To Rollsman,
Saving a jpg file after making some adjustments will inevitably cause some data loss, sometimes insignificant especially if you set the quality to 100, but data loss there will be. When you save your file in Portrait as a jpg the jpg algorithm will examine the file and compress it, trowing away data it considers unnecessary.
It appears that you are making portraits. Since you are already prepared to make adjustment in LR and in a portrait software you would be perhaps wise to use RAW files to begin with. Remember that a jpg file is a final product, just like a Polaroid print out of the camera. JPG have their uses of course, but your raw file is your original 'negative'.