You always need to drink water, but it can be especially important if you're trying to flatten your stomach.  When you drink water, you help your body maintain proper fluid balance, stop water retention (a major cause of bloated bellies) and feel full so you're inclined to eat less overall.  Water also breaks down fat for energy and moves nutrients to your muscles to maintain your metabolism. Add lemon, orange or cucumber slices to your water to give it a little flavor boost; you can also try herbs and flowers such as mint or lemon verbena. Among its many benefits, green tea can also lay claim to helping reduce belly fat thanks to antioxidants called catechins that it contains.  For extra fat-burning power, sip green tea before a workout. Smoothies are a great way to stay hydrated and can contribute to a flatter stomach.  When you make a smoothie with watermelon, you have the advantage of an amino acid known as arginine that's found in watermelon. A study in the Journal of Nutrition found that arginine can decrease body fat and increase lean muscle mass. A smoothie made with pineapple gives you the benefit of bromelain, an enzyme in pineapple that helps break down protein, ease digestion and banish bloat.  Watermelon smoothie.  Chop up two cups of watermelon and put it into a blender.  Add 1/4 cup of fat-free milk and blend for about 15 seconds or until smooth.  Add 2 cups of ice and blend for 20 seconds or until you get the consistency you like.  This recipe serves two. Pineapple smoothie.  Measure 1 cup of skim milk and put it in a blender along with 4 ounces of fresh or canned pineapple chunks.  Set the blender to "whip" and blend for 1 minute.  Pour into a glass and add 1 tablespoon of cold-pressed organic flaxseed oil.  Makes one serving. Ginger helps calm your GI tract and can help reduce bloating.  Add some fresh, grated ginger to your green tea or boil some chopped pieces of the root to make ginger tea. It's no accident that many restaurants offer diners peppermint candies after their...

TL;DR in Chinese:
将水当作主要饮品。 喝绿茶。 调一杯冰沙（又称思慕雪）。 摄入姜。 喝薄荷茶。 远离酒精。 远离碳酸饮料和发酵饮料。 不吃山梨糖 。