United Kingdom, Sept. 1 -- Brian Austin Green has started "losing" his sex drive as he's gotten older.

The 53-year-old actor, who has Kassius, 24, with ex-girlfriend Vanessa Marcil; Noah, 13, Bodhi, 12, and nine-year-old Journey with ex-wife Megan Fox; and Zane, four, with fiancee Sharna Burgess, believes it is very normal for men's desire to have sex to decrease as a result of a "chemical thing" within their bodies.

Speaking on his I Do, Pt. 2 podcast, Brian read a listener's question before giving a candid answer.

He said: "As men age, do you notice that your sex drive is lowering?

"Sure. Absolutely. Of course.

"That is a chemical thing. That is testosterone, and that is what men, as they age, start naturally losing. You can take s...