Disclosure, I'm fat. Just over 300lbs. I've never noticed any "discrimination" that wasn't based on a reasonable necessity, such as rides I couldn't ride due to restraints not fitting or weight limits for safety. I've never even been asked my weight in housing. It may be true obese women learn less on average, but if you have to work with clients/customers, fair or not, attractiveness factors into it. And there's nothing the employer can do about it. People are more likely to buy from attractive people and tip attractive people more.
Side note: tipping culture allows discrimination in various categories and allows sexual harassment to thrive, by putting the onus of fair pay and treatment directly on the customers, rather than the employer.