Food waste is a global issue, since one-third of food produced for human consumption is being wasted. The United Nations has established a goal to reduce food losses by 50% by 2030. The food service sector is the third largest contributor to food waste. Plate waste is significant for reduction efforts, as it is largely considered avoidable. Minimizing plate waste can decrease overall food waste, providing environmental and economic benefits.

This study was conducted in Northern Portugal over a period of 1 month and 2 weeks, with data collected over 2 weeks (10 days) in each of the three restaurants (n=3) during lunch periods. The focus was on "daily" meals, which are affordable weekday lunchtime meals varying daily, with both meat and fish options. In total, waste from 152 meals (76 meat, 76 fish) in restaurant 1, 175 meals (99 meat, 76 fish) in restaurant 2, and 244 meals (189 meat, 55 fish) in restaurant 3 was assessed. Portion servings and plate waste were measured using a Baxtran® scale with a 3 kg capacity. Each day began with noting the menu and preparing for waste evaluation. Plate waste was categorized into protein-based, carbohydrate-based, and vegetable-based waste, then weighed and recorded at the end of the day. Non-consumable leftovers such as bones and peels were excluded from the measurements.

This preliminary study revealed that, despite serving portions being 43% smaller than those in other studies, the plate waste remained similar. This indicates a higher relative plate waste in comparison to the initial portion size. Carbohydrate-based foods were the most wasted, with 19.1% of these foods left uneaten. Additionally, some meals were less favored by customers, leading to higher plate waste (e.g., 32% waste on Monday), highlighting the need to re-evaluate the menu. This study also identified challenges, notably the restaurant staff's reluctance to accommodate external researchers. This highlights the need for greater awareness of the economic benefits of reducing waste and improving customer satisfaction.