Frances Moore Lappé’s Diet for a Small Planet (1971) became a landmark in the natural food movement by connecting personal eating habits with global hunger and environmental concerns. Its most influential contribution was introducing the concept of “protein complementarity,” teaching an emerging generation of vegetarians that they could get all essential amino acids by combining plant foods like beans and grains. By making vegetarianism both nutritionally sound and socially responsible, the book inspired millions to embrace plant-based eating as a healthy and sustainable lifestyle.