This new study shows obesity involves more than accumulating excess fat and carrying excess weight. During the development of obesity, skeletal muscles fail to adjust their molecular composition appropriately to the increasing body weight. Consequently, the muscles of obese mammals are not properly ‘tuned’ to the higher body weight they carry. This may explain why muscle strength and locomotion are impaired in obese humans and why it is difficult to lose excess weight.

Journal of Experimental Biology, May 2011