Analysis by Million Dollar Woman shows that if a 9-month-old baby weighs 10kg and is picked up and put down around 90 times each day, it adds up to a whopping 900kg of lifting across a day for that mum.
"When you factor in up to five feeds a day, two naps, a night time sleep and lifting your child for playtime and around the house, the weight really adds up," Million Dollar Woman CEO Lynette Argent said.
"We all know parents with young children are often tired, and we put it down to lack of sleep, but perhaps it is also the solid weights workout they get on a daily basis.
"Who would have thought stay-at-home parents lift the equivalent of one tonne, or a baby elephant, every day or so?"
"We all know that full-time mums with young children have tremendous demands on their time, which may prevent them going to the gym or working out," she said.
As a result those in the workforce fulltime spend 161 per cent more each year on maintaining their fitness than parents in the home, Ms Argent said.
"On average, stay-at-home Australians spend $148 a year on health and wellness, compared to $386 for full-time workers."