Thought leaders in the culinary arts and public health gathered in Cambridge, Mass., for the second annual Menus of Change conference this week to discuss ways improve the health of Americans, as well as the planet.

The top three issues brought into focus were:

Climate change: Coping with the challenges climate change is presenting to the foodservice industry and conceiving of ways that restaurants and culinary educators might try to slow it down.

Protein: Finding better ways to serve, source and produce a wider and more sustainable variety of protein.

Fruits and vegetables: Figuring out how to get fruits and veggies to make up half of the average plate, including how to produce and source so much of it.

The conference’s presenters tied the three topics together, presenting evidence that excessive consumption of red meat is a leading cause of heart disease and a contributor to diabetes, and that red meat — particularly beef — is a key contributor to global warming. They said foodservice operators should try to introduce other sources of protein and also replace much of that protein with vegetables and fruit, particularly since most Americans eat more protein than they need.

Walter Willett, chair of the Harvard School of Public Health’s Department of Nutrition, fired the first salvo, saying that people who increase their consumption of red meat also increased their risk of heart disease and Type II diabetes. Conversely, he said, consumption of more poultry, fish, nuts and legumes is associated with lower risk of those conditions.

Although he didn’t say how much or how little red meat people should consume, in the past Willett has advocated for eating red meat, including beef, lamb and pork, no more than twice a week.

Next, Alan Miller, a recently retired climate change specialist with the World Bank, said that 70 percent of global agricultural land is used for livestock production, including 33 percent of total arable land that is used to raise feed crops, particularly for beef.

Kari Hamerschlag, senior program manger of the environmental organization Friends of the Earth, said that clearing land for feed crops was a major factor in deforestation, which leads to less vegetation that can remove carbon dioxide from the atmosphere. Furthermore, she said, cattle, in the process of eating and digesting grass, produce massive amounts of methane, a much more potent greenhouse gas than carbon dioxide.

Miller said that the International Energy Agency predicts that the earth’s average temperature will be as much as 3 degrees Celsius higher by the end of this century, possibly by 2050, which will result in more extreme weather conditions than humans have experienced in recorded history.

Although the cycle now in place leading to global warming “is somewhat irreversible,” Miller said, presenters advocated for a severe reduction in the consumption of red meat in general and beef in particular.