#624: Can Athletes Eat for Performance and the Planet? – Peter Res

Can an athlete reduce the environmental impact of their diet while still meeting the demands of training, competition and recovery? Peter Res argues that these aims can be compatible, provided dietary changes are planned around the athlete’s needs.

Useful terminology and distinctions

• Sustainable diet: a dietary pattern evaluated in relation to environmental and wider societal considerations as well as nutritional adequacy. In this episode, the main focus is environmental sustainability.
• Planetary boundaries: a framework describing nine Earth-system processes relevant to a safe operating space for humanity. The Richardson et al. framework update includes climate change, biosphere integrity, land-system change, freshwater change, biogeochemical flows, ocean acidification, stratospheric ozone depletion, atmospheric aerosol loading and novel entities. Plastic pollution relates to novel entities; it is not a separate tenth boundary.
• Greenhouse gas emissions: one measure of environmental impact, commonly expressed as carbon dioxide equivalents. This cannot capture all effects on water, biodiversity, pollution or land.
• Life-cycle assessment: an accounting approach that estimates impacts across stages of a product’s life. Results depend on which stages are included, the production system, and the unit being compared.
• Plant-rich or plant-predominant diet: a pattern with a substantial contribution from plant foods that may still contain animal foods. A vegan diet excludes animal foods. The terms are not interchangeable.
• Protein-source share: the proportion of total dietary protein supplied by plants or animals. A target of 60% plant protein does not mean 60% of calories, food weight or meals.
• Protein quality: characteristics including digestibility and indispensable amino acid composition. A score for one protein source does not directly predict the outcome of a varied, adequately fed diet.
• Muscle protein synthesis (MPS): production of new muscle proteins. Short-term measurements help explain responses to feeding, but do not directly measure long-term muscle gain or sporting performance.
• Energy density: energy per unit of food weight. A high-volume diet can be difficult to consume in sufficient amounts when training expenditure is high.
• Bioavailability: the extent to which a nutrient becomes available for absorption and use. Nutrient content on a label and the amount ultimately utilised are related but distinct.

1. Prioritising environmental changes

Why beef is the principal target in the discussion

• Res identifies reducing beef and other ruminant meat as the largest dietary opportunity for many athletes. His emphasis is on both greenhouse gas emissions and land use.
• The broad evidence supports prioritising food substitution. Poore and Nemecek (2018) compiled life-cycle data across 38,700 farms and multiple environmental indicators. They documented substantial variation within foods, while showing that lower-impact animal products typically still had greater impacts than vegetable substitutes.
• The replacement matters: replacing a regular beef meal with a legume-based meal changes the