I think many people are much more comfortable and capable of donning/doffing their weighbelt if they carry something like 6-9 lbs on the belt. All other weight someplace else (many suggestions above) or in some other form (steel tanks/double tanks/etc). All you need on the belt is enough to make you positively bouyant, and a lighter belt will be much better for your back and much less determined to slip. Even if it does get loose at depth, a 6-9 lb belt is hugely easier to tighten than one it takes real strength to control.
A fabric ("soft") belt with lead pouches also may be more comfortable and stay put better - but even a soft belt is nicer if 9 lbs or less. It's really nice to have a belt you can manage with one arm, even swim holding it in one hand if necessary.
I also find have to suspect that 40 lbs mught be more weight than you really need. When I started diving I was quite overweight and had a 7mm suit + 5mm oversuit, but I still never used even 30 lbs of lead. Try checkinging your weighting and be absolutely sure you are getting all extra air out of both suit and BCD.
A fabric ("soft") belt with lead pouches also may be more comfortable and stay put better - but even a soft belt is nicer if 9 lbs or less. It's really nice to have a belt you can manage with one arm, even swim holding it in one hand if necessary.
I also find have to suspect that 40 lbs mught be more weight than you really need. When I started diving I was quite overweight and had a 7mm suit + 5mm oversuit, but I still never used even 30 lbs of lead. Try checkinging your weighting and be absolutely sure you are getting all extra air out of both suit and BCD.