According to a new survey women are most susceptible to putting on weight at 30, the average age for first time mothers in the UK.

They go on their first diet at the age of 19. A diet typically lasts for four weeks and three days. They will diet on eight separate occasions in their 20s and six occasions in their 30s - losing an average of 3 stone by the time they are 40.

The average weight of women in their 20s is 10st 7lbs and 11st in their 30s. The results are revealed in a new survey of 1,000 women by Britain's leading diet firm which details the dieting milestones throughout most women's lives.

It revealed that women find it easiest to lose weight in the 20s when they have more free time and the spare income to afford membership of a gym.

They are also more likely to be single and keen to maintain their figure to meet a partner. The peak age for losing weight was 25 - the same age Harry Potter actress Emma Watson and the Hollywood star Jennifer Lawrence.

The peak age for putting on weight was 30 - the same age as the singer Lily Allen and the actress Carey Mulligan. This could be related to the fact that the average age for first time mothers is now 30.2 years, according to the Office for National Statistics.

The survey found that first-time mothers typically put on 4lbs. Only a third (32%) have managed to lose that weight a year after the birth. This may also explain why the average woman in the UK puts on 7lbs between her 20s and 30s.

Lee Smith, managing director of, said "Our research shows the battle to lose weight gets harder for women as they move from their 20s into their 30s. They have less free time to go to the gym and may well be struggling to lose the weight that they put on after having children."

"They are less likely to diet because they are juggling so many other things in their lives and are more likely to need help in losing weight."

Women's Dieting Milestones

1. First diet - aged 19

2. Average duration of a diet - 4 weeks and three days.

3. Peak age for losing weight - 25.

4. Peak age for putting on weight - 30.

5. 4lbs - average weight women put on after having their first child.

6. Eight - number of diets women will go on in their 20s.

7. Six - number of diets women will go on their 30s.

8. 3lbs - average weight loss during a diet.

9. 3st or 42lbs - average dieting weight loss of women up to the age of 40.

10. Women typically put on 7lbs between their 20s and 30s.

Women are most likely to put on weight when they reach 30

Women are most likely to put on weight when they reach 30

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