Many people do not eat nearly enough fiber in their diets. In general, we should consume about 30 grams of fiber per day. I always recommend to patients that they try to consumer the latter amount, however, in general, I believe most people do not get more than 5 grams of fiber per day.
I recently read a great book called Transcend by Grossman and Kurzweil, in which they had a great quote about fiber. In this book, I will paraphrase that they report that for every one gram of fiber consumed, one can subtract four calories. The reasons for the this are very simple actually, we do not metabolize fiber (hence the frequent bathroom visits). The reason we can subtract four calories per gram is fiber decreases the glucose surge in our blood stream and in essence decreases the glycemic load of all foods consumed; this consequently results in a decrease in insulin release, which is needed to store sugars into fats such as triglycerides.
Fiber in essence decreases the amount of sugar in our blood, which leads less insulin resistance. This great consumption of fiber will eventually not only lead to less calories consumed, but one will also feel less hungry because the sugar levels in the body will be more stable. More fiber leads to less fluctuations in both sugar/glucose as well as insulin, which leads to less drops in sugar/glucose from an over production of insulin. These drops in sugar/glucose is what causes one to feel hungry.
Now that you are convinced that fiber is important for weight loss? What foods have lots of fiber. High amounts of fiber are found in Fiber One cereal as well as All Bran cereal. It can also be found in darker foods and whole grain breads, lentils, vegetables. There is no fiber in bananas, but some can be found in apples, this likely makes an “apple a day, keeps the doctor away” a somewhat valid statement.
In conclusion, I can reassure you that if you can consume 30 grams of fiber a day, some weight loss will be achieved. In 2 weeks, 30 grams a day would be equivalent to about 1700 calories of weight loss merely by subtracting four calories per gram of fiber consumed. This is equivalent to fasting for one day. Over time, this will add up.
references
http://www.transcendbook.com/