While not confined to locals, Qatar, like many parts of the world, has an obesity problem and with it the consequent health issues.
When I add a few pounds or kilos (which I have done since living in Doha) I notice as my clothes become tighter.
Qatari men wear the thobe and women the abaya. Both garments are loose. A few pounds gained will not be noticed as quickly as a tight pair of trousers, unless they have elastic waistbands.