You'd have to lift with no rest between sets to achieve that. Let's say you perform 30 total sets in 60 mins with 3 mins of rest between sets. That gives you only 20 mins of actual work time. No way you can burn 400 kcal like that.
But you don't magically stop burning calories in rest phases.
You also don't stop burning calories when you sleep.
@Stonehedge started
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You'd have to lift with no rest between sets to achieve that.
Let's say you perform 30 total sets in 60 mins with 3 mins of rest between sets. That gives you only 20 mins of actual work time. No way you can burn 400 kcal like that.