"Exercise" in these studies could be something like leisure walking for a couple of hours. That can only affect your weight by keeping you away from your snacks for a couple of hours, its energy expenditure is not moving your weight in any direction. If you look up, the energy cost of light activity is exaggerated. You can get numbers as high as 1 kcal / (kg*km) so somebody who is 100kg (220lbs) supposedly burns 500 kcals in a 1 hour of walking at 5 km/h (20 minutes mile). I know people who believe these numbers, think themselves at a caloric deficit and, when still gaining weight, doubt the Thermodynamics instead of the exercise "science".