Matthew McConaughey, star of “Dallas Buyers Club,” revealed how he lost 50 pounds for the part.

His odd diet consisted of only fish, egg whites, tapioca pudding, and “as much wine as I wanted to drink.”

“I did not subject myself to agony. I was a fighter. The most difficult thing was making the darn decision,” McConaughey stated on an episode of “The Joe Rogan Experience” that aired on October 22.

Ron Woodroof, played by McConaughey, was diagnosed with stage 4 HIV/AIDS in the mid-1980s.

As he detailed Woodroof’s life and legacy, the actor told Rogan that he wanted to lose all of his weight to convey the realities of living with advanced stages of HIV.

“It was my fault,” McConaughey admitted. “You’d be out of the movie the first frame if I looked like I do now and played Ron Woodroof from ‘Dallas Buyers Club.’”

In five months, McConaughey dropped from 188 pounds to 135 pounds.

To stay trim, the actor ate small portions of fish, vegetables, tapioca pudding, and egg whites and rarely exercised.

The actor stated that for lunch and supper, he would have 5 ounces of fish, tiny portions of vegetables with each meal, and egg whites for breakfast. A modest quantity of tapioca pudding would be his daily indulgence.

“I found tapioca pudding, and I found the tiniest little antique spoon in New Orleans, a little-bitty sugar spoon, and I would eat it with that so it would last longer,” McConaughey told a crowd of reporters at the 2014 Screen Actors Guild Awards.

Dietitians frequently recommend fish as a lean source of protein for persons trying to reduce weight. Vegetables are also considered one of the best weight-loss foods, as they are a low-calorie source of fiber and nutrients.

Jumping from the calorific diet, McConaughey was likely eating to build muscle for his role in “Magic Mike” (which required washboard abs) earlier in the year. This low-calorie diet would also have dramatic results.

The actor also rarely exercised during his preparation for “Dallas Buyers Club,” as it seemed to make no difference in his weight loss. Cutting out muscle-building workouts like lifting weights can decrease your muscle mass, leading to a drop in weight on the scale.

“It didn’t matter if I was going to the treadmill and burning 2,000 calories a day or not, 2.5 pounds a week,” McConaughey said.