Commentary: While nothing in this article is shockingly new - we have discussed ad infinitum the changes in the brain and leptin sensitivity in the chronically obese - this article is shocking because in true medical orthodoxy fashion it suggest the answer is pharmaceutical intervention for the "weak will" of the obese. I was obese for close to a decade. My brain and leptin sensitivity was altered. And then after a decade of proper nutrition and "activity", it has been successfully altered BACK. This research just gives the obese person another excuse as to why its not their fault they are obese or are unsuccessful at their attempts at staying leaner and healthier. This is a shame. We know that hormones may play a role in stimulating hunger. But giving in to hunger is optional. And WHICH foods you eat make an even bigger impact on whether or not you will regain your weight. Don't be fooled by this research. I was fat and it was my fault. I am lean and healthy now.. and that's my fault too. - Carl

Worldwide, there are more than 1.5 billion overweight adults, including 400 million who are obese. In Australia, it is estimated more than 50 per cent of women and 60 per cent of men are either overweight or obese.

Although restriction of diet often results in initial weight loss, more than 80 per cent of obese dieters fail to maintain their reduced weight.

The study involved 50 overweight or obese adults, with a BMI of between 27 and 40, and an average weight of 95kg, who enrolled in a 10-week weight loss program using a very low energy diet. Levels of appetite-regulating hormones were measured at baseline, at the end of the program and one year after initial weight loss.

Results showed that following initial weight loss of about 13 kgs, the levels of hormones that influence hunger changed in a way which would be expected to increase appetite. These changes were sustained for at least one year. Participants regained around 5kgs during the one-year period of study.

Professor Joseph Proietto from the University of Melbourne and Austin Health said the study revealed the important roles that hormones play in regulating body weight, making dietary and behavioral change less likely to work in the long-term.

"Our study has provided clues as to why obese people who have lost weight often relapse. The relapse has a strong physiological basis and is not simply the result of the voluntary resumption of old habits," he said.

Dr Proietto said although health promotion campaigns recommended obese people adopt lifestyle changes such as to be more active, they were unlikely to lead to reversal of the obesity epidemic.

"Ultimately it would be more effective to focus public health efforts in preventing children from becoming obese."

"The study also suggests that hunger following weight loss needs to be addressed. This may be possible with long-term pharmacotherapy or hormone manipulation but these options need to be investigated," he said.

The study was done in collaboration with La Trobe University.

The "switching on" or expression of specific genes in the human genome is what makes each human tissue and each human being unique. A new study by researchers at the Johns Hopkins Bloomberg School of Public Health, the Lieber Institute for Brain Development, and the National Institute of Mental Health found that many gene expression changes that occur during fetal development are reversed immediately after birth. Reversals of fetal expression changes are also seen again much later in life during normal aging of the brain. Additionally, the team observed the reversal of fetal expression changes in Alzheimer's disease findings reported in other studies. The research team also found that gene expression change is fastest in human brain tissue during fetal development, slows down through childhood and adolescence, stabilizes in adulthood, and then speeds up again after age 50, with distinct redirection of expression changes prior to birth and in early adulthood. Their findings are published in the Oct. 27, 2011, edition of Nature. All of the data are available to the public as a web-based resource at: http://www.libd.org/braincloud.

Using a number of genomic analysis technologies, the research team conducted genome-wide genetic (DNA) and gene expression (RNA) analyses of brain tissue samples from the prefrontal cortex. Tissue represented the various stages of the human lifespan.

"We think that these coordinated changes in gene expression connecting fetal development with aging and neurodegeneration are central to how the genome constructs the human brain and how the brain ages," said Carlo Colantuoni, PhD, one of the lead authors of the study and a former research associate with the Department of Biostatistics at the Johns Hopkins Bloomberg School of Public Health. Colantuoni recently joined the Lieber Institute for Brain Development on the Johns Hopkins Medical Campus.

The research also showed that brain gene expression differences between genetically diverse individuals (of different races, for example) are no greater than the differences between individuals sharing many more genetic traits.

"Our findings highlight the fact that current technologies and analysis methods can address the effects of individual genetic traits in isolation, but we have virtually no understanding of how our many millions of genetic traits work in concert with one another," added Colantuoni.