The 45 year old, who played football player Billy Bob in the teen drama, is in critical condition at a Dallas, Texas medical centre, according to TMZ.com.

Multiple sources tell the outlet he has been hospitalised for the past four months and has been progressively getting worse.

While it is unclear what he is currently suffering from, Lester was previously admitted to hospital in November (15) due to liver and kidney issues, and again in January (16), when he told TMZ he was having complications with his heart.

At the time, Lester joked about his medical condition and seemed to be in good spirits.

The actor has battled weight issues for years - around the time he starred in Varsity Blues alongside James Van Der Beek and Paul Walker, he weighed as much as 508 pounds (230kg).

He underwent gastric bypass surgery in 2001 and lost 350 pounds (158 kg).