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.
Medical Causes of Obesity Obesity is usually the result of overeating, but in a small percentage of people excess weight gain is a symptom of another disease. Medical causes of obesity can include: Hypothyroidism. This is a condition where the thyroid gland, located in the neck, produces too little thyroid hormone. Thyroid hormone regulates our metabolism. So too little hormone slows the metabolism and often causes weight gain.