BRAIN HARDWIRING APPEARS TO INFLUENCE WEIGHT GAIN
In a fascinating study published in the Proceedings of the National Academy of Sciences, a research team led by Tamas Horvath at the Yale School of Medicine has published findings that indicate our brains are hardwired in different ways. Some of us are born with and continue to develop brains that do a better job at signaling satiety or fullness after taking in an adequate number of calories. In other brains, the hardwired neurons do not. In addition, the hardwiring of brains associated with obesity may be less effective sending signals to the body to burn excess calories instead of storing them.
The Yale School of Medicine study examined rats and assessed particular brain mechanisms associated with eventually becoming obese. Some of the rats were likely to become obese with a high calorie obese while other rats were not likely to become obese. There appears to be both some hardwiring that occurs at birth as well as some changes over time in the brain cells, or neurons, that affect whether an individual gains weight and becomes obese, or simply maintains a healthy weight, even on a high calorie diet.
One of the most interesting, but troubling findings of the study is that the brains of some individuals who are more susceptible to diet induced obesity exhibit a type of brain inflammation, whereas those individuals who are resistant to diet induced obesity do not. The concern is that this type of change in the brain or inflammatory response of the brain with weight gain, may explain why it is so hard for obese individuals to lose weight and keep it off once changes in the brain have already occurred.
More studies will lead to a better elucidation of the exact mechanisms by which certain neurons signal for the sensation of satiety or fullness and the decisions to stop eating or drinking further calories. Additionally, we hope to learn more about how the brain signals whether calories are stored as more fat or whether they are burned. What is clear is that some individuals are more prone to obesity than other individuals. Yet, the primary change that has taken place in the last forty years is not one of the genetics of our brain cells, but is one of the changing environment around us and the dramatic increase in the calorie content of foods, drinks and meals, such that most of us are consuming 30-40% more calories than our predecessors were forty years ago.
So while the rat studies indicate that some of us are likely to be more protected or resistant to obesity with this new high calorie diet, most of us are not. If public health predictions hold true, very soon the percentage of all Americans who are overweight or obese will approach 100%.