(CNN) - In May, Sen. Claire McCaskill ( @clairecmc ) tweeted that she needed a change.
"I'm tired of looking and feeling fat. Maybe talking about it publicly will keep me on track as I try to be more disciplined. Off to the gym."
Her tweet was picked up by the blog Jezebel, which wrote that, "women, no matter what their role in public life, face a greater social penalty for being 'fat.'"
The Missouri Democrat tweeted later that day: "I just want to feel better, be in better shape. Healthier as I approach my late (gulp) 50s."
Her plan included healthy foods every three hours, cardio and Twitter.
"Of course there is the diet and exercise component," said her trainer, Charles D'Angelo. "What every program is missing is what holds it all together. It's like a stool - one being exercise, the other being diet. It's missing the third leg to keep the stool balanced. You have to hold yourself accountable. Claire used social media to keep herself publicly accountable."
So she told her 59,000 Twitter followers that she was struggling with her weight and planned to do something about it.
"That was totally Claire's idea," said D'Angelo. "Accountability is part of the mindset. You have to have something keep your accountable."
Five months after her first Tweet about her weight, McCaskill tweeted: "GOOAALLLLLLLL!! I did it! Lost 50 lbs. Thank you Team Charles and my new BFF... Mr Treadmill. Healthy food and lots of exercise."
The fact that a U.S. senator with a hectic schedule can find time to exercise, "blows the whole myth" that people are too busy to exercise "to pieces," D'Angelo said.
"We all have the same number of hours in the day. What I decide to do with those will bring about a result and consequence. That consequence can be a positive or negative consequence," he said.
Aside from her usual tweets about congressional committees, town hall meetings, Joplin, and the Cardinals, McCaskill occasionally posted updates about her fitness goal.
-- This will be a test. Can I be disciplined about healthy food choices in midst of family chaos? Typically food takes center stage. May 21st
-- Re: State Fair visit. Since I've been on this health kick I guess a funnel cake is out of the question? Aug 11th
-- It's official. I have divorced bread and pasta. I'm hoping someday we can be friends again. Sep 9
Using social media such as Twitter and Facebook to get feedback is a free tool to get encouragement and comments.
"Those two things, for free, you create an accountability group," D'Angelo said. "It's a wonderful tool to bring about unity. The comments, it only fuels the fire to keep with it. It's a wonderful tool to keep with a mindset."
There is no gee-whiz factor or magic potion in what McCaskill's trainer recommended.
He tells clients to exercise five times a week, from 30 to 60 minutes, doing something as basic as walking on the treadmill on a 4% incline.
D'Angelo bans caloric drinks such as juices, smoothies, soda and energy drinks. They are advised to eat three hours a day and D'Angelo puts them on a strict eating plan for the first two weeks.
Here's a sample menu:
6.a.m: breakfast with two eggs, piece of whole wheat toast, or a protein shake with whey protein and berries
9 a.m.: piece of fruit or one ounce serving of unsalted almonds
Noon: turkey sandwich on whole wheat bread with a banana
3 p.m.: low sugar yogurt
6 p.m.: lean meat or fish, green vegetable such as broccoli
9 p.m.: another piece of fruit
"The psychological part is taking away the variety so they are no longer spontaneous in their habits with food," D'Angelo said. "It's doable. It's not that hard. They start seeing results, feeling results and they're able to stick with it. It's reaffirming work."
After 14 days, the client gets more variety in his or her food choices. D'Angelo draws from his own experience, having weighed 360 pounds when he was in high school.
"The most important thing is getting to a place where they're holding themselves accountable," he said. "They're not trying to fill emotional sadness, boredom with food. It's making food as basic as hygiene, that this is what I do to fuel my body, to keep myself healthy."