People occasionally send me questions about food. Once before, I posted my responses on this blog — that was about sustainability. This time, the questions were mostly about veganism, and I think you’ll agree that they’re worth answering. I hope I’ve done them justice.

What book about nutrition do you frequently recommend to friends?

My Year of Meats, by Ruth Ozeki. Long ago, a copy was given to me by the great Jerry Shively. It’s not actually about nutrition but it’s fun and insightful about food.  If people really want to learn about nutrition science, check out a standard textbook like Wardlaw’s Contemporary Nutrition. It’s surprisingly readable.

How much does diet really affect mood and psychological well-being?

A lot.  In my experience, mood and metabolism are closely related, but I’m no psychologist — at Tufts our expert on this is Robin Kanarek.

Is the vegan diet equally good for everyone? (Why or why not?)

No. I see no reason why everyone “should” be vegan. But many people often eat too much red and processed meat, relative to what most nutritionists consider a healthy diet.  The most recent instance of this argument is the EAT-Lancet report led by Walter Willett, who is the world champion of this view. Another reason to limit animal foods is that livestock are often treated terribly, and also cause environmental harm (eg the methane burps of cows and other ruminants, and the land used to grow feed which would otherwise be used in other ways), as well as antibiotic resistance (in settings where antibiotics for livestock are overused).   But none of those harms provide a persuasive call for zero animal foods, or even near-zero. Ultimately it’s pretty clear that the evidence favors a reducitarian or flexitarian approach, in which choices depends on local circumstances at each place and time.

In my view, zero is the right number mainly for people who want bright lines and absolute rules. Often that rigidity is a temporary — a first step towards a balanced approach.  A diet with some red meat, poultry or pork, milk and eggs can easily be helpful.  These food groups are needed for human health especially in utero and infancy for maternal and child health, and useful in agriculture for crop-livestock interactions.  Even animal welfare does not call for zero farmed animals, since that argument would rely on an ethical argument that places any suffering above the value of coming to life in the first place. 

On this and other topics, the biggest challenge I see is how to improve our own diets while helping others get more of what they want and need.  It’s not helpful to focus only on improving the diets of relatively privileged people, without doing what we can to bring better diets into reach for everyone else.  

What are the top dangers of veganism, and how would you recommend avoiding them? (More generally, things that keep people from leading a healthy, balanced, and sustainable diet.)

As far as I can tell, the main danger associated with veganism is sanctimony — real or perceived.  Whenever one groups casts itself as enlightened, others will push back and proponents risk getting stuck in an echo chamber.  Some people are very skilled at pursuing their own ideals without losing contact with others, like the brilliant journalist Ezra Klein in his memorable interview with Melanie Joy.

Three big meals or seven small meals? (A lot of people are confused about the question of snacking.)

I don’t know about meal size as such, but intermittent fasting seems like one of the most exciting new frontiers in nutrition.  Allowing for more complete digestion of everything one has eaten, especially overnight, could be a good idea for many reasons.  I’m not sure the term “fasting” is the right word, however — I’d rather just call it concentrated mealtimes, choosing times when one can plan ahead for mindful eating. 

What purchase of $50 or less has improved your ability to lead a healthy diet the most? (e.g. soymilk maker, fitness tracker, etc.)

A bathroom scale, around $20.  It’s an amazing technology, but challenging to ignore fluctuations and use it only to see trends.

If I were an entrepreneur I’d make one whose screen shows each day only as a dot relative to your moving average, and glows to say thanks when you step on it every day at about the same time. Like a wifi scale, but simpler and cheaper.

What are the two foods you’d recommend to stop eating or drastically cut out?

I wouldn’t. First because I’m not a dietitian, but also because I know they don’t shout against any one or two foods. They focus on the whole diet, because when we deliberately cut out something, we often compensate in other ways.

Ingredients are another matter — one priority for global health is to spread the ban on trans fats to developing countries like India.

What is worst advice you hear people give in the nutrition community routinely?

I’ll pass — there’s too much noise, and no need to single out anything in particular.

What’s the top “superfood” or supplement that you recommend everyone should incorporate into their diet? (Does not have to be an exotic superfood.)

There’s nothing I would recommend to everyone.  I happen to love peanut butter, but maybe that’s because it was a favorite after-school snack when I was little, and also a popular luxury among villagers in rural Zimbabwe where I lived after college. In general, I like buying things like peanuts that are often grown by poorer farmers, since those crops usually employ a lot of workers and don’t require too much energy or water.

Low-fat vs. low-carb diet for weight loss? (Is one inherently better? Does it matter?)

Definely pass — weight loss advice is for dietitians and other health professionals, not economists.

What is detoxification and how do you feel about the need for it? (Including intermittent fasting.)

Again I’m no expert on anything biochemical, but I have seen some evidence suggesting that autophagy, triggered by periods of not eating, can be helpful.  What I don’t understand is why call that detoxification — why not just call it healthy metabolism?

Breakfast or no breakfast?

Presumably that depends on the rest of one’s daily schedule and family circumstances.  I’m lucky and can choose my mealtimes, but many people don’t have that luxury.

In the past few years, what new attitude or belief has most shaped your understanding of healthy nutrition and lifestyle?

So many changes: towards lower carbs and more whole grains, towards healthier fats, concentrated meal times, exercise to avoid back pain, etc., but maybe those changes just trace my own aging!

What do you do when you’re craving junk food? (It can be when you’re traveling, at a party, etc., if you normally don’t crave it.)

I eat some and then stop.  One of the most useful ideas in all of economics is diminishing returns: the first few spoonfuls are the best-tasting, and eventually one reaches the point where harms outweigh benefits.  Economics is all about such U-shaped functions, about learning when to slow and stop. Studying the economics of food markets also helps me resist food marketing.  A lot of what we find delicious is the power of suggestion.

A little bit about you – how would you describe your work on food?

I’m an economist in a nutrition school.  That means I use nutrition science to inform my own and others’ understanding of individual behavior and societal outcomes — an example of this work is a literature review I just did called “Beyond calories: The new economics of nutrition


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