How Many Days It Takes for Junk Food to Spark Food Obsession in Men

Snacking and indulging in moderation is what keeps weight-loss diets sustainable, however a cheat meal here and there isn't a substitute for full-on binging. 

Turns out a week-long gorge can do more than inhibit a lower body fat percentage; it can actually spark a food obsession in your brain, new research shows.

As luck would have it, just five days of consuming junk food can significantly alter your brain activity, according to a recent study published in Nature Metabolism. 

The study followed 29 healthy adult men between the ages of 19 and 27 over five days. During the five-day period, nearly half of the participants maintained their normal diets while the other half consumed an extra 1,500 calories of ultra-processed foods. By using MRI scans, the researchers discovered insulin sensitivity in the participants drastically dropped.

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A decreased insulin sensitivity is commonplace among overweight and obese individuals. Reduced insulin sensitivity generally occurs because excess body fat causes inflammation and releases substances that disrupt how insulin works. 

Why does this matter? In a body that's considered healthy, insulin works to control your appetite by sending signals to the brain to reduce hunger and food intake. When someone is insulin-resistant (common for individuals who are obese or have type-2 diabetes), the brain no longer responds to insulin properly. 

This can lead to problems with metabolism and eating habits as overeating becomes commonplace. As a result, people with poor insulin sensitivity may store excess fat, have a harder time processing energy, and are more likely to regain fat after losing weight.

Other research also shows that individuals with increased insulin resistance have a higher chance of food intake sparking the reward systems in the brain. In this case, food can be viewed by the brain as addictive and lead to higher-than-recommended caloric consumption and food addictions.

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The strange thing is even after the participant's diets returned to normal, their insulin sensitivity levels didn't just return overnight. In fact, it took an entire extra week for those who consumed junk food to get their levels back to their original state. 

Although the study was small and only followed men for a short period of time, this isn't the first time research has shown that junk food is highly addictive. Research shows that highly processed foods (aka foods high in refined carbohydrates and fat) are actually made to trigger the reward systems and addictions in our brains. With hard-to-resist ingredients like dextrose, high levels of salt, and sugar, and more, it's not exactly shocking.