Concerning togas, Wikipedia says: "it was hard to put on, uncomfortable and challenging to wear correctly, and never truly popular. When circumstances allowed, those otherwise entitled or obliged to wear it opted for more comfortable, casual garments. It gradually fell out of use, firstly among citizens of the lower class, then those of the middle class. Eventually, it was worn only by the highest classes for ceremonial occasions, and by the 5th century AD, it had been replaced as official costume by the more practical pallium and paenula."
And "It was considered formal wear, and was generally reserved for citizens."
One story suggests that even patricians, no longer in office, did not wear togas all the time:
"Various anecdotes in Livy's history of Rome reflect the toga's symbolic value. In one, the patrician hero Lucius Quinctius Cincinnatus, retired from public life and clad (presumably) in tunic or loincloth, is ploughing his field when emissaries of the Senate arrive, and ask him to put on his toga. His wife fetches it and he puts it on. Then he is told that he has been appointed dictator. He promptly heads for Rome.[34] Donning the toga transforms Cincinnatus from rustic, sweaty ploughman – though a gentleman nevertheless, of impeccable stock and reputation – into Rome's leading politician, eager to serve his country; a top-quality Roman."
By comparison, the entry for "tunic" says: "The name derives from the Latin tunica, the basic garment worn by both men and women in Ancient Rome, which in turn was based on earlier Greek garments that covered people around their waist." The Greek garment was called a chiton.
You may also be interested in a sarong, or related clothing like a dhoti, lungi, mundu, or lava-lava. Some of the pictures from those pages shows men who are chubby around the middle.