Two Nutrition Experts On Why You Should Be Eating A Variety Of Foods 

Contributing writers By Mark Bittman & David L. Katz, M.D.
Contributing writers
David L. Katz, MD, MPH, FACPM, FACP, FACLM, and Mark Bittman are co-authors of the book, How to Eat: All Your Food and Diet Questions Answered.
Couple sitting on couch and snacking on popcorn together
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Ultimately, with nutrition, we really just want to know what is true; we want to understand. We expect you do, too, and using science and sense, we attempt here to tell it like it is, and we tell you how we know how it is. And when we aren't sure, we tell you that; not everything is known.  

Both science and sense leave room for doubt and often require it. But beyond the shadow of all doubt, and resting securely on a foundation of both science and sense, is a sufficient understanding of how to eat to massively reduce your risk of chronic disease. We have, and can give you, the understanding necessary to add years to your life and life to your years, and to help save our existence on this planet. 

No, we don't know everything. But we know enough. Science, through the filter of sense, reveals more than enough reliable truth about how to eat to do a literal world of good.

Does variety matter?

That is a matter of taste. One of us eats the same breakfast pretty much every day: either a multigrain cold cereal or steel-cut oats with a mix of berries and whatever other fruit is in season, sometimes with added walnuts. The other never eats the same breakfast twice in a week and might start the day with stewed vegetables or a load of fruit, or oatmeal, or pasta e fagioli. Eat what you like.

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And this is just entirely different from variety when it comes to fruits and vegetables. 

Entirely. We should say "eat a variety of natural foods," in the sense that "natural" means "close to nature." Fruits and vegetables are members of families that total to hundreds and even thousands of nutrient compounds. While all fruits and all vegetables have some portion of them, not one of them has them all. So in the case of plants, grains, nuts, and seeds, variety is important because that's how you are going to get all the nutrients you need.

How does eating a variety of foods affect how full I feel?

Our appetite center is in the hypothalamus, and it's subject to "sensory specific satiety." It's why you might always have room for dessert: You're full for most flavor categories, but you haven't reached your threshold for sweetness. That's not necessarily a good thing, but as long as you keep the foods in the good-for-you category, it helps you enjoy eating.

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So including different flavors and spices in our diet actually makes us feel fuller?

Spice tickles the appetite center. It's long been known to neuroscientists that we fill up in a sensory-specific or a flavor-specific manner. So if you keep eating the same thing, no matter how good it is, you lose interest in it. If you switch over to food with a tasty, different flavor, you rekindle your interest anew.

What's the role of snacking in all this?

Snacking could be good or bad. When we were kids, we were told not to snack between meals because it would spoil our appetite, but "spoiling" your appetite in an age of overeating is not necessarily a bad thing. It's impossible to go wrong by eating a piece of fruit or a cucumber or carrot, no matter when you eat it.

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You're saying it's what I snack on that matters.

Snacking is there when you need it. You're peckish. Maybe your energy level is starting to slip a little bit. And then, an hour and a half or two hours after you have a snack, when it's lunch or dinnertime, you're less hungry than you would've been. Well, that all sounds good, right? As long as it's a healthy snack, it is. 

But is there any evidence that shows the benefit of snacking? Other than my own research that it puts me in a better mood when that 3 p.m. slump hits. 

We do have evidence that nutritious snacks are good for you. Remember, foragers routinely graze—they snack all the time, eating what they can when they can. While we have established breakfast, lunch, and dinner as the modern norm, it's merely convention, not biology. 

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I don't want to stress out about choosing the wrong snack or eating when I shouldn't.

You've got to be selective about your snacking, but it doesn't have to be that hard. As in other contexts, it helps to be prepared. You bring an umbrella when you think it might be rainy. In the same way, we live in a climate where unhealthy food is everywhere, so just as you would bring an umbrella to stay dry on a rainy day, bring along a healthy snack so you aren't tempted to go to the vending machine.

A good snack versus a bad snack...do I have to ask this question?

Apples, walnuts, bananas, carrots, hummus, bean dip, salad, etc., are all good. You know what we're talking about. Snack on high-quality foods all you want. On the other hand, a snack from most glow-in-the-dark vending machines is almost certainly a food that's been engineered to put your appetite center into overdrive. You will wind up feeling crummy because you will get a spike in blood sugar; you'll be extra hungry later because this is the type of food that causes fluctuations in hormone levels that actually increase total eating. Especially if you grew up eating candy bars, you're going to crave them, but you know they're not what you need.

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So it's a balance between following a healthy diet and also what works for my body and routine?

There are the fundamentals that pertain to us all: wholesome foods, healthy combinations, balance, reasonable variety, and all that. But exactly how you get there from here varies highly from individual to individual. Snacking is one of the great opportunities to personalize the format.

And do you want your passion for wellness to change the world? Become A Functional Nutrition Coach! Enroll today to join our upcoming live office hours.

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