Something else that should always be considered, is OTHER things that are often done to make the "after" shot look better.
Do you ever notice that in the "before" picture, that the person often has pasty white skin...but in the "after" they have a nice, glowing tan???
Look at the hair, makeup, etc. as well. Often the person is made up to look nicer in the after.
There are also little tricks that they do to make the "before" look worse, and the "after" look better. They will often have the BEFORE shot taken with the person using VERY bad posture, and the AFTER shot is taken in a flattering pose, with tall, nice posture.
Look at the bikini photos! If the picture is taken in the same bikini, it will often be adjusted in a more flattering position for the after shot.
Start weight after baby #3: 233.9
Current weight: 143
90 pounds lost!