I think I am going to have a discussion with my boss about their weight.
What is the point in you being concerned about the weight of your boss anyway?
The weight of their body harms their work performance.
I know that you want to help your boss, but telling them how to live their life regarding their eating habits is just interference. Let your boss make their own decision about their weight.
Fuck off, I know what I'm doing.
It may be a bad idea for you to tell your boss what to do concerning their weight and diet. This is most likely separate from work in your boss's opinion, so any advice may be seen as an intrusion or disrespectful.