Imagine you’re out for a walk in the woods. During this leisurely stroll, your muscles are using a type of muscle fiber called slow-twitch fiber. These fibers circulate the oxygen you take in, and with every breath, burn off blood glucose and the glycogen stored in your liver. You’re not breathing hard, but if you walk briskly for 20 minutes or more, you’ll begin to run out of glucose. To replace that blood glucose, your body taps into your fat stores.

Now imagine you hear a crashing noise behind you—it’s an enormous brown bear, out for blood. Suddenly you’re sprinting, and even though you’re fighting for as much air as you can get, it’s primarily stored sugar that’s propelling you. Your muscles are on fire as you burn glycogen like mad! Suddenly, the bear gets distracted by a school of leaping salmon, and you collapse safely in a heap. Your muscles probably feel like Jell-O, because you’ve burned all the sugar out of them.

If you start thinking about burning sugar when you exercise, and not about burning calories, you’ll see why short, high-energy bursts of exercise make more sense—you burn off the stored sugar in your muscles, causing your body to melt down fat in order to replace the missing glycogen.

The secret to cracking this seemingly impossible barrier: Exercise enough, but not too much. And here’s how it’ll happen: For six days a week, alternate between full-body toning and strengthening workouts (for 15 to 30 minutes) and cardio interval workouts (only 10 to 30 minutes). 

The former adds the muscle mass you need to burn more calories and includes three sets of eight to 12 repetitions of pushups, dumbbell squats, and other exercises. The latter mixes short bursts of high-intensity activity with lessintensity “recovery” periods, a routine that studies have shown targets belly fat.

Every day, do this simple and flexible one-minute-in-themorning energizer. This workout works with whatever energy levels you’re dealing with, getting you in the groove to move more throughout the day.

The all-out, 6-minute stationary bike workout

Directions: The three 20-second bouts of all-out effort, in between slow bouts of recovery movement, are all you need to gain significant physical benefits of exercise. You can also do the energizer on a treadmill or another cardio machine.

  • 2 minutes — Warm up, pedaling at an easy pace.
  • 20 seconds — Pedal as fast and hard as you can while maintaining control and good form. Don’t hold anything back. At the end, you should be huffing and puffing to catch your breath.
  • 90 seconds — Recovery movement. Slow to a very easy pace. Don’t stop. Keep pedaling slowly until your breathing returns to a comfortable rate. As you near the 90-second mark, start to ramp up your intensity again.
  • 20 seconds — High-intensity exercise.
  • 90 seconds — Recovery pace.
  • 20 seconds — High-intensity exercise.

That’s 6 minutes. You’re done!

Adapted from David Zinczenko’s Zero Sugar Diet: The 14-Day Plan to Flatten Your Belly, Crush Cravings, and Help Keep You Lean for Life (Ballantine Books)