They will go a long way towards giving you a lean, healthy physique. And they're surprisingly easy to follow. Try some of them (or all of them) and see for yourself.
Prejudices against the overweight seem to develop early. One study found that children as young as three years of age believed fat people were "mean, stupid, ugly, and had few friends." People suffering from emotional distress in connection with weight problems are much less likely to succeed in their efforts to improve their health. For our society in general, a shift in attitude would help.