseases, such as diabetes, heart disease, and some cancers.

Refined sugar

This type of sugar is processed from sugar cane or sugar beets and is typically found as sucrose (a combination of glucose and fructose). Unlike naturally occurring sugars in whole foods that are typically paired with fiber and/or protein, your body rapidly breaks down refined sugars causing insulin and blood sugar levels to spike. Additionally, refined sugars contribute a large number of calories but have little nutritional value otherwise [

1

]. Diets high in refined (or added) sugars can increase your risk of diabetes, obesity, heart disease, cancer, and cognitive decline [

22

].

High fructose corn syrup vs. sugar

High fructose corn syrup is a type of refined sugar that is derived from corn syrup, and is used as a cheap additive by many food manufacturers to sweeten food. Unfortunately, studies have found that the fructose in HFCS is associated with an increased risk of fatty liver disease, obesity, inflammation, heart disease, and type 2 diabetes [

4

,

5

,

6

,

7

].

HCFS appears to come with similar downsides to other forms of added sugar. Studies have found that any added sugar which contains fructose or galactose can’t be used by the body, and will instead be converted to glycogen, uric acid, and lactic acid (all which are harmful in large quantities) [

8

,

9

]. Since sucrose (aka table sugar) is a combination of fructose and glucose, it will most likely have the same negative effect in your body as HFCS.

How many grams of added sugar per day?

Added sugars provide limited nutritional value or health benefits, which is why the American Heart Association recommends limiting added sugars to no more than 6% of calories/day [

2

]. This equates to:

• Men: No more than 150 calories/day (36 g or 9 teaspoons)

• Women and children aged 2+: No more than 100 calories/day (25 g or 6 teaspoons)

• Children under 2: Added sugar is not recommended

Fructose and weight gain

According to the Dietary Guidelines, the average American consumes 270 calories (or 17 teaspoons) of sugar/day, which is significantly higher than the recommended amount [

12

]. This surplus is a risk factor for many chronic diseases, including heart disease, diabetes, cancer, and obesity. 

Here are some ways that excess fructose consumption (by way of added sugars) can negatively impact the number on the scale. 

Insulin resistance.

Excess fructose consumption has been found to have a negative impact on insulin. Studies show that fructose doesn’t stimulate insulin secretion from pancreatic β cells, which can impair insulin signaling and may lead to obesity and type 2 diabetes [

14

,

15

]. 

Might promote overeating.

Research shows that those who consume excess fructose may have a tendency to overeat. When measuring brain activity in people who consumed fructose, researchers discovered that the areas of their brains which regulate appetite (like the hypothalamus, insula, and striatum) and control satiety were not affected, which might trigger overeating [

16

,

17

]. 

Leptin resistance. 

Increased fructose intake has been associated with leptin resistance which may promote obesity [

18

]. Leptin is a negative feedback hormone that signals fullness after consuming food.

Increased caloric intake.

It’s estimated that fructose accounts for 10% of caloric intake in the US thanks to the addition of HFCS found in many soft drinks and processed foods [

13

]. These items contain “empty” calories with very little nutritional value and are easily over-consumed, which can contribute to weight gain.

How to curb fructose intake

Cutting back on refined sugar may be challenging at first, but it gets easier over time. Here are some ways you can reduce your fructose intake, reduce the risk of chronic disease, and help manage your weight.

• Don’t shy away from fruit. Fruit isn’t your enemy! While it’s a natural source of fructose, it also provides a plethora of vitamins and minerals that contribute to overall health. So, instead of adding sugar to your morning oatmeal, reach for some fresh fruit–this will provide added flavor and nutrition while satisfying your sweet tooth.

• Limit sugar-laden drinks. Fructose can be found in many processed drinks–like fruit juices, sodas, cocktail mixes and energy drinks–so it’s best to limit these items and choose non-added sugar beverage alternatives instead. Water is best, but if you want something else to drink, fruit-infused water or seltzer with a squeeze of fresh citrus are other healthful choices.

• Choose more whole foods. Whole foods like fruits, vegetables, whole grains, and legumes are free of additives and other preservatives (such as HFCS). By keeping these items in your kitchen, it may be easier to cut back on high-sugar foods.

• Engage in physical activity. Studies show that physical activity can offset the negative effects of a high-fructose diet and may even decrease

  cardiovascular risk factors

  [

  19

  ]. While any amount of activity is better than none, aim for 30 minutes of exercise/day for optimal benefits.

• Read the label. It’s estimated that 75% of packaged foods contain added sweeteners (such as brown sugar, corn sweetener, HFCS, honey, malt syrup, molasses, and turbinado sugar), so it’s recommended to read food labels before purchasing [

  20

  ].

Summary

Fructose is a monosaccharide that naturally occurs in fruit, but food manufacturers often use it in the form of high fructose corn syrup (HFCS) to sweeten food. Studies have found that HFCS has been associated with a host of health issues (such as fatty liver disease, inflammation, heart disease, and type 2 diabetes), and can even lead to weight gain or obesity. Eating more whole foods, cutting back on sugar-laden beverages, and engaging in physical activity are just some of the ways you can reduce your fructose consumption, manage your weight, and improve overall health.

Disclaimer: The text, images, videos, and other media on this page are provided for informational purposes only and are not intended to treat, diagnose or replace personalized medical care.