Dr. Ian Smith Breaks Down His 30-Day Clean & Lean Diet

You may know Dr. Ian Smith as our resident doctor, but he's also a super lean fitness machine!

The New York Times bestselling author's 17th (!!) book is called Clean and Lean: 30 Days, 30 Foods, a New You! (which also has an accompanying app called Dr. Ian's World) — and he stopped by our show to explain exactly what that means.

"Clean & Lean is clean eating meets intermittent fasting," Dr. Ian says.

He explains that with intermittent fasting, you break up your day between "feeding times" and "fasting times" — and when you're feeding, you want to eat cleaner foods.

When you're fasting, you can have water, tea and coffee, but the key is this, according to the doc: "When you're fasting, your body drives into your fat stores for the energy," he says.

"And studies have shown that intermittent fasting will reduce your inflammation," and stimulate weight loss, he claims.

Intermittent fasting along with clean eating is the formula behind the doc's 30-day program.

Flexibility is also important, Dr. Ian says. "You choose what your fasting time is."

RELATED: Does Eating "Clean" Mean You Have to Give Up Cheese and Bread? Dr. Ian Smith Answers!

You begin with a list of 30 clean foods for 30 days. And it's not all fruits and veggies, either! In addition to eating your favorite types of produce, you can also have whole grains, cheese and other dairy, olive oil and plenty of spices to keep your meals flavorful.

Then, you decide how you want to break your day up, in a way that works for you.

You can do a 16/8 — 16 hours of feeding, 8 hours of fasting — or you can do a 14/10, or a 12/12.

So, what kinds of clean foods can you eat on Dr. Ian's Clean & Lean diet?

Before we dive into that, there are a few key words to know:

Essential minerals: "When you see the words essential mineral, it means that this is something you must get from your diet — that your body does not produce it," the doc explains.

Macronutrients: "When you see something that says macronutrient, that means you need it in macro amounts — large amounts," he continues.

Trace: "When you see 'trace,' that means you need it in small amounts," Dr. Ian says.

Dr. Ian shows us how to "SCIM" the grocery store, with an easy-to-remember acronym that stands for Selenium, Copper, Iodine, Magnesium — four minerals that he says are very important for us to have. Plus, he highlights specific foods that supply each of these minerals.

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SELENIUM

Selenium helps us produce energy, Dr. Ian says. And although we only need it in trace (AKA small) amounts, selenium is very important.

FOOD TO LOOK FOR: Brazil nuts are one of the best sources of selenium, according to the doc, so add those to your basket!

COPPER

Copper is found in all of the body's tissues, according to Dr. Ian. It plays a role in making red blood cells and maintaining nerve cells and the immune system, so it's necessary for survival.

FOOD TO LOOK FOR: We can get copper from leafy green vegetables like spinach and kale, as well as from shiitake mushrooms, Dr. Ian says — so make sure to grab those from the produce aisle, too!

IODINE

"You need iodine for your thyroid hormone," Dr. Ian says.

FOOD TO LOOK FOR: Seaweed, corn and green peas all contain iodine.

MAGNESIUM

"Magnesium is important for your nerve conduction, for your heart, for reducing your anxiety," the doc says.

FOOD TO LOOK FOR: Good sources of magnesium include avocados, bananas, berries and yogurt.

RELATED: Real Housewives Star Cynthia Bailey Tried Dr. Ian's Clean & Lean Diet For 30 Days — Here's How It Went