Effortful physical exertion has many benefits (not walking or slow jogging, but heavy exertion) and should be pursued by anybody who desires to stay fit, but weight loss can only be achieved via diet. That means no carbs. It is settled science...
To Lose Weight, Eating Less Is Far More Important Than Exercising More
We take it for granted today, but it is an astonishing fact that, at least in the Western world, one of our challenges is dealing with too much cheap good high-caloric food. For regular folks, that's a first in human history.