Yes...you can have a BMI of over 40 and hold a Class 1 certificate....
This has been canvased before....BMI 30 or under you get no hassels from the CAA..over 30 BMI well depends on them what they do next...
What they usually do is to get you to go to a cardiologist and do a stress ECG....then get a report from him...then your TRI or E will have to get you into the cockpit and make sure you can demostrate that you can handle all the controls normally and can perform emegency procedures without any problems....
So after all that...they just pass you and you have your Class 1...so they just give you a hard time until you get to 30 or under on the BMI reading...
I know...as I have this problem...got to stop drinking beer and red wine...and I love my food....need more excerise I guess......darn it!!!....