Rather than a long and low-intensity cardio workout, try the HIIT method of cardio: intense, fast-paced intervals that leave you completely exhausted after only a 20- to 30-minute session. This form of cardio training increases the afterburn effect, allowing your body to continue burning calories long after your workout is over. You can rotate between 30 seconds of your favorite exercises, with rest in between, as long as they work different muscle groups—such as squats, push-ups and kettlebell swings.
The prevailing formula for a long time on how much fat you’re going to burn was calories in minus calories out, based on your basal metabolic rate (BMR) and exercise efforts, explains strength and performance specialist Joel Seedman, Ph.D., owner of Advanced Human Performance in Atlanta. But with all the different biochemical reactions in the body, hormonal response, and endocrine function, there are an infinite number of factors that can affect how your body is storing and breaking down calories.