Depends on how fast you run :)

According to [1] in terms of calories burned by a 155-pound person in 30 minutes:

Running at 5mph is equivalent to beach volleyball, ice hockey and basketball, at 288 calories.

Running at 6mph is equivalent to kickboxing, cycling at 15 mph, vigorously swimming laps or vigorous step aerobics at 360 calories.

If you're lucky enough to be able to run a 10mph for 30 minutes (which is fast) doing so is one of the fastest ways to burn calories, burning 562 calories. The only thing listed that uses more calories is cycling >20mph.

Of course, people with their weight under control have a much easier time achieving higher speeds - someone who weighs 230 lbs isn't likely to be running at 10 mph, and they'll probably hit their weight goal before they'll hit that speed.

I agree with you that, with 270 calories in a chocolate bar, it's easy for bad diet to undo the benefits of exercise.

[1] https://www.health.harvard.edu/diet-and-weight-loss/calories...