James Sexton is the world's best divorce lawyer. This is the 'most outrageous' prenup he's ever seen.

James Sexton has been described as the world's "best" divorce lawyer, with more than two decades' experience practising law.

He's seen both sides of the coin in divorce and family law, and is the author of two books about maintaining a happy marriage and avoiding divorce. Essentially, he's seen it all, including some pretty shocking prenuptial agreements — one of which sticks in his memory as the "worst" he's ever seen in his career.

Watch James Sexton talking about the worst prenup clause he's ever seen. Post continues after video. 

"[The prenup] had a provision that said that for every 10 pounds [4.5kg] the wife gained in the marriage, she would lose [AUD$15,000] a month in alimony," he explained to Steven Bartlett's Diary of a CEO podcast.

This incentive came down to the client's "concern" that his wife might "become less attractive" as he got wealthier and she got older. 

As such, she was required to weigh herself regularly so a record could be kept in case the couple were to divorce.

Despite the request being both disturbing and inappropriate, Sexton said the clause was questioned in court to make sure both the wealthy client and his then-fiancée knew what they were agreeing to. 

"The court said, 'This is a disgusting provision. I don't know why you married this person,'" the lawyer recalled. "But it's enforceable. It's a contract. The two of you signed it and you had a right to sign it and you agreed to these rules, and they may be ridiculous rules but you agreed to them. And you have a right to do that."

While Sexton felt the provisions of the prenuptial agreement were "very shallow", when asked if he thought the couple were in love, he said there was also "something very honest" about the clause.

"He was making very clear and putting it in writing: Here's the value you bring to this relationship. I consider your physical appearance vitally important to this relationship," he said.

"But let's not forget the other side of the equation. She was going to get $70,000 [$105,010 AUD] a month, that's a very impressive number, so I think she also understood there was a value to be attached to him as well."

While the prenup may seem outlandish (and, um, kind of gross) to many of us, Sexton explained that, as a lawyer he's not there to comment on whether an agreement such as this constitutes love. Rather, he looks at "the engineering" of prenups.

Had he been representing the wife in the case, he continued, he would have advised her to put on weight before the wedding to ensure her 'base' weight was as high as possible. If the couple were to separate, he would then have her go on a strict diet, wear light clothes on weigh-in day, do regular sessions in the sauna — whatever it took to shed weight, making sure she got as much money as possible.

"That's why lawyers don't get invited to parties, because that's how we analyse problems," he said. 

"Like, I didn't hear that and go, 'What is the nature of their coupling?' I looked at it and went, 'I could play with that.' Whoever I'm representing in that transaction, I can figure out a way to make that work."

Feature Image: The Diary Of A CEO.