Weight loss may be impacting more than your waistline. A new study is showing how weight loss can also change your brain.

For some individuals, bariatric surgery is needed to improve obesity and give people a chance to live a healthy life. With bariatric surgery comes weight loss and that may have some surprising effects on the brain. For those who lost weight after bariatric surgery, the brain responded differently to food cues.

The study was led by Rachel Goldman, PhD, from the New York University Langone Medical Center. The researchers collected MRI scans from 40 patients after bariatric surgery. For the 27 patients who successfully lost weight after surgery, different parts of the brain were activated when compared to the 13 patients who were not successful in losing weight after surgery.

Researchers did not allow any foods four hours prior to getting two MRI scans. Each of the patients looked at 24 photos, 12 of food and 12 of neutral objects. For the first scan, patients were asked to indulge in their cravings from the food images while the second scan required the patients to resist any food cravings caused by the food-related images.

There was increased level of activity in the prefrontal cortex, insular cortex and posterior cingulate in response to food craving for patients who successfully lost weight. These areas of the brain seem related to resistance of the cravings. Compared to patients who did not lose weight, there was no identifiable pattern of brain activity.

The different brain activity in bariatric surgery patients can have some promising effects on how successful the treatment may be. The major limitation of the study was that the researchers did not measure brain activity before the surgery.

Future research can include four sets of MRI featuring before and after brain activity for patients who did and did not lose weight. By having this data, researchers could determine if brain activity changed or remained the same. For example, if the brain activity in response to food craving for patients who lost weight was the same before and after surgery, it may help better predict which patients may be more successful after treatment, note researchers.

The reasons for weight loss or gain after surgery could be due to a number of factors and understanding brain activity may help doctors provided better post-operative care. When talking to Dr. John Morton, director of bariatric surgery at Stanford Hospital and Clinics, weight gain could be due to a lot of factors including "they forget to keep their portion sizes small, or they snack too frequently, or they consume high calorie liquid foods. Stress, people will go back to bad habits when they get stressed."

Another factor, according to researchers, could be due to how the brain responds to food cues. The brains of obese individuals may be more sensitive to food cues, thus increasing the risk to overeat. Future research can help determine just how important the brain is in regards to weight loss.

The study was presented at the 2012 American Society for Metabolic and Bariatric Surgery meeting and should be considered preliminary until published in a peer-reviewed journal.