Start Our 21-Day Flat-Belly Challenge Whenever You Want!

Workout: Today's workout is 30 minutes of steady-state cardio followed by some serious ab work. Pick your favorite cardio — running, cycling, swimming, dancing — and keep moving at a steady pace for 30 minutes. Then strengthen your core and tone your abs with a 10-minute video featuring surprising variations of sit-ups and planks.

Recipe: Celebrate Summer and satisfy your sweet tooth with this grain-free crumble featuring blueberries, which studies indicate may fight belly fat. This dessert also features almonds; high in MUFAs (monounsaturated fats), almonds help burn away the fat that collects around your middle.

Get the details for Day 13 here.