The man who has been called the most influential nutritionist in the world by The Boston Globe is on a mission to get you, me and everyone to eat a mostly plant-based diet, for our personal health and the health of the planet.

He is Dr. Walter Willett, and he is one of the world's leading plant-based advocates, and he answered The Beet's questions of how we can all have an impact on this Earth Day.  Among his many titles, Dr. Willett is Professor of Epidemiology and Nutrition at Harvard T.H. Chan School of Public Health, Professor of Medicine at Harvard Medical School, former Nutrition Chairman at the Harvard School of Public Health, author of Eat, Drink and Be Healthy,  and author or co-author of over 1,700 scholarly articles. But don't let any of that get in the way of his clear and plain-spoken message. He is the warm and caring granddaddy type, who wants to read you a story about the importance of your ability to change the fate of the planet and your own personal health through the food choices you make.

For Earth Day, Dr. Willett answered The Beet's questions ranging from, "What difference does one person make?" to the outcome of our planet's climate crisis, to "How can we get people to change their diets now" for the sake of the environment and their health. My favorite line: "Almost everything important does start with one person, and everyone’s efforts will be needed to shift to the healthy and sustainable diets that we need."

A Softspoken Truth Sayer Who Has Already Changed How We Eat

Willett is the grandson of a dairy farmer, a soft-spoken scientist and a little bit of an outlier when it comes to his fellow researchers. Never one to "toe the line," he has challenged perceptions of trans fats and won over the establishment to his view (they are poison, metabolically speaking) and now he is challenging those who think that it's fringe to eat only plants and to avoid animal products.

He has made it a life's work to ever so politely speak out about inconvenient truths, as he did last fall when invited to take the podium at a health conference at Montefiore Medical Center in the Bronx. I sat on the floor in the back of a packed room, taking notes on my laptop and expected to hear another version of the same message that had been delivered by leading light after leading light of the plant-based medical world: That eating a plant-based diet helps save cardiac patients, reverse severe cardio-vascular symptoms and enlist good bacteria in the gut to fight inflammation and lower the risk of death.

Instead, Dr. Willett went rogue, talked about sustainability and specifically how our food choices now will impact whether we can feed the planet later. The world's population is growing at a rate faster than the number of burgers we can feed it and that if--my words here--we don't all FHB on the meats and change them over to veggie burgers on the grill, the entire planet is going to heat up to the point where we won't be able to sustain any healthy lifestyle, and not in the distant future, but soon. If we continue to eat the way we are, not only will we all meet an early grave from the diets that are slowly killing us, but our grandchildren's world will be unrecognizable. Okay, those weren't his exact words but that was the message I heard loud and clear; We have to change the way we eat today if we want to survive as a species for the next several hundreds of years.

I wanted to hear it again and bring it to The Beet. He kindly made time for a last-minute Q and A the day before the 50th anniversary of Earth Day. So consider this your personal version of the full Dr. Willett. Uncensored and too busy to mince words. Here is his Earth Day message, delivered patiently, as if he would tell the same bedtime story to us kids as many times as we ask him to. We just have to listen. That and change the way we eat. Now, today, and in the future. For our own sake and the sake of the planet.

The Beet: How do you want people to eat for the planet? 

Dr. Willett: "We have documented that eating for planetary health can also be eating for our personal health, so this can be a double win.  Broadly, this means shifting toward a healthy plant-based diet; I emphasize healthy because donuts and coke are also plant-based, but obviously not healthy.  A healthy and sustainable diet will be primarily fruits, vegetables, whole grains, nuts, soy, and other legumes.  While being a vegan is an option, our diet can also be good for planetary and human health if we chose to include small to modest amounts of dairy, fish, and poultry and occasionally red meat.

The Beet. What is the hardest thing to get people to change about their diet?

Dr. Willett. "Our biggest challenge is probably simply habit and inertia.  Some have suggested that a healthy, sustainable diet is more expensive, but we have seen that it can actually cost less because animal-sourced food are relatively expensive.

The Beet. Why is it so imperative now? 

Dr. Willett. Our planet is currently on a path to disaster because of climate change and other environmental impacts of our current activities.  We must make many changes quickly to avoid this, including a rapid shift to all green energy, but we can’t succeed unless we also change our diets and how we produce food.

The Beet, Are earth-friendly foods also healthy-friendly foods?

Dr. Willett. In general, earth-friendly foods are also healthy foods, but there are exceptions because grains and sugar have relatively low greenhouse gas impacts.  Thus, foods made with refined starch and sugar are cheap with modest environmental impacts but very unhealthy.  Also, much of the world’s population eats diets that are mostly starch because of poverty; these may have a relatively low environmental impact but they are nutritionally deficient in many ways.  This is clearly not acceptable.

The Beet. How do you connect the dots from Covid-19 to climate change?

Dr. Willett. The direct connections are not so clear.  However, COVID-19 has exposed the terrible state of nutrition in America; most of the factors that increase the risk of dying, including obesity, diabetes, hypertension, and heart disease, are largely due to poor quality diets that are also having a devastating effect on the environment.  We desperately need to shift to diets that are healthy and sustainable rather than the largely animal-based, overly processed foods that we are eating.

The Beet. Is it too late? And what difference can ONE person make?

Dr. Willett. Almost everything important does start with one person, and everyone’s efforts will be needed to shift to the healthy and sustainable diets that we need.  We must start with our personal diets as we won’t be taken seriously unless we do so, and then we can influence our wider circles, whether that is our family, our circle of friends, where we go to school, our worksite, the organizations we belong to, or the political world in which we live.  We are obviously coming up to a critical election, and we must do everything possible to elect leaders who commit to putting the brakes on climate change and environmental degradation more broadly.

The Beet: What is your mantra? What do you tell yourself to keep going?

Dr. Willett: I want to be able to pass on to our children and grandchildren a world that is healthy and just.  We know there is a path to achieving this, but it will require all the efforts that we can muster.

That's it for today. But here is another quote that Dr. Willett offered on a different day. Take this with you as you think about your own personal choices and your responsibility to yourself, your loved ones and your planet:

"No single food will make or break good health. But the kinds of food you choose day in and day out have a major impact." -- Dr. Walter Willett

That impact is hopefully enough to keep us all eating healthy, for our own personal wellbeing and the wellbeing of the planet. Happy Earth Day.