They partnered with nutritionists, ran campaigns & advertisements, and repeated the message until it became common sense.
It worked. Generations of people woke up feeling guilty for skipping breakfast. Parents too drilled this habit into their children.
Nobody asked who was paying for the research.
Here is what the science actually shows. Breakfast is not inherently superior to any other meal.
Your metabolism does not shut down if you skip it. Hunger hormones, specifically ghrelin, rise and fall