They should have checked your BMI during your medical. If it's to high then they may ask you to put your process on hold and 'lose your excess body weight' it's the same If your BMI is to low they ask you to gain weight though. Dependant on who you have. For my medical I was 18.1 on my BMI and he didn't question it but some can ask you to pause the process and redo it at a later stage. Just have to weight yourself and see if it falls within the 'healthy' bracket.