Can sugar in fruits trigger weight gain? A new study uncovers how fruit sugar spurs calories & fat storage

Unlike glucose, which is metabolised throughout the body, fructose is primarily metabolised in the liver. Excessive fructose intake can overwhelm the liver’s capacity to process it, leading to the conversion of fructose into fat molecules, which are then stored in the liver as well as in the adipose tissue, says Dr Subhash Kumar Wangnoo, Senior Consultant Endocrinologist and Diabetologist, Apollo Hospitals, New Delhi

Fructose, when consumed in moderation through whole fruits, can be part of a healthy diet due to its fibre content (Source: Unsplash)

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Next time you want to dribble maple syrup over your millet pancakes, pour out a packaged fruit juice, toss a pre-mixed bowl of oats into the microwave, load your salad with dressings and relish or reach out for a fancy-sounding bread, know that you have turned your supposedly healthy meal unhealthy. That’s because all of these contain fructose, a naturally occurring sugar found in fruits, which when added to processed foods, can lead to fat build-up and obesity.

A new multi-centre review, published in the Philosophical Transactions of the Royal Society B, suggests that fructose may drive obesity due to an evolutionary “survival switch” that causes people to store energy from fructose rather than using it. This would suggest that while glucose is used as an immediate fuel, fructose triggers the body to store it as calories and fat. While this crisis response works when the person is in a food-deprived scenario, it can harm the body when the person has continuous access to high-sugar foods. Unless calorie intake is reduced, this lower energy usage results in weight gain.

Fructose metabolism differs from glucose metabolism (Designed by Abhishek Mitra)

Fructose, when consumed in moderation through whole fruits, can be part of a healthy diet due to its fibre content and slow absorption. Besides, we do not exactly gorge on fruits but have them in small amounts. However, excessive consumption of fructose, especially when it is concentrated in the form of added sugars like high-fructose corn syrup (HFCS), has been associated with several mechanisms that promote weight gain and obesity. HFCS is often added to foods that are already high in fat or sugar, pushing up the risk of obesity.

First, fructose metabolism differs from glucose metabolism. Unlike glucose, which is metabolised throughout the body, fructose is primarily metabolised in the liver. Excessive fructose intake can overwhelm the liver’s capacity to process it, leading to the conversion of fructose into fat molecules, which are then stored in the liver as well as in the adipose tissue.

Second, fructose consumption does not stimulate insulin secretion to the same extent as glucose. This can result in decreased leptin production, a hormone responsible for signalling satiety to the brain. Consequently, individuals who consume high amounts of fructose may not feel as satisfied after meals, leading to overeating and excess calorie intake.

When managing fructose intake, opt for fruits with lower fructose content like berries, citrus fruits, and melons. Vegetables like leafy greens, cucumbers, and bell peppers are good choices. Incorporate whole grains, lean proteins and healthy fats. Avoid high-fructose corn syrup and limit consumption of sugary beverages, desserts and processed foods.

Moderation is the key. Monitor portion sizes and read labels. Consulting a registered dietitian can provide personalised guidance. Remember, balanced eating with a focus on whole, fibre-rich and unprocessed foods is essential for overall health when dealing with fructose sensitivity.

Furthermore, fructose intake may disrupt hormonal regulation related to appetite control. It can increase levels of ghrelin, a hormone that stimulates hunger, while reducing levels of peptide YY, a hormone that signals fullness. This hormonal imbalance can contribute to increased food consumption, especially energy-dense, nutrient-poor foods.

The modern Western diet, rich in sugary beverages, processed foods, and sweets, often leads to excessive fructose consumption. The high availability and low cost of HFCS-containing products exacerbate this issue. Almost all processed foods contain HFCS. These include sodas, sweetened fruit juices, crackers, pre-prepared meals, condiments, salad dressings, some breads and pastries, honey, agave syrup, maple-flavoured syrup, molasses, palm or coconut sugar.

It’s essential to recognize that while fructose is not solely responsible for obesity, its excessive intake can be a significant contributor when combined with other dietary and lifestyle factors.