This is me.
I don't usually get in front of the camera these days. In 6 yrs I've put on 10kg. Yet incredibly in those years I have been pregnant 3 times and during each pregnancy I gained no weight nor lost any. Then during the short periods in which I breast fed I lost a couple of kilos.
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So by my amateur calculations I had 36 months in which to gain weight. That is 10 kilos in 3 years.