The survey by Forza Supplements showed that men and women in their 20s couldn't stick to diets due to too much partying.
However, 82% of people polled admitted that hitting 30 was a real lightbulb moment that made them want to kickstart a healthier lifestyle.
Women in particular found that getting married and having babies were great incentives to lose weight, as they don't go out and eat in excess anymore.
For women, the ideal age to start sticking to a diet was 32, while 31 for men.
Forza managing director Lee Smith said: "The ageing process starts to catch up with us all and both sexes are desperate to turn back the clock."
We'll have another slice of that pizza then.
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