A new simulation model predicts weight changes with varying diets and exercise plans.  Researchers at the National Institutes of Health (NIH) have created a mathematical model — and an accompanying online weight simulation tool — of what happens when people of varying weights, diets and exercise habits try to change their weight. The findings challenge the commonly held belief that eating 3,500 fewer calories — or burning them off exercising — will always result in a pound of weight loss.

Over the years, we hear about “cancer clusters” or a growing rise in behavioral conditions like autism and advocates and families want answers.  Is it our genes or something in the environment?   This concern often leads to an epidemiological study that tracks these diseases over time.   But sometimes, despite the time, effort and expense, no definitive causation is established.  This  can be frustrating to families facing these conditions and the scientists who are looking for answers.  This is the conundrum of  nature vs. nurture.