There’s new evidence that consuming fructose worsens the effects of high-fat diets like keto by hurting the liver’s ability to burn fat.
Studying fructose
For a new study on the effects of fructose, researchers from Harvard Medical School separated mice into six groups, including:
- Group 1: Mice who ate a regular diet
- Group 2: Mice who ate a regular diet with high glucose
- Group 3: Mice who ate a regular diet with high fructose
- Group 4: Mice who ate a fat diet only
- Group 5: Mice who ate a high fat diet with high glucose
- Group 6: Mice who ate a high fat diet with high fructose
As was expected based on previous studies, all the mice in Groups 2 and 3 gained approximately 30% more weight than Group 1. In addition, the mice in Group 1 didn’t develop high blood glucose, a symptom of diabetes.
All three of the latter groups (4-6) developed obesity and increased their body weight by an average of 40 to 60%. They also all showed signs of fat build-up in and enlargement of the liver.
What the researchers discovered was that while the mice in Groups 4 and 6 developed insulin resistance and high blood sugar and their insulin doubled, the mice in Group 5 didn’t develop these symptoms. (They did gain a similar amount of weight as the mice in Groups 4 and 6 though.)
The findings
The researchers found that the mice on the high-fat diets with high glucose had lower levels of high liver fat markers, suggesting that glucose aids the liver in burning fat.
The team also noticed that the mitochondria of the mice in Group 5 seemed to be healthy, while the mitochondria in Group 6 were not. This suggests that fructose affected the mice’s ability to burn fat.
