Nutrition is such a complex topic, and there are a lot of things we don't yet know or understand. There is one topic though that almost all nutritionists agree on, and that is the fact that we don't get enough fiber in our diets. A person who eats a diet rich in fiber has a reduced risk of heart attack or stroke (almost 40% lower according to some studies), is less likely to be obese, and has lower risk of diabetes among a lot of other benefits.
If you need to lose weight, adding extra fiber to your meals helps you to feel full longer and can make it easier to stick to a healthy diet. Some experts recommend trying to reach 40g of fiber per day, which is a lot unless you load up on some of the fiber packed super foods below.
Raspberries - 8g per cup
To save some money head to the freezer section of the local bulk store, the berries have the same fiber and nutrients as fresh but are much less expensive.
Pears - 6g per medium
Easy to pack for lunch and tasty as well, pears are a great choice for fiber and also supply vitamins A and C.
Avocado - 14g per medium 
The avocado is a super food. Loaded with nutrients and heart healthy monounsaturated fats, the avocado packs in 14g or fiber and more potassium than bananas.
Navy Beans - 10g per 1/2 cup
Looking for the easiest and least expensive way to eat healthy? Add more beans and legumes to your diet. Beans offer more protein and fiber per dollar than any other food on the planet.
Flax Seed - 6g per 2 tbsp
You can use a coffee grinder to grind flax seed and sprinkle it over toast, yogurt, into oatmeal or a salad. It has a slightly nutty flavor and adds a lot of Omega-3 to your diet as well as the fiber.
One word of caution for the fiber challenged. If your diet is mostly Twinkies and McDonald's right now (meaning no fiber), don't jump to 40g a day or you are going to be mighty uncomfortable and people won't want to sit next to you on the bus. Take a couple weeks to ramp up and allow your body to become accustomed to the new fiber in your diet!