The best workout isn’t necessarily the longest one: if you’re looking to boost your metabolism, then slash your rest time, say researchers from California State University at San Marcos.

They found that guys who rested for just 30 seconds between weightlifting sets burned nearly 10% more kiloujoules after their routine than when they rested for 90 seconds between sets. “Shorter rest periods make your muscles 
work significantly harder, which causes more damage,” says BJ Gaddour, training advisor.

“Then your body needs to do extra work to repair that damage,” which burns more kilojoules.