According to Men’s Health magazine
Varying training intensity with intervals ALWAYS beats out steady pace jogging. Workouts incorporating short spurts of cardio with periods of strength-building, enhances endurance and trains your body to recruit more muscle, boosting your metabolism and burning more calories all week long.
Australian researchers found that women who alternated just 8 seconds of high-intensity exercise with 12 seconds of low-intensity activity for 20 minutes, 3 times a week, slimmed down faster than steady-paced exercisers who worked out twice as long. Those who did intervals lost up to 16 pounds, shrunk their bellies by 12% and their thighs by 15%, and gained, on average, 1 1/2 pounds of metabolism-revving muscle in 4 months—without dieting!”