The universal first step for the treatment of diabetes mellitus, hypertension, dyslipidemia or atherosclerotic disease is therapeutic lifestyle change (TLC). However, in most cases, long-term sincere maintenance of TLC is very difficult. The Look-AHEAD study was initiated based on the results of the Diabetes Prevention Program (DPP) trial that evaluated the effects of TLC on the prevention of diabetes. However, the look-AHEAD trial failed to demonstrate the benefit of intensive lifestyle intervention (ILI) for the prevention of CVD or CVD-associated mortality. Several explanations were suggested, including that the ILI group did not maintain effective weight loss, and that the intervention and control groups both received the same high-quality medical treatments. The participants of the look-AHEAD trial were very highly motivated, and the investigators of the trial systematically pursued their patients to achieve the desired end result, which is quite different from the usual clinical practice setting. Simple advisement for patients to perform diet restriction and moderate intensity regular physical exercise typically fails and is ineffective for the prevention of CVD in actual clinical practice. Concomitant sincere control of other risk factors is necessary for long-term CVD prevention. Further research on practical and effective methods for achievement of successful TLC is needed. (J Korean Diabetes 2014;15:129-133)