The human body is a wonderfully self-regulating system. We have mechanisms in place that, when allowed to work properly, cleanse our systems internally via systems of irrigation and probiotics (good bacteria). If you eat a proper diet including plenty of water and fiber, your colon should have no problem cleansing itself.
Since most of us have some imbalance in the bacteria, and most Americans do not eat enough fiber or drink enough water, we do feel blocked up. Colonic irrigation will indeed give you a temporary sense of well being after the treatment. You will feel “cleaner” and probably have more energy due to the sudden flow of blood around the colon. But this feeling is not permanent.
In addition, like a broad spectrum antibiotic, colonic irrigation tends to get rid of all bacteria, both good and bad, leaving the digestive system in worse state than before the treatment. Plus you can have complications such as rectal tears, which nobody wants.
The best thing you can do for weight loss is eat nourishing food in smaller amounts, drink plenty of water, and move as much as possible. There are no short cuts!