Identification

• Barring significant lifestyle changes, weight and body type of adult to middle-aged men remain stable from year to year. Conversely, the Mayo Clinic identifies unexplained weight loss as notable decreases in weight during times when the patient has no intent of slimming down. Unexplained drops in weight of more than five percent of total body weight may require medical attention.
  
  

Diet and Exercise

• Men lose weight by using more calories (energy) than they consume (food). Men that make healthy eating choices, along with maintaining a consistent workout regimen, will increase their metabolism and testosterone levels, burning fat and building lean muscle.
  
  

Aging

• Testosterone levels decrease with age, in what is referred to as andropause. Men tend to lose muscle mass after age 35. Food consumption and skeletal muscle patterns natural regress in elderly men.
  
  

Malnutrition

• Excessive weight loss may be attributed to malnutrition. Malnourished bodies cannibalize themselves by consuming fat and muscle tissue for energy.
  
  

Disease

• Poor mental and physical health causes excessive weight loss. Depression, cancer, diabetes and various gastrointestinal ailments adversely affect appetite and the digestive system. Additionally, medication and surgery prescribed to treat ailments may cause men to drop weight.