No exercise is better for weight loss and health improvement than high-intensity interval training (HIIT), which is why LEAN Keto focuses on it.

HIIT is a type of cardio during which you alternate between bouts of strenuous efforts on a speed-based movement and active rest periods. 

For example, you switch between sprinting on an exercise bike for 30 seconds and slowly peddling for 30 seconds for a total of 20 minutes. (If that seems too intensive, do not worry – you will find a progression model later in this chapter so that you can build up gradually.)

Why would you want to focus on HIIT rather than on other exercise forms, say, steady-state cardio or resistance training? The primary reason is that HIIT is superior for fat loss.

This was clearly demonstrated in research at the Laval University.

In the study, scientists divided 27 subjects into two groups. Group one did a 20-week steady-state cardio programme, while group two followed a 15-week HIIT programme consisting of 15 sprints of 30 seconds. The results? At the end of the study, the HIIT group had lost nine times as much fat and lost 12% more visceral belly fat! That was despite the HIIT programme being five weeks shorter in duration. 

What is more, HIIT is the best form of exercise for managing diabetes. A meta-analysis of 50 studies established that HIIT reduces blood sugar levels and is more effective at improving insulin resistance than traditional continuous exercise.^[14] Therefore, HIIT is particularly useful for those with type 2 diabetes or at risk of developing the condition.

But that is not all. HIIT also has benefits for muscle mass, which helps you tone up your body. (Steady-state cardio, on the other hand, can hamper muscle mass.) The reason why maintaining or even gaining muscle is important while losing fat (as you will on a keto diet) is that it supports metabolism. In other words, the more muscle you have, the higher your metabolic rate, and thus the easier it is to obtain and maintain healthy body weight.