我还没吃饱。

Use it when someone asks if you want more food. Or use it when the waiter tries to clear your plate. You can add 呢 at the end for a softer tone. 我还没吃饱呢 sounds a bit more natural in conversation. It is like saying 'I'm not full yet, you know?'

You can use this at a friend's house during dinner. It is perfect at a buffet when your plate is empty. Use it at a restaurant if the portions were tiny. It works well when someone asks 'Are you full?' (你吃饱了吗？). It is a very practical, everyday sentence for any mealtime.

Avoid saying this loudly at a very formal banquet. It might imply the host didn't provide enough food. Don't say it if you are trying to be extremely polite. In those cases, just say 'Everything was delicious.' If you are at a business lunch, keep it subtle. You don't want to look like you're only there for the food!

Food is the ultimate love language in Chinese culture. In the past, asking 'Have you eaten?' was a standard greeting. Being 'full' is a sign of a good life and hospitality. If you tell a Chinese grandma 我还没吃饱, be careful. She will likely bring out three more dishes immediately. It is a compliment to the chef in a weird way.

If you are really hungry, say 我一点都没饱 (I'm not full at all). If you are almost there, say 我还没完全饱 (I'm not completely full). For a very casual vibe, just say 没饱 (Not full). You can also ask others: 你吃饱了吗？ (Are you full yet?). It's a great way to show you care about your friends.