Key Finding:
Just 5 days of eating high-calorie, ultra-processed snacks led to increased liver fat and altered brain insulin activityin healthy young men, with some effects persisting even after returning to a normal diet.
Study Details:
- Participants: 29 healthy men (ages 19–27, normal BMI); 18 had a high-calorie diet (+1500 kcal/day), 11 stayed on a regular diet.
- Duration: 5-day intervention followed by 7 days of normal eating.
- Measurements: Brain insulin response (via MRI), liver fat, insulin sensitivity, and emotional responses to food.
Main Results:
- Liver fat increased significantly after 5 days of high-calorie eating.
- Brain insulin activity increased in certain regions initially, but dropped below normal levels after resuming a regular diet.
- Changes in brain insulin response were linked to fat and carb intake.
- Participants also showed reduced reward sensitivity and increased punishment sensitivity, indicating shifts in food-related brain behavior.
Clinical Implication:
Short-term overeating—even just for 5 days—can lead to measurable changes in the brain and liver, potentially setting the stage for obesity before any weight gain occurs.
Limitations:
- Small sample size.
- Only men were studied.
- Some gold-standard methods for measuring insulin sensitivity weren’t used.
