I have been eating junk food for the past 7 years?

The key to good health is "everything in moderation". Although the diet foods you specified sound good, they may come as a bit of a shock to your body, especially as you've been eating junk for so long, and this could do more harm than good! Instead you should try gradually improving your diet, as this will allow your body to adapt to the changes, and will also make it easier to do one step at a time. :) good luck xx