The calf muscles are what are called slow twitch muscles which means that the calf muscles are, for the most part, made up of slow-twitch muscle fibers, fibers that are best at endurance feats. The gastrocnemius and the soleus run between the knee and the ankle.
Therefore the most common causes of obesity are overeating and physical inactivity. Ultimately, body weight is the result of genetics, metabolism, environment, behavior, and culture. 1  Genetics. 2  A person is more likely to develop obesity if one or both parents are obese. 3  Genetics also affect hormones involved in fat regulation. 4  For example, one genetic cause of obesity is leptin deficiency.
The proportion of adults who are obese increases with age; obesity can be caused by the cumulative effect of years of eating just a little more than we should. While less than 33 percent of us are obese between the ages of 20 and 39, nearly 40 percent of Americans older than 60 are obese.