This indeed makes it harder. If I wok some dish for 4 people and use 1 tbsp of olive oil, did I consume 1/4th tbsp? What if 2 of those 4 were kids, so I ate slightly more than 1/4th?
I'm assuming we're talking about e.g. rice dishes or stews, curries, etc. "one pot" dishes. Otherwise if it's like steak and vegetables, you can weigh each steak and the vegetables, do them in different racks of a steamer etc.