So you didn't outrun a bad diet. You counted calories and matched your diet to your exercise (or vice versa) to get the weight outcome you wanted.

I think some here are narrowly interpreting "bad diet" to mean "lots of junk food". While yes, that's not a great diet, what's really meant is a diet where calorie intake regularly exceeds expenditure, regardless of what you're eating.

Even if you eat only the healthiest of foods, if your intake is too much for what you're burning, that's still a "bad diet".

I don't think that's a reasonable way to define the phrase. If "bad diet" is defined in terms of how much exercise you do, then "you can't outrun a bad diet" is a tautology.