Fructose, sucrose and liver fat production in 94 healthy men
What it found
Drinks sweetened with fructose or sucrose doubled the rate at which the liver made new fats in healthy men over 7 weeks.
Glucose drinks did not cause this change.
What they found
Studies in people
Liver fat production
Men who drank fructose or sucrose beverages had twice the rate of new fat production in the liver compared to those who drank nothing sweet. Men who drank glucose beverages showed no such increase.
Fat burning and breakdown
The drinks did not change how fast the body broke down stored fat or burned fat for energy. Total calorie intake stayed about the same across all groups.
Blood fats and sugar
Fasting blood fats, blood sugar and insulin levels did not change after 7 weeks of drinking any of the sweetened beverages.
Cholesterol particle size
In the sucrose group, large cholesterol particles dropped by more than 13% while small, dense particles rose. These smaller particles are linked to heart disease.
What the authors conclude
- They conclude that regular consumption of fructose or sucrose drinks increases the liver's ability to make fats, even when total calorie intake stays the same.
- They note that pure fructose and sucrose caused similar increases, despite sucrose providing only half as much fructose.
- They suggest this shift in liver activity may be the first step toward further changes that affect metabolic health.
How it was done
Scientists debate whether fructose drives fatty liver disease and metabolic problems. The authors wanted to see if moderate amounts of fructose change how the liver handles fats, without people simply eating more calories overall.
Ninety-four healthy lean men drank sweetened beverages every day for 7 weeks alongside their normal meals. They were randomly assigned to drinks containing 80 g per day of fructose, sucrose, glucose, or no sweet drinks at all. Researchers then measured how fast the liver produced new fats and how the body burned them.
What it can’t tell you
- This trial only included healthy lean young men, so it cannot show what happens in women, older adults or people who already carry extra weight.
- The study lasted 7 weeks, so it cannot reveal whether these liver changes lead to long-term diseases like fatty liver or diabetes.
Who paid
- Conflicts
- Conflict of interest The authors have declared that no conflicts of interest exist with regard to this study. Please refer to the accompanying ICMJE disclosure forms for further details.
- Authors work at
- University Hospital Zurich (USZ) and University of Zurich (UZH), Switzerland; Bern University Hospital and University of Bern, Switzerland; Institute for Biomedicine and Health Sciences, Austria
The paper
- Title
- Fructose- and sucrose- but not glucose-sweetened beverages promote hepatic de novo lipogenesis: A randomized controlled trial
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Geidl-Flueck B, Hochuli M, Németh Á, et al (2021). Fructose- and sucrose- but not glucose-sweetened beverages promote hepatic de novo lipogenesis: A randomized controlled trial. Journal of hepatology. doi:10.1016/j.jhep.2021.02.027Free full textPubMed 33684506DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error