The latest Gym Bro pseudo-science has 2 schools of thought: One, is to do no cardiovascular (aerobic) training at all, it is unnecessary for fitness and fat loss; second, is to only use high-intensity interval training (HIIT) for cardiovascular fitness. Both of these schools fail. Cardiovascular endurance is one of the main components of fitness, as discussed here last week. However, cardio training should be performed correctly for maximum benefit. Read this article for tips to improve your aerobic training.
It seems popular lately to spread the idea that we do not need steady state cardio (walking, jogging, swimming, etc.) in order to achieve fat loss. Many a Gym Bro insist we only need to lift weights—the heavier the better— to lose body fat, claiming excess post-exercise oxygen consumption (EPOC) will do the trick. But these Gym Bros wrongly apply the EPOC science. Remember: you never see an overfat marathoner; but you see plenty of overfat lifters. Anyway, read this short linked first-person account of a fat loss journey involving cardio exercise.