From my perspective, weight loss seemed like 90% diet once I got down close to the healthy BMI range. To be precise, I don't think I could have gotten into the healthy BMI range without controlling what I eat.

THBS, exercise was important. It just happened to be the side of the equation that came easier to me. Controlling the diet was the final piece of the puzzle I added to achieve success. Maybe diet was less than 90%, objectively; but it was the part I needed to pay attention to.

In the case of Matthew McConaughey, I'd guess that diet is at least 90% of the effort objectively and possibly more. That's because he is deliberately shrinking to an unhealthy low weight for a movie role. Absent having a real health problem, he won't be able to maintain that low weight without a really low calorie diet.

It's kind of the flip side of actors who put on 30 pounds for a movie role, except I think he'll find it easier to put the pounds back on than actors who add weight find it to take the pounds back off.

Patzer