The ancient Greeks first Active Lean Review Active Lean Review recognized the dangers of obesity. Hippocrates, considered the Father of Medicine,believed that obesity led to infertility and even death. Hippocrates was aware of sudden deaths being more common among obese men than lean ones. He correctly identified the energy balance equation.

Energy cannot be created or destroyed. Energy is either used or stored. When -calories in- are greater than -calories out- then body weight increases.
When -calories in- are less than -calories out-then body weight decreases. After Hippocrates laid the foundation for understanding energy and weight management within the human body, another two thousand years went by before the general public in Europe, in the early 1600s, began to recognize diet and exercise as means to preserving one's health.

Around the 17th century, links between diet, disease, and health were clearly acknowledged. Study after study emphasized the benefits of leanness and the dangers of corpulence. beginning in the 17 the century. The term obesity was first used in 1650 by the English physician and medical writer, Dr. Tobias Venner. With the industrial revolution of the 19th century, England saw a growing abundance of food coupled with an increasingly sedentary lifestyle. The result was a vast increase in obesity among the middle and upper classes.

Unfortunately, as the medical society and the public in general began to look at obesity and its complications as serious health problems, knowledge on how to reverse it, especially permanently, remained unclear. Surprisingly, most 19th century doctors had no idea about its cause. Many thought obesity was due to sin or diseases.