HIIT, or high-intensity interval training, consists of multiple exercises of different intensities with intervals of rest. A typical session lasts 15-20 minutes but is more effective for fat burn than running for 30-40 minutes, with a fat loss efficiency at least twice that of running. Here's a 15-minute HIIT training plan: 8 exercises, 40 seconds on, 20 seconds off, two sets. Before that, warm up for 5 minutes with 2 sets of warm-up exercises.

Now, let's dive into the HIIT workout:

1. Jumping Jacks: Keep your body relaxed, jump with knees slightly bent, and breathe evenly.

2. Butt Kicks: Keep your back straight and kick your heels towards your glutes with moderate force.

3. Lunge with Twist: Keep your back straight, knees behind toes, and twist your upper body. Repeat on the other side in the second set.

4. Jump Squats: Keep your back straight, jump with balanced coordination, and land with slightly bent knees.

5. Mountain Climbers: Keep your back straight, distribute your weight evenly, and maintain a straight line with your body.

6. Jumping Rope: Perform a continuous motion with coordinated movements, landing with slightly bent knees.

7. High Knees: Keep your back straight, raise your knees with your toes and knees facing forward.

8. Russian Twists: Keep your back straight, move your upper body downwards while swinging your arms naturally.

Finally, finish with a plank exercise to strengthen your core. By following this plan regularly, you can burn fat efficiently, even in the winter.