>>If you do HIIT you cycle as fast as you can for 10-15 seconds (or until properly worn out) then rest long enough to be able to do it again. You only end up working out for less than one minute or just half a minute in total but you get similar if not better results than the 45 minutes workout.

You will improve things like muscle buffer capacity and maybe VO2max (although for that longer intervals are much better) but those are not the most important things for metabolic health or health in general.

Recommending sprinting to untrained people is just a very bad idea. Fatigue and injury risk is higher. Benefits when it comes to metabolic health are lower.

It's important for exercise to be in heavy domain. Maybe it's a good idea to be in severe domain for a while (VO2max training) but typical HIIT hacks maximize pain/injury risk/recovery time while giving less benefits (unless you compare it to something silly like strolling for 30 minutes).