This is completely absurd in my personal experience. The amount of long duration, low intensity cardio I do has a massive effect on decreasing my weight with no dietary changes.
Beware personal experience. When I was in my 20s and 30s your statement was true for me as well. Now in the second half of my 40s, my body compensates for arbitrary amounts of exercise (HIIT+hiking) by increasing my appetite and I reliably weigh 20-30 pounds more than I did when younger. I briefly tried one of the medications mentioned in this article and it wasn't magic: all it did is make my appetite and metabolism operate more like it did when I was 20s/30s.