Now the weight is under. For James Forrest, piling on the pounds and the performances is the priority.
While the Celtic team-mates of the 22-year-old not called up for international duty have been enjoying some well-earned down-time over the past 10 days, Forrest has been a man on a mission.
The pounds he shed while suffering from a virus which eventually saw him hospitalised for five days left him looking lean and mean when he eventually got back into action as a substitute in the closing stages of the Champions League tie against Barcelona.
His trademark darting runs were there for all to see when he replaced Adam Matthews after just 13 minutes of the SPFL game which followed.
But, to withstand the rigours of playing at the top level, Forrest knows he has to regain the strength and muscle bulk he has worked so hard to add to his skill and pace.
With a Group H double-header against Ajax set to kick off next week, the sooner he gets up to his best fighting weight, the better for everyone at the club where he is recognised as a key component of the system Neil Lennon wants to use in Champions League games.
Having already missed out on the trip to the San Siro on matchday one, the kid who scored the goal against Shakhter Karagandy which booked Celtic their place in the group stage - and the £15million that comes with it - is desperate not miss any more massive matches.
The sciatic nerve problem which flared up when he played for Scotland against Belgium at the start of September, and initially put him out of action before the respiratory virus struck, is now being successfully managed.
This has allowed Forrest to put in some heavy shifts at a near-deserted Lennoxtown since the squad broke up for the international break.
This tailor-made recovery programme will be stepped up this week as he awaits the return of team-mates, many with World Cup qualifier tales to tell.
Forrest would have liked to have been there to help Scotland try to bring their Road to Rio campaign to a happy conclusion with a win over Croatia tomorrow night.
However, he has had to accept getting himself fully fit for the games which really do matter must be the priority.
So, he has taken on board the opinions of those who have his very best long-term interests at heart, even if it meant missing out on another chance to play for his country.
Forrest said: "The club and the Scotland management team spoke about my situation, and they decided this was going to be the best idea.
"I am happy to go along with that. It means I can do some conditioning work over these two weeks and get back up to being fully fit again.
"I've just got my head down in training and got myself back up to speed."
That speed is what concerns opponents.
While Ajax's spies may have reported back to Frank de Boer that Celtic's only threat comes from Georgios Samaras, there are defenders across Europe who know Forrest's running power, crossing and willingness to shoot can also do serious damage.
It's a weapon Lennon knows is fragile, and he wants it to be ready to fire when it matters most.
For Forrest, however, every game is important, and building a trouble-free run of appearances is his major goal.
"I said before the season started what I wanted most of all was a consistent run of games, so it's disappointing to have missed a few already," said the likeable Ayrshire Bhoy who has played in 10 of the 17 matches Celtic have contested this season.
"But everyone gets ill, and there is nothing you can do about that.
"Hopefully that is out of the way now and I can get my strength and weight back up during this international break."
It does not matter he is now well-versed in how to deal with being laid up, the frustration of being unable to do the thing he loves most, playing football, still cuts Forrest to the core.
Lennon has taken him aside and made it clear that, while understanding how disappointed he is when he has a problem, in the long run, it is to everyone's benefit he is completely honest and tells the medical staff if he can sense even the beginning of a possible problem.
Forrest has taken that message on board, and, when fully packing the power once again, has his fingers crossed Lady Luck is going shine on him for a change.
"It was about four weeks I didn't play before I returned for the Barcelona game, and it is just good to be back out there," said Forrest, who is refusing to fall into the psychologically-harming trap of believing he is somehow jinxed.
"It always happens that you get bad luck in football. But hopefully I can have some good luck now and kick on."
Ironically, it was misfortune for a team-mate, Matthews, which gave him much more of a run out than he was anticipating against Motherwell in the match before the shutdown.
The Welshman's heavy fall left him requiring shoulder surgery and taking Forrest's place in the treatment room.
Having strength in depth is vital to Celtic's hopes of recovering lost ground in the battle to continue playing European football after Christmas, while also pushing on in the Premiership title race after finally overhauling Inverness at the top.
Forrest is confident they can overcome the loss of Matthews and Scott Brown, who is banned for the Ajax game, and maybe more.
"We've got a good enough squad with good enough players to deal with this and win most games," he said.
"We showed that coming off the Barcelona match to play really well against Motherwell a few days later. But we know we have to continue this form.
"I don't know why we are handling playing domestic games better this season compared to last year when we dropped points in games around Champions League ties.
"It's a bit of luck sometimes, getting some of the breaks you need.
"But all the boys are much fitter this year, and that's important as well."