The Temerty Faculty of Medicine's Environmental Lecture Series: Health (human and planetary) and the Existential Threat of the Anthropocene

March 14: EAT Lancet – milk and meat


Walter Willett

Walter Willett MD, DrPH
Harvard T.H. Chan School of Public Health, US

Dr. Walter Willett is a physician and epidemiologist and Professor of Epidemiology and Nutrition at the Harvard T.H. Chan School of Public Health. He served as Chair of the Department of Nutrition at Harvard for 25 years. Much of his work has been on the development of methods, using both questionnaire and biochemical approaches, to study the effects of diet on the occurrence of major diseases. He has applied these methods starting in 1980 in the Nurses’ Health Studies I and II and the Health Professionals Follow-up Study. Together, these cohorts that include nearly 300,000 men and women with repeated dietary assessments are providing the most detailed information on the long-term health consequences of food choices. Dr. Willett has published over 2,000 research papers, primarily on lifestyle risk factors for heart disease and cancer, and has written the textbook, Nutritional Epidemiology, published by Oxford University Press. He also has four books for the general public. Dr. Willett is the most cited nutritional scientist internationally. He is a member of the National Academy of Medicine and the recipient of many national and international awards for his research.


The world is facing a health crisis due to increasing rates of obesity and diabetes, and the consequences of this pandemic will accumulate over the coming decades. Simultaneously, climate change is accelerating and is already having devastating effects that will undermine our ability to feed the world’s growing population. In turn, our food systems contribute importantly to greenhouse gas emissions, water and land use, and multiple forms of pollution. Thus, a solution to feeding what will be about 10 billion people by 2050 diets that are both healthy and environmentally sustainable presents an opportunity to mitigate many global challenges. The EAT-Lancet commission addressed this challenge stepwise by defining healthy diets quantitatively, determining whether these can be produced within planetary boundaries for greenhouse gas emissions and other environmental factors, and identifying strategies to achieve these goals. The commission found that global adoption of a flexitarian dietary pattern that could include up to about two servings per day of animal sourced foods, together with improvements in agricultural practices and reductions in food waste, would have major benefits for human health and allow us to stay within planetary boundaries. Any solution must also ensure that we rapidly shift from fossil fuels to green energy. Achieving this will require the engagement of governments at all levels, civil society, and individuals.


  1. Willett W, Rockström J, Loken B, Springmann M, Lang T, Vermeulen S, Garnett T, Tilman D, DeClerck F, Wood A, Jonell M, Clark M, Gordon LJ, Fanzo J, Hawkes C, Zurayk R, Rivera JA, De Vries W, Majele Sibanda L, Afshin A, Chaudhary A, Herrero M, Agustina R, Branca F, Lartey A, Fan S, Crona B, Fox E, Bignet V, Troell M, Lindahl T, Singh S, Cornell SE, Srinath Reddy K, Narain S, Nishtar S, Murray CJL. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet. 2019 Feb 2;393(10170):447-492. doi: 10.1016/S0140-6736(18)31788-4. Epub 2019 Jan 16.PMID: 30660336
  2. Willett WC, Ludwig DS. Milk and Health. N Engl J Med. 2020 Feb 13;382(7):644-654. doi: 10.1056/NEJMra1903547.PMID: 32053300
  3. Li Y, Schoufour J, Wang DD, Dhana K, Pan A, Liu X, Song M, Liu G, Shin HJ, Sun Q, Al-Shaar L, Wang M, Rimm EB, Hertzmark E, Stampfer MJ, Willett WC, Franco OH, Hu FB. Healthy lifestyle and life expectancy free of cancer, cardiovascular disease, and type 2 diabetes: prospective cohort study.
    BMJ. 2020 Jan 8;368:l6669. doi: 10.1136/bmj.l6669.PMID: 31915124
  4. Changes in Plant-Based Diet Quality and Total and Cause-Specific Mortality. Baden MY, Liu G, Satija A, Li Y, Sun Q, Fung TT, Rimm EB, Willett WC, Hu FB, Bhupathiraju SN. Circulation. 2019 Sep 17;140(12):979-991. doi: 10.1161/CIRCULATIONAHA.119.041014. Epub 2019 Aug 12.PMID: 31401846