Hi Noor. It’s a good point regarding bilious vomiting syndrome – for these dogs you will need to split the meals as much as necessary to prevent vomiting on an empty stomach. This just means that each meal can look ridiculously small, but that’s what you have to do.
As for the size of meals, read my article on how much should a dog be fed. However, in a nutshell it’s basically that you have to work it out by trial and error, and that food packets overestimate the amount sometimes by as much as three times what is actually needed.

Hi Kathy. Once a day feeding is fine for most dogs over 5 kg body weight but the amount always depends on what it takes to achieve the right goal, be it gradual weight loss or maintenance of a healthy weight.