That announcer should be done for hate crime in violation of the Disability Discrimination Act. 😱 What people fail to realise is that obesity (contrary to what the tabloid press would have us believe — a good rule of thumb is, if it's in a tabloid, it's more likely than not to be nonsense) is seldom self-inflicted; even if due to overeating, rather than to metabolic problems (and there's plenty of evidence that in many if not most cases, type 2 diabetes causes obesity, not vice-versa), that in turn is almost certainly due to mental health problems, thus still not self-inflicted.
Plus there's the fact that overweight people are more likely than thin people to suffer other disabilities such as mobility problems, and thus to need a seat. This is similar to the stupid (but able-bodied) woman I once overheard who objected to giving up her seat to an OAP because the OAP was (presumed to be) travelling on a free bus pass, and hence was "not entitled to a seat". 🙄 The idiot was too dumb to realise that (1) a bus (or train) fare, whether paid by you, your local council, your employer or whoever, pays for travel, and if you get a seat that's a bonus; and (2) those who are issued free bus passes (elderly or disabled) are precisely those who most need a seat (and, at least on London's buses and in the case of the designated "priority seats", are the only ones who actually are entitled to one). 😡