Doctors Have Been Saying Sugar Is Bad – But They Missed This

Sugary soda has highest sugar content and zero nutritional value. 

By Brigham Young University

A massive new study reveals that the source of sugar makes all the difference. While sugary drinks like soda and even fruit juice sharply increase the risk of type 2 diabetes, sugars in solid foods—especially nutrient-rich ones—may actually be less harmful or even protective. The findings challenge long-standing dietary assumptions and suggest it’s time to rethink how we talk about sugar and health.

For years, we’ve heard that sugar is one of the main drivers behind the global rise in type 2 diabetes. But new research from Brigham Young University is changing the way we look at sugar. According to the findings, where your sugar comes from matters just as much as how much you consume.

In the most extensive analysis of its kind, researchers from BYU and institutions in Germany examined data from over 500,000 people across multiple continents. Their discovery? Sugars from drinks like soda and even fruit juice were consistently linked to a higher risk of developing type 2 diabetes (T2D). Surprisingly, sugars from other sources did not show this same risk. In fact, some were even linked to a lower risk.

Why Drinking Sugar Is Riskier

“This is the first study to draw clear dose-response relationships between different sugar sources and type 2 diabetes risk,” said Karen Della Corte, lead author and BYU nutritional science professor. “It highlights why drinking your sugar—whether from soda or juice—is more problematic for health than eating it.”

Even after accounting for factors like body mass index, overall calorie intake, and several other lifestyle risk factors, the differences were striking:

• With each additional 12-oz serving of sugar-sweetened beverages (i.e., soft drinks, energy drinks, and sports drinks) per day, the risk for developing T2D increased by 25%. This strong relationship showed that the increased risk began from the very first daily serving with no minimum threshold below which intake appeared to be safe.
• With each additional 8-oz serving of fruit juice per day (i.e., 100% fruit juice, nectars and juice drinks), the risk for developing T2D increased by 5%.
• The above risks are relative not absolute. For example, if the average person’s baseline risk of developing T2D is about 10%, four sodas a day could raise that to roughly 20%, not 100%.
• Comparatively, 20 g/day intakes of total sucrose (table sugar) and total sugar (the sum of all naturally occurring and added sugars in the diet) showed an inverse association with T2D, hinting at a surprising protective association. 

The Metabolic Consequences of Liquid Sugar

Why drinking sugar would be more problematic than eating sugar may come down to the differing metabolic effects. Sugar-sweetened beverages and fruit juice supply isolated sugars, leading to a greater glycemic impact that would overwhelm and disrupt liver metabolism, thereby increasing liver fat and insulin resistance.

On the other hand, dietary sugars consumed in or added to nutrient-dense foods, such as whole fruits, dairy products, or whole grains, do not cause metabolic overload in the liver. These embedded sugars elicit slower blood glucose responses due to accompanying fiber, fats, proteins, and other beneficial nutrients.

Fruit Juice Isn’t a Free Pass

Fruit juice, even with some vitamins and nutrients, is much less beneficial. Because of its high and concentrated sugar content, the researchers conclude that fruit juice is a poor substitute for whole fruits, which provide more fiber to support better blood glucose regulation.

“This study underscores the need for even more stringent recommendations for liquid sugars such as those in sugar-sweetened beverages and fruit juice, as they appear to harmfully associate with metabolic health,” Della Corte said. “Rather than condemning all added sugars, future dietary guidelines might consider the differential effects of sugar based on its source and form.”

Reference: “Dietary Sugar Intake and Incident Type 2 Diabetes Risk: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies” by Karen A Della Corte, Tyler Bosler, Cole McClure, Anette E Buyken, James D LeCheminant, Lukas Schwingshackl and Dennis Della Corte, 21 March 2025, Advances in Nutrition.
DOI: 10.1016/j.advnut.2025.100413 

BYU professors James LeCheminant and Dennis Della Corte, as well as students Tyler Bosler and Cole McClure, were also co-authors on the study, recently published in the journal Advances in Nutrition.