What defines processed versus ultra-processed foods?

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David Allison is a world-renowned scientist and award-winning scientific writer who has spent more than two decades at the forefront of obesity research. In this episode, David joins for his third appearance on The Drive to bring clarity to one of the most contentious topics in modern nutrition—protein. He explores the historical pattern of demonizing macronutrients, the origins and limitations of the RDA for protein, and what the evidence really says about higher protein intake, muscle protein synthesis, and whether concerns about harm are supported by actual data. He also discusses the challenges of conducting rigorous nutrition studies, including the limits of epidemiology and crossover designs, as well as conflicts of interest in nutrition science and why transparency around data, methods, and logic matter more than funding sources. The episode closes with a discussion on processed and ultra-processed foods, the public health challenges of tackling obesity, and whether future solutions may depend more on drugs like GLP-1 agonists or broader societal changes. This is part one of a two-part deep dive on protein, setting the stage for next week’s conversation with Rhonda Patrick.

We discuss:

• The cyclical pattern of demonizing different macronutrients in nutrition and why protein has recently become the latest target of controversy [3:15];
• The origin and limits of the protein RDA: from survival thresholds to modern optimization [6:30];
• Trust vs. trustworthiness: why data, methods, and logic matter more than motives in science [13:30];
• The challenges of nutrition science: methodological limits, emotional bias, and the path to honest progress [17:15];
• Why the protein RDA is largely inadequate for most people, and the lack of human evidence that high protein intake is harmful [30:30];
• Understanding the dose-response curve for muscle protein synthesis as protein intake increases [45:15];
• Why nutrition trials are chronically underpowered due to weak economic incentives, and how this skews evidence quality and perceptions of conflict [48:15];
• The limitations and biases of nutrition epidemiology, and the potential role of AI-assisted review to improve it [56:15];
• The lack of compelling evidence of harm with higher protein intake, and why we should shift away from assuming danger [1:04:15];
• Pragmatic targets for protein intake [1:09:30];
• Defining processed and ultra-processed foods and whether they are inherently harmful [1:16:15];
• The search for a guiding principle of what’s healthy to eat: simple heuristics vs. judging foods by their molecular composition [1:25:00];
• Why conventional public health interventions for obesity have largely failed [1:38:15];
• Two ideas from David for addressing the metabolic health problem in society [1:42:30];
• The potential of GLP-1 agonists to play a large role in public health [1:46:30]; and
• More.

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