Fat people have more medical problems. Big bottoms are a drain on company bottom lines. Companies need to pay more insurance medical costs with fat, unhealthy employees in addition to having to deal with the lower productivity of those lazy workers. One solution is to just not provide insurance (my personal preferred solution and the one I use at my company), but this doesn't work so well with all companies. In those cases, it's best to have the company institute policies requiring that employees submit the height, weight, and bloodwork tests to the management. The company can institute a diet plan for the employees to follow to control their weight.
In my own company, this has worked spectacularly well. All of my employees are required to work 12 hour days, and work through all of their meals. When they are too busy working, they don't have time to stuff their faces. All the while, they are burning calories being productive. Consequently, my workforce is a lean productivity machine.