The most successful dieters are those who start slimming at the age of 28.
Women in their late twenties shed flab faster because they have more time and willpower than those of other ages, according to a survey.
Twenty-somethings are also more concerned about their weight and so remain focused on their weight loss goals.
By contrast, those in their 30s are often too busy to watch their weight while many in their 40s and 50s have simply 'lost interest' in getting the perfect body.
The study found women went on two diets or health kicks last year, spending an average of £131.57 on gym or slimming club membership and exercise equipment.
Despite this, almost three quarters admitted at least one of the diets failed.
Sue Beck, of Lambrini Light, which carried out the research, said: "With women getting married later than ever, many 28-year-old females will be single, on the dating scene and leading an active social life, which may explain why they are so successful at healthy eating and maintaining a good figure."
"Many will also be at the peak of their career, leading fast-paced lives which will help shift any excess weight alongside a diet."
The study of 3,000 women aged over 30 found that 64 per cent reckon there is a stage in their life where they are the best at losing weight. Four out of ten put this down to having strong willpower at that age.
Some 38 per cent in their forties and fifties reckon they have reached a point in their life where dieting and having the best figure was no longer a priority.
"It's inevitable that the older women get and longer they are in a stable, happy relationship the more comfortable they become with their body and embrace their curves," added Miss Beck.
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