File photo: Victoria Beckham reportedly followed the Five Hands Diet – eating only five handfuls of food a day – to slim down for New York Fashion Week two months after the birth of daughter Harper in 2011. Picture: AP

A mother's post-baby weight is due to her lifestyle choices and not the pregnancy, research suggests.

A study found that mothers keep weight on by eating food off their child’s plate or sitting down for longer periods.

They also suffer cravings as a result of sleep deprivation which can make them eat junk food even if they want a healthy diet.

If women want to lose the weight they should cut the calories and work out more. The study suggests that celebrity mothers who use expensive fitness coaches to get their figures back weeks after giving birth may be on to something. Michigan University researchers looked at data for 32 000 women who had given birth between one and four times.

All the women gained 1.94lbs (about 0.8kg) a year on average. But by the time their children were toddler age, the mothers had put on at least one pound a year more than childless women in a control group.

Lead study author Olga Yakusheva said that the difference was because "mothers tend to put the needs of their children first, so they might not be exercising or taking care of themselves". 

She said: "It might also be little things like finishing the food on their child’s plate or spending more time sitting with their kids ...

"Many women really crank up their diet and exercise for a short time to get back to their pre-pregnancy weight, and often get discouraged by the results.

"But it’s much better to take a holistic approach focused on a long-term healthy lifestyle before, during and after pregnancy."

Celebrity mothers have long drawn admiration – and criticism – for getting their figures back weeks after having a baby. Victoria Beckham reportedly followed the Five Hands Diet – eating only five handfuls of food a day – to slim down for New York Fashion Week two months after the birth of daughter Harper in 2011.

Professor Yakusheva, of the University of Michigan School of Nursing, said that during her first pregnancy she gained 70lbs and during her second 60lbs despite cutting calories and weighing herself daily. She said: "I felt terrible. Many women feel that anxiety about gaining pregnancy weight because they’re already anticipating pressure to lose the weight. Understanding the demands of motherhood and age-related weight gain is important for promoting positive expectations of body image after pregnancy. As long as women are healthy, that is what matters".

Miss Yakusheva said that doctors should advise women about age-related weight changes, and make them aware of subtle ways parenthood could exacerbate these. 

Erin Palinski-Wade, who offers nutrition advice on MommyhoodBytes.com, said: "After having a child, it’s not so much that you can’t lose the weight, but you may have less time to go to the gym, less time to food shop, and less time to prep healthy meals. Sleep deprivation itself can increase food cravings."