Ms Lamont puts her slimmer figure down to small steps and simple lifestyle changes.
She said: "I used to run. I ran a marathon and did a lot of 10Ks and half marathons, then my ankle went. The weight just crept on and got to the point where it was such a huge amount to lose, it was too hard to do it simply by not eating - I would have to stop the bad habits and get active."
For someone who had always been fit, rejoining the gym was simple.
Her son and daughter, Colin and Fay, swim and play netball respectively and she had been dropping them off at their local Glasgow Life gym and picking them up. She started arriving an hour early and going to the gym herself.
"Often I go out for a walk on a Sunday morning to Pollok Park or Linn Park - you don't have to go into a gym."
Watching Celebrity MasterChef while toiling at the gym sounds like torture but for the MSP for Glasgow Pollok it was the perfect antidote after a day in the Scottish Parliament.
"The gym and walking are good for my mental health. The job I'm in, there's a lot of pressure and sometimes your head feels as if it's exploding. I found with running that I'd write speeches in my head. I'd be worrying about something and by the time I'd come home, it would be written. All the stress just falls away."
She also started to watch her diet. Crisps, chocolate and biscuits were out.
She said: "I treated it the same way as when I stopped smoking in 1985. I just said, there are some things in this world I like but I can't have."
The only days she allows herself a treat are Christmas Day, New Year's Day and Easter Sunday.
She said: "The thing about being overweight and taking exercise is you are self-conscious - but I went to a Zumba class, which I loved, and I got a real sense of achievement from that."