Mrs de Jongh said the plight of sexual slaves was one that was particularly close to her heart.
"I've been to Cambodia several times, which is a country that has a lot of problems with sexual exploitation of women and girls."
She said in some cases girls were stolen from their families and locked in brothels, while in others families made the difficult choice to sell a daughter.
"As a mother myself, I cannot imagine what it's like to be in the situation where you may have to sacrifice one of your children so the rest can eat."
This is the second time Mrs de Jongh, who is a member of TEAR Fund, has taken part in Live Below The Line.
"I was surprised I wasn't hungry at all, but it is quite a challenge managing on $2.25 a day. You have to really simplify what you eat and I found myself feeling quite healthy because I wasn't eating any sugars.
"You become very mindful of every bite you take."
Mrs de Jongh's treat during the five days will be one coffee per day made of the cheapest brand of instant coffee she can find - which she estimates will cost her about 15 cents per cup.
But obsessing over the food was not the point of the challenge, Mrs de Jongh said.
"It's really about raising money and raising awareness of these women and girls who are being tortured every day."
-It's not too late to join Live Below The Line - it starts on Monday. Sign up at www.livebelowtheline.com/nz.