After a week or two of vacation, when regular diets and exercise routines are put on hold, weight gain is often an expected side effect. But the real challenge comes when you find it hard to cut back on eating even after returning to normal. Researchers now have an explanation: short-term, high-calorie diets do not just show up on the scale; they affect the brain.
A recent study published in the journal Nature revealed that even short-term overeating of high-sugar and high-fat foods can affect the brain of a healthy person, causing it to function similarly to that of an obese individual. A more alarming finding was that brain changes occur even before a person starts noticing weight gain.
"Our data indicate that the brain and behavior response resemble that of a person with obesity and changes in the brain seem to occur prior to weight gain," Prof Stephanie Kullmann, lead researcher of the study told the Telegraph.
The researchers noted that the brain's return to normal took longer than expected, explaining why cravings for such foods last for a longer period.
"The changes in the brain outlasted the timeframe of the consumption. Behaviorally, we see that participants show changes in reward behavior: Reduced reward sensitivity, this could lead to greater food intake," Prof Kullmann added.
The study evaluated 18 young and healthy men who were put on a high-calorie diet rich in sugary and fatty foods, comparing the changes in their brains with those of 11 men who maintained a normal diet. Over the course of five days, the participants on the high-calorie diet consumed about 1,200 extra calories per day compared to their usual intake.
After the five-day high-calorie diet, although there was no significant weight gain, the researchers noted substantial changes in the participants' brains as revealed by tests conducted one week later. The brains of the participants had higher levels of insulin resistance compared to the participants in the control group.
"In conclusion, we show that short-term overeating with commonly used ultra-processed high-caloric snacks can trigger liver fat accumulation and short-term disrupted brain insulin action that outlast the time-frame of the HCD (high-calorie diet) in men," the researchers wrote.
