McCaskill began tweeting in May about her desire to "be more disciplined" and hopes that speaking publicly about "feeling fat" would help her stay motivated.

"It meant that people were going to be watching to see if, in fact, I stayed on track, if I actually made that commitment to work out every day of the week and to really be accountable," she said Wednesday. "And so, when I hit that send button that day, I knew that there was no going back."

McCaskill announced earlier this month that she has reached her goal loss of 50 pounds, but pledged Wednesday to keep working out in order to avoid the embarrassment of going "back to my old ways" after getting healthy.