I was already in the three digits when I fell pregnant (having never lost my pg weight from my DD1 9 years ago) and saw a dietician as I feared gaining the same amount again (and never losing it) and also I was worried about being high risk for GD. Basically she put me onto a low-GI diet, taught me about good portion sizes, and off I went. Couldn't do much exercise after the three month mark as I got SPD pretty badly and was in too much pain, but eating well I was able to limit my weight gain to about 10 kg. Three months post baby I've lost all bar 1.5kg and weight is still heading downwards thanks to good habits i learnt in pregnancy & breastfeeding.