It’s difficult to lose weight, but it can be even harder to maintain a healthy weight weight once you’ve achieved it. Often, when we regain weight, we blame ourselves of a lack of will power, but more and more research confirms that there are strong physiological reasons why weight loss can be so challenging and why diets can be a recipe for ‘failure’.
A symposium held recently in Washington, DC, organized by The Journal of Physiology, focused on recent work in talks by leaders in the field. The speakers discussed state-of-the-art data and models regarding the brain as an initiator of obesity and as a target organ of peripheral feedback signals that regulate feeding behaviour. Reports of the talks by Barry Levin, Mary Dallman, and Gregory Morton are published in the September 1 issue of The Journal of Physiology, and they provide intriguing insights into the physiological basis of obesity.
Current statitics show that, once obesity occurs, fewer than 10% of affected individuals can sustain permanent weight loss success. In some individuals, there may be a decreased ability to sense and respond to fullness, satiety and other signals from the body which should limit their food intake when it exceeds their metabolic needs.
In times of nutrient abundance and excess energy storage, the brain promotes reduced food intake and increased energy expenditure. People with an impaired ability of the brain to respond to hormonal or nutrient-related signals may be more likely to gain weight, develop insulin resistance and type 2 diabetes.
Why Diets Don’t Work
The physiological drive to seek and ingest food and limit energy expenditure during periods of weight loss provide an irresistible urge to regain lost adipose stores in weight-reduced obese individuals. Dr. Morton discussed that during a reduction in calories and circulating nutrients, the brain initiates responses to restore and maintain energy and glucose homeostasis. This provides a potential basis for the well-recognized difficulty of maintaining weight loss.
In addition, Dr. Dallman reported that conditions of reduced food allowance and chronic stress excite central neural networks that may lead toward abdominal obesity. This provides a potential link between stress and obesity.
Researchers are hopeful that future studies will provide improved preventive and therapeutic insights.
Note: This story has been adapted from a news release issued by Blackwell Publishing Ltd..
For full abstract and study:
Barry E. Levin (2007)
Why some of us get fat and what we can do about it
The Journal of Physiology 583 (2), 425–430.
By Laura Brooks