Breakfast is the most important meal of the day'—you've heard it since childhood. But what if I told you this 'medical wisdom' was actually created by a marketing department? The phrase was coined by General Foods in the 1940s to sell Grape-Nuts cereal. Not by nutritionists. Not by doctors. By advertisers. When researchers finally conducted proper scientific studies, the breakfast myth crumbled: there were no differences in weight loss, metabolism, or health markers between breakfast eaters and breakfast skippers. Yet billions in breakfast food sales and decades of medical education remain built on this marketing foundation. The breakfast myth isn't just about morning meals—it's a perfect case study in how marketing messages become medical advice.