Free Slim for Life by Jillian Michaels

of fat calories are used during low-intensity exercise, the total number of fat calories used during high-intensity training is greater because more overall calories are burned. Let me illustrate my point with two studies, one from the New England Journal of Medicine and the other from the American College of Sports Medicine (ACSM).
    The first study shows that a 200-pound guy who walks 3 miles per hour on a level surface for 60 minutes burns 5.25 calories a minute. Now, when the same guy jogs at 6 miles per hour for 60 minutes, he burns 16.22 calories per minute. Okay, let’s take a look at the math here. Jogging and working out at a higher intensity burned 975 calories compared to the 315 calories that he burned walking and working out a lower intensity. He burned 660 more total calories .
    In the second study, ten subjects exercised at a low intensity, walking 3.8 miles per hour for 30 minutes. They burned 8 calories a minute, equaling 240 total calories. Of the 240 calories burned, 59 percent (144 calories) came fromglucose and glycogen and 41 percent (96 calories) came from fat. This same group then exercised for 30 minutes at 6.5 miles per hour, burning 15 calories a minute. They burned 450 total calories, with 76 percent from glucose and glycogen (342 calories) and 24 percent from fat (108 calories). So they burned 210 total calories more (450–240) and 12 more fat calories, too (108–96).
    As you can see, even though the percentage of fat calories burned is higher during low-intensity training, during the high-intensity workout you’re burning many more fat calories and many more total calories overall.
    But wait—there’s more. What do you think happens to glucoseand glycogen calories that don’t get burned? They turn into stored fat. That’s why, at the end of the day, the main determinant of weight loss is quantity of calories burned, not the composition of the calories burned.
    My last thought on this, I promise. If you exercise at a higherheart rate and intensity, your body will burn far more calories long after that workout is over. This, as I mentioned earlier, is calledafterburn. One of the advantages of training at greater intensity, particularly withstrength training, is that it can boost your metabolism so that you’re actuallyburning more calories at a resting or base level. Your body becomes more efficient from training so you become a calorie-burning furnace—that’s the goal!
    As I mentioned, I want you working at 85 percent of your maximum heart rate while training. To figure out what this number is and how to attain it, simply plug your info into this simple equation:
    Subtract your age from the number 220. This will give you yourmaximum heart rate (MHR). So if I am 38, my MHR is 220 – 38 = 182. Then I want to work predominantly at around 85 percent of that number, except from when I throw myHIIT (high-intensity interval training—more on that soon) Interval into the mix (which works at nearly 100 percent MHR). So I multiply 0.85 times 182 and end up with 155 beats a minute. You don’t need a heart rate monitor to track this, even though it would be helpful. All you have to do is stop and count your heartbeats for six seconds during your training and then multiply by 10. I know that I need my heart to beat 15 to 16 times every six seconds to be at 155 beats a minute, working optimally at 85 percent of my MHR.
    Knowing your heart rate lets you become more familiar with what intensity it takes for you to optimally burn calories. If you want an easier way to track it: you shouldn’t be gasping for air while working out, but carrying on a conversation should be a struggle.
MIX IT UP • • 2 POINTS
    Don’t get stuck in a workout rut. Instead, mix up your workouts on a regular basis. Doing this provides multiple benefits. First, it keeps your mind from getting bored. Second, it keeps your body from plateauing for both physical performance and weight loss. Third, it’s critical for your