A fairly large percentage of individuals, at some point throughout their life, have gained excess body weight. This being true for so many individuals, why are some more likely to lose the excess weight while others aren’t?

For individuals where the weight gain is not related to a physical medical condition, it’s well known that effectively losing weight and thereafter, maintaining a healthier weight level is just as much a mental challenge as it is a physical one.

Without proper motivation, focus, and the implementation of a sound mental strategy, it can be all too easy to succumb to the temptation of returning to your old eating habits. Now, a clinical study on high fat diets is pointing to a very concrete reason as to why that may be.

High Fat Diets Cause Brain Damage Within 24 Hours, Study Says

According to researchers from the University of Washington School of Medicine, consuming high fat diets even briefly can result in a brain injury. During the study, a team of researchers led by Dr. Michael Schwartz placed obese rodents on a high-fat diet. The rodents were purposely made obese through breeding techniques.

According to Schwartz, damage in the hypothalamus region of the brain was observed in the rodents within 24 hours of placing them on high-fat diets. The hypothalamus is responsible for controlling eating urges and sending satiation signals, allowing you to feel full after consuming a meal. Ultimately, the hypothalamus is intended to regulate body weight.

Schwartz said that similar damage can be observed in the hypothalamus areas of obese peoples’ brains. However, the researchers can’t say for sure whether hypothalamus damage leads directly to obesity.

Hypothalamus Damage Causes Obesity, or Vice Versa?

Obesity has a wide range of physical symptoms beyond excess body weight, ranging from increased risk for a number of serious diseases to constant, low-level inflammation that pervades the entire body. According to Schwartz, this inflammation may be responsible for the observed damage to the hypothalamus.

Dr. Joshua Thaler, a University of Washington endocrinologist, said that when the hypothalamus becomes damaged or inflamed, it stops responding to insulin and other hormones intended to regulate body weight.

During the study, mice and rats were given either a normal diet or a high-fat diet over the course of four weeks. After just one week, gliosis was detected in the rodents given a high-fat diet. Gliosis is defined as cell overgrowth indicating that the brain is attempting to recover from an injury.

Gliosis and inflammation were detected for the duration of the high-fat diets, despite the fact that the rodents’ brains were able to self-heal to at least some degree.

Thaler and his colleagues then examined brain imaging scans of 34 individuals, all of whom were healthy despite ranging in body weight from thin to obese. Higher levels of gliosis were detected in the obese individuals than those of a normal body weight.

Because of this, Schwartz and Thaler concluded that the eating habits that produce obesity, or obesity itself, could damage the areas of the brain that regulate body weight. The researchers said that it’s “still unclear” as to whether hypothalamus damage stemming from a high-fat diet is permanent or reversible.

A Few Caveats

Dr. Stephen Hammes, a University of Rochester Medical Center endocrinologist who did not play a role in the aforementioned study, pointed out a few caveats inherent to the work.

First, Hammes noted that the study focused mostly on rodents, and that human brains may respond differently to high-fat diets despite the evidence found in the brain scans. Second, he said that the study doesn’t prove whether obesity changes the hypothalamus or changes to the hypothalamus cause obesity.

Regardless, Hammes said that the study definitely proves a correlation between the condition of the hypothalamus and body weight, if not direct causality, and called the findings “intriguing.”

High Fat Diets: The Bottom Line

According to Hammes, obesity can stem from a number of things, including lifestyle choices such as overeating and a lack of physical exercise, as well as genetic predisposition. However, he said that even those who are genetically predisposed to obesity can avoid the condition by eating a balanced, calorie-conscious diet and engaging in regular physical activity.

A recent study strongly indicates that consuming a diet with excessive amounts of fat, even for a short period of time, could damage the area of the brain responsible for controlling hunger, satiation and, ultimately, body weight. The full text of the study can be found in the December 27, 2011 issue of the Journal of Clinical Investigation.