Smoking

• Smoking can cause low levels of HDL cholesterol. HDL stands for "high-density lipoprotein" and is also known as the "good" cholesterol. Low levels are considered 40 mg/dL or below for men and 50 mg/dL or below for women. Mg/dL means milligrams of cholesterol per deciliter of blood. Higher levels of HDL can decrease your risk of cardiovascular disease. A study of 4107 individuals found that smoking cigarettes led to an average of 4 mg/dL lower HDL in men and 6 mg/dL in women.
  
  

Obesity and Inactivity

• Being obese can cause your HDL levels to be low. Body Mass Index (BMI) is a measurement of body fat; lowering your BMI through exercise and healthy diet can raise your HDL cholesterol. Exercise itself can also help raise your HDL levels, as inactivity has been linked to lower levels. Moderate to high levels of regular aerobic activity can raise your HDL cholesterol as much as 25 percent.
  
  

Hormones and Steriods

• Testosterone has been associated with lowered levels of HDL. Some men receive testosterone replacement therapy when their testosterone levels are low due to genetic abnormalities or the natural aging process. Lowered testosterone can reduce sex drive, inhibit sexual functioning, and cause fatigue and depression. Men who receive testosterone supplements often have to have their cholesterol monitored as well since the supplements can cause HDL to fall. Anabolic steroids are illegal substances that are used by some athletes to improve athletic performance. These drugs also are known to cause drops in good cholesterol.