Anyone had irregular measurements?

Cally
At my 24 week scan the doctor decided I needed 2 weeks rest from work as the baby is 100g less weight than he ought be, his legs measures 24 weeks but the rest of his body measured 22 weeks and his head measures 21 weeks. I'm doing very little and upping my carbohydrate intake and not working means a lot less energy & stress (I'm a primary school teacher of 8year olds). Has anyone else had similar experiences? Does anyone have any tips?