I admit this not a practical situation I'm currently facing, nonetheless I've been wondering about this for quite a long time already.
Salad Story is a food chain somewhat similar to Subway, except that instead of sandwiches they serve salads. Like Subway, SaladStory establishemnts have a long counter divided into sections and when a client orders a salad an employee will assemble the ordered dish, gathering ingredients from shelves under the counter. If there are many clients in the same time and multiple employees are serving clients simultaneously then many employees may need to access the same section (eg the secion with vegetables) at the same time.
As a customer I was looking with curiosity at one certain obese employee. She was serving clients as well as any other employee, but then I tried to imagine how many employees can, at the same time, gather vegetables from that section of the counter. I concluded that four of the thin people working there could fit at the same time; if the fat one was there then only two other thin people could fit; and if there was another employee that fat then only two of them could serve vegetables at the same time. Basically, that fat employee had the size of two people of normal weight.
At the local bakery and confectionery store I saw a similar situation. Out of all employees working there one was very obese and another one was somewhat overweight. I saw they had trouble passing each other when they were both working behind the counter. So this was not only my imaginary problem, but it seemed to me (as a customer) that this was a very real problem that stemmed from these two employees size alone.
Assume that an employee at such a gastronomic establishment is otherwise flawless. They have no trouble at physical work such as sweeping, mopping, walking from section to section to serve customers; they are friendly and customers like them; nonetheless the employees obesity means that their size alone (rather than any other possible issues) becomes problematic.
Can, in such a situation, the employer request that the employee loses weight? Or would such a request be unacceptable from the employer?