When travelling, you must make sure that you are carrying only the ‘most required’ things and dump the rest.
It is better to avoid plastic and carry reusables to reduce the waste. Consider carrying your own toiletries, reusable shopping bags, etc.
As a traveler, the choices you make, such as avoiding excess at buffets and packing your own food, can collectively contribute to mitigating the global 'food wastage' epidemic.