Dr. Leah Whigham of the Dept of Nutritional Sciences, Wisconsin University agrees that the obesity phenomenon could, in part, be due to an infectious virus that can be passed from person to person. Whigham says people are a lot more comfortable believing that lack of control is the only explanation for being fat. However, she points out, ulcers used to be attributed to stress, but scientists now know that the virus H. pylori is a factor. In total, Whigham says there are three viruses that have been identified as causing chickens—and most likely humans—to be fatter. In some studies, humans with a high Body Mass Index were found to be five times more likely to have antibodies to Ad-36, than those who were not obese. Whigham, Dhurandhar and others are interested in finding out how many of the other roughly 50 adenoviruses common to humans could possibly pose this threat, as well.http://www.dailygalaxy.com/my_weblog/2007/11/the-obesity-phe.html

I like the viewpoint by Field, A. E., Camargo, C. A., & Ogino, S. (2013). The Merits of Subtyping Obesity: One Size Does Not Fit All. JAMA, 310(20), 2147-2148. In this viewpoint, the authors argue that "One reason for the lack of stronger associations with risk factors or more consistently successful treatment is that all types of overweight and obesity are often grouped together. This approach potentially obscures strong associations between risk factors and specific subtypes of obesity."

Experts say lack of exercise, heavy intake of junk food and decreased mobility such as using cars and bikes for travelling short distances are all to blame. Today, everything is available at the click of the finger, or a tap on the smartphone. At a time when people struggle to find time to exercise, smartphone apps and internet shopping have made life even more convenient, though at the expense of any physical activity whatsoever.

http://www.newindianexpress.com/lifestyle/health/Fat-is-Not-For-the-Fit/2014/11/01/article2501894.ece

Obese people are better at detecting the scent of chocolate and find it more pleasant than non-obese people, according to a small UK study.

Recent research suggests that smell plays a large role in people’s food intake, as the sense of smell is linked to the hunger center in the brain, the researchers write in Chemical Senses.

http://in.reuters.com/article/2015/04/03/us-health-obesity-olfaction-idINKBN0MU18V20150403

Multiple causes, and heterogeneous individuals, make it difficult to disentangle the primary causes of obesity and therefore difficult to translate what we know to a one size fits all practice.  We do know that there are genetic, psychological, social, and individual preference factors that drive choices and subsequently outcomes.  So where do we begin?  Regardless of these factors, excessive food intake (lifestyle) is a consequence and thus responsible for much of the epidemic.  Which suggests some addictive habits and tendencies.  As with any addictive tendency - the individual has to want to change.  And that is why psychosocial well-being is likely the root of the problem.  Their choices may suggest revealed preferences for lower life expectancy to enjoy and live for today.  But what is not revealed is the underlying psychological factors that drive those apparent "preferences".  A doctor saying "you are going to die" is not enough.  A surgical procedure to physically force behaviors is not sustainable.  It's the mind.