These Foods Have Been Linked To Brain Changes That Can Trigger Obesity
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There are certain lifestyle habits that are clearly linked to weight gain, like not being active in your daily life and eating a diet filled with ultra-processed foods. But new research suggests that certain foods may actually trigger changes in your brain that could raise your risk of developing obesity.
Of course, obesity is a complex chronic disease, and eating certain foods once in a while won't automatically cause you to develop the condition. But this new study has raised a lot of questions about how your diet and brain health can have total-body impacts. So, to help parse the science, Women's Health asked some experts to break down these findings and explain what they mean for you (and your kitchen cupboard!).
Meet the experts: Mir Ali, MD, medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA; Jessica Cording, RD, CDN, author of The Little Book of Game-Changers; Scott Keatley, RD, co-owner of Keatley Medical Nutrition Therapy
What did the study find?
The study, which was published in Nature Metabolism, recruited 29 average-weight men and split them into two groups. One group was asked to supplement their regular diet for five days with an additional 1,500 calories from highly-processed, high-calorie snacks, while the other group didn’t consume those extra calories.
The researchers had the participants undergo a series of tests (including magnetic resonance imaging, or MRI, imaging) at the start of the study, five days after starting the study, and seven days after going back to their usual diet.
After five days, the researchers discovered that people in the extra calorie group experienced a significant jump in the amount of fat in their livers. But the researchers also discovered that the participants in this group had significantly lower insulin sensitivity a week after going back to their regular diet compared to the control group, suggesting that their bodies weren't processing foods in as healthily or efficiently as before.
In case you’re not familiar with it, insulin sensitivity is a measure of how effectively the body’s cells respond to the hormone insulin, which allows glucose to be converted into energy in the body. Low insulin sensitivity, or insulin resistance, is linked to a higher risk of developing diabetes and obesity.
As a result, the researchers concluded that the “brain response to insulin can adapt to short-term changes in diet before weight gain and may facilitate the development of obesity and associated diseases."
How does insulin impact the brain?
Insulin actually plays a big role in the brain, including influencing the hippocampus, an area linked to reward recognition. It also influences your food intake, says Mir Ali, MD, medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA.
"Insulin isn’t just about blood sugar—it plays a crucial role in the brain by regulating appetite, metabolism, and even cognitive functions like memory and learning," explains Scott Keatley, RD, co-owner of Keatley Medical Nutrition Therapy. "When insulin is working properly, it signals the brain to reduce hunger and helps neurons use glucose efficiently for energy."
But insulin's impact on the brain can be influenced by other factors, including what you eat, as the study results showed. “Having large amounts of high carbohydrate, high fat foods can cause insulin secretion to be altered in all organs, including the brain,” Dr. Ali says. Those foods can increase cravings, and lead to poor appetite control and a greater risk of developing obesity and metabolic disorders, according to Dr. Keatley.
In this case, eating high-carb, high-calorie foods may make it harder for your body to process the fuel you eat and may also work against your efforts to eat healthy—even days after you had a lot of junk food.
What kinds of foods are responsible for changes in the brain?
This study specifically looked at foods that were considered "highly processed" and high in calories, with a nutritional breakdown of 47 to 50 percent fat and 40 to 45 percent carbohydrates.
The researchers called these specific foods out in the study, mentioning they were some of the snacks that were eaten by participants:
Snickers
Brownies
Chips
Kit Kats
M&Ms
Can you reverse this brain change?
This particular study didn’t look into whether you can reverse the brain changes that result from eating highly processed, calorie-dense foods, but Dr. Ali says it’s possible. If you feel like your dietary habits have taken a nosedive lately, he recommends doing your best to get back on track by focusing on lean proteins and vegetables. Focus on eating a mix of protein, fat, and fiber at every meal to help you get in plenty of nutrients while still feeling satisfied, says Jessica Cording, RD, CDN, author of The Little Book of Game-Changers.
Regular exercise and good sleep can help manage insulin levels too. "Both cardio and strength training boost insulin sensitivity in the brain," Dr. Keatley says. "Poor sleep disrupts insulin signaling, while good sleep helps reset brain metabolism."
Don’t count yourself out if you've just dug into a bag of chips or candy. “Just like unhealthy eating only took a short time to cause some abnormality, healthy eating can help reverse the effects,” Dr. Ali says.
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