>You can't outrun a bad diet.

You certainly can. If you eat Mcdonald's every day, that's a bad diet, and if you just sit around all day, you will gain weight. But the same person that eats the same exact McDonald's meal every day but also walks for an hour a day is going to be thinner. The real myth being perpetrated on this thread is that if you start walking an hour every day that somehow you will started eating more and that the only way to lose weight is to change your diet. This may be true if you eat a giant box of oreos every few hours, but it is certainly not true just because you have a "bad" diet. Eating healthier food is a good idea and I certainly recommend it, but it seems to me that the refusal of so many to accept that daily exercise in itself can lead to a healthier weight is a sign of denial by the overweight.

A Big Mac is over 500 calories.

Running, not walking, only burns around 500 calories an hour.

You can eat a Big Mac in 5 minutes and it'll take you an hour of running to burn it off.