Many of us have heard the idea that doing cardio first thing in the morning on an empty stomach (commonly referred to as fasted cardio) will increase fat loss. It's worth keeping in mind that fasted cardio typically stems from the bodybuilding culture, where bodybuilders have low body fat levels. But for those of us who are neither lean nor overweight, is fasted cardio more effective than fed cardio? By fed, I mean that you're neither in a fasted state, nor still digesting your food.

Today on the podcast, I'll be looking at the work of James' Krieger, who is heavily involved in fitness-research and co-authored a study on the impact of fasted cardio on the body. James argues that in order to increase fat loss, fasted cardio has to do one of three things: increase energy expenditure, suppress appetite or spare protein. Does fasted cardio do any of these things? Tune in to find out. 

What you'll learn on this episode

• The three primary steps involved in fat loss
• How body fat is one of the determinants of whether doing cardio fasted will enhance fat loss
• Whether fasted cardio
  • Increases energy expenditure
  • Suppresses appetite
  • Spares lean muscle mass
• What the 24 hour energy expenditure is and why it's so important

Studies Cited in the Episode

• James Krieger's argument that there is no scientifically based reason why you should perform fasted cardio over fed cardio
  • Fasted Cardio...an Undeserved Good Reputation
• The process of fat loss and how body fat is a determinate of whether fasted cardio will work
  • Fast Cardio and Fast Loss - Q&A
• No difference in energy expenditure between fasted verses fed cardio
  • Effects of post-absorptive and postprandial exercise on 24 h fat oxidation
• When you perform fasted cardio you reduce your carbohydrate store around 18%
  • Exercise Increases 24-h Fat Oxidation Only When It Is Performed Before Breakfast
• Fed cardio suppresses appetite to a greater extent than fasted cardio
  • Appetite, energy intake and resting metabolic responses to 60 min treadmill running performed in a fasted versus a postprandial state
• Examination of protein oxidation rates
  • Effect of muscle glycogen on glucose, lactate and amino acid metabolism during exercise and recovery in human subjects