According to an article in the May 1, 2008 edition of the New England Journal of Medicine, overweight and obesity are associated with hypertension, glucose intolerance, dyslipidemia and obstructive sleep apnea. Obesity is associated with increased risk of death from cardiovascular disease, diabetes, kidney disease and obesity-related cancers. The rate of diabetes has more than doubled in the last 30 years.
By being active - walking and using stairs instead of the elevator, and starting a formal exercise program, you could very easily burn 300-500 calories a day. You would need to cut 300 calories per day to lose one half kilo per week. Aerobic exercise will also greatly improve your cardiovascular health and resistance training will raise your metabolic rate.
It is important to practice good nutrition, portion control and a balanced exercise program, but without basic behavioral changes, such as done at the Lose It! Center for Weight Loss, much of the effort made will not be internalized and will not bring good health.