70-year-old boss oinks at expecting employee after she ate a cheeseburger for lunch: 'She's eating for two and even if she wasn't, let the woman enjoy a burger!'

In what world did he think that this was an appropriate comment to make? 

When is it appropriate to talk about diets with others? I'd argue it's a good rule of thumb to never mention how much, how little, or what your coworker is eating. It's none of your business what they eat, and they might have the diet they have for a good reason! Maybe they're trying to gain weight after a period of being underweight, so they eat as many peanut butter and jelly sandwiches as they can. They might be on some crash diet that involves only eating brown rice and vegetables, but it's not your place to tell them that such a diet is probably not sustainable. You can be much more candid about your food choices with your close friends and family, but it's kind of gauche to talk about your uber-restrictive diet with your coworkers. You have no idea if one of them has struggled with eating problems in their past or present, and you don't want to make the workplace uncomfortable for anyone.

There's a difference between saying, "I'm such a pig, I ate so much today," and "You're such a pig, you ate so much today." You might feel uncomfortable if someone says the former, but it's not like it's a direct attack on you. The latter is so unthinkable and socially unacceptable that you'd think it would be completely extinct in all social situations. The only exception might be certain toxic mothers speaking to their daughters behind closed doors. But surely, that wouldn't be said in a professional setting today, right?