A group of friends become curious about the sustainability of their eating regiments. They instigate a challenge, and send filmmaker Yasi Gerami off on a quest to investigate the sustainability of their eating ideologies. The friends come from different backgrounds and live in Toronto, Canada, but the inquiry takes the story of their food around the globe. As Gerami digs deeper, she realises the inconvenient truths not only about the environmental catastrophes caused by our dependence on mainstream food production methods, but also by the cataclysmic social justice impact of our eating habits in the global south. The film unfolds some popular myths on topics such as plant-based diets, healthy and nutritional foods, ethical eating, food politics, industrial agriculture, and how to attain a sustainable food culture. Sustenance helps the viewer discover these themes, prompting the viewer to question where our food really comes from, and how it genuinely affects the health of other people, other species, and ultimately the entire planet.