368 ‒ The protein debate: optimal intake, limitations of the RDA, & whether high-protein is harmful

The ubiquitous RDA for protein is 0.8 grams per kilogram of body weight. This recommendation emerged from early studies focused on achieving nitrogen balance, which was considered sufficient for survival. It was not intended to represent an optimal or upper limit for protein intake.

Early studies, such as the 1928 potato-only diet trial and later USDA studies, primarily involved young, lean, inactive, sedentary individuals. These populations maintained nitrogen balance at 0.8g/kg, but the findings may not apply to active individuals, older adults, pregnant women, or those with specific health/performance goals.

Current evidence does not show compelling or intrinsically meaningful evidence of harm from higher protein intake in humans, including increased cancer or heart disease risk. Mouse studies and observational epidemiology, often cited as concerns, have significant limitations and may not generalize to human health outcomes.

For individuals aiming to thrive, build muscle, slow aging, or enhance physical performance (beyond mere survival), a protein intake in the range of 1.6 to 2.0 grams per kilogram of body weight per day is generally recommended. This should ideally be spaced out throughout the day.

Pharmaceuticals are patentable, allowing companies to recoup massive R&D investments, as mandated by the FDA for drug approval. In contrast, food products are often not patentable, and the food industry has much lower profit margins. Government funding (NIH) also often prioritizes 'deep scientific hypotheses' over practical nutritional questions, and there can be misprioritization of funding towards less informative observational studies.

Nutrition epidemiology faces issues like confounding (especially by culture, socioeconomic status), non-random measurement error in self-reported food intake, and selection bias. There's also a lack of sincerity in reporting from investigators and an inability of journal editors to fully scrutinize raw data, leading to potentially manipulated information.

There's no single universally accepted definition, though the NOVA system is common. The distinction relates to the number and type of processing steps/ingredients. The categorization is controversial because it treats very different foods (e.g., meal replacement shakes, chocolate bars, TPN nutrition) similarly, and the concept itself is seen as a 'social construct' used to demonize certain foods.

While it can serve as a simple heuristic or 'rule of thumb' for individuals to reduce calorie-dense foods, it's considered a suboptimal tool. Its effectiveness is limited by clever marketing that skirts definitions and by the fact that the actual chemical composition, not the processing level, determines a food's effect on the body. It often doesn't lead to long-term behavioral change.

Obesity is intrinsically difficult to manipulate due to its link to survival, preference for variety, and the desire for freedom of choice. Interventions like school programs, farmers markets, or calorie labeling haven't shown large, meaningful effects and often result in 'whack-a-mole' effects where individuals compensate elsewhere. There has been a 'failure of courage, honesty, and creativity' to propose radically different solutions.

David Allison suggests two main approaches: making bariatric surgery freely available for a subset of the population to reduce immediate suffering, and investing in research on the long-term effects of general education, parental support, and financial security on obesity levels, rather than just nutrition education. He also raises the possibility of GLP-1 agonists becoming a default preventative measure.