16 years old should still be a student, don't take diet pills.
When sitting and studying, you can put a book or towel between your knees. Be careful not to let it fall. If you insist, you can stovepipe. Sit up straight, or you'll have a stomachache.
You can dance every day at home during the holiday, and you can also turn the hula hoop properly.
Get up in the morning and walk for 20 minutes, which is good for correcting your figure.
Eat more negative calorie foods such as spinach and apples.
Wish you success!