The former Celtic, Aberdeen and Blackburn player, capped 44 times by Scotland, said: "I don't eat after eight o'clock at night.

"That is difficult when you have been training and naturally crave some carbs or a biscuit with your tea.

"I think everybody is the same and I just have to fight that back. I don't do that and I feel a lot better for that.

"I was a vegan for about two years and I found a lot of things beneficial from that diet.

"I learned that there is a lot of things you can do in that side of things but you need to get the protein on board which I learned.

"I have a certain diet now which is weird to people. I drink soya milk and eat chicken. It is about having a balance and I am at my best place now as far as diet and lifestyle is concerned.

"I feel as fit as I ever did and I eat better than I ever did so it is probably keeping me playing because as you get older you have to find things that give you that wee bit extra that maybe you never did in your 20s.

"Don't get me wrong, I am far from perfect but I keep striving towards being the best I can be."

After a 2-0 defeat by Aberdeen on the opening day of the season, United have beaten champions Rangers and double cup winners St Johnstone with a Premier Sports Cup penalty shoot-out win over Ayr United in between.

Mulgrew said: "We had a difficult start away to Aberdeen and we were really disappointed with that.

"So to respond with a win against Rangers and get through in the cup and beat St Johnstone last week, we take real confidence from the game.

"But at the same time we are not complacent. It is a decent start but those games are behind us and it is about Hearts now.

"It is going to be a difficult game for us, they will see it as a chance to get a result and we will have to match that."