Interviewer: [paraphrased] "You speak of calorie dense foods; so you're singing, 'keep foods like almond butter and peanut butter to a minimum', right?"

Dr Greger: "Yes, because of the Wall Off Your Calories rule. I mean if there is one piece of advice that really wraps up my entire book, it would be: Wall Off Your Calories!

Animals cells are encased in easily digestible membranes which allow the enzymes in our gut to effortlessly liberate the calories within a steak, for example. But plant cells are encapsulated by cell walls which are made out of fiber — which act as indigestible physical barriers, so many of the calories remain trapped. Processed plant foods, however, fruit juice, sugar, refined grains — even whole grains if they have been powdered into flour — have had their cellular structure destroyed, their cell walls cracked open and their calories are free for the taking!

But when we eat structurally intact foods — chew all you want — you still are gonna end up with calories completely encapsulated by fiber which then bunts the glycemic impact, activates the ileal break which dials down your appetite, and provides sustenance to your friendly flora. That's where we got to get all our proteins, carbs, fat from. We need to get all our macronutrients (sources of calories) encased in cell walls. In other words, from whole intact plant foods. Nut butters and seed butters are like the 'flours of the nut kingdom' because they have had their cellular structures destroyed. So, fine… eat nuts, eat seeds, just not nut butters and seed butters… I'm not saying they are not healthy but for weight loss, we want our calories encased in cell walls."

Dr Greger: "Animal cells are encased only in easily digestible membranes which allow the enzymes in our guts to effortlessly liberate the calories within a steak, for example. On the other hand, plant cells have cell walls that are made out of fiber which acts as an indigestible physical barrier so many of the calories remain trapped.

Processed plant foods — fruit juice, sugar, refined grains, even whole grains if they have been powdered into flour, have had their cellular structure destroyed — their cell walls cracked open and their calories are free for the taking. But if you eat structurally intact plant foods — chew all you want — you're still gonna end up with calories completely encapsulated by fiber which then blunts the glycemic impact, delivers sustenance to your friendly flora, activates what's called the ileal break which dials down appetite, and frankly, dumps trapped calories out the other end!

So, bottomline: try to make sure as many of your calories as possible — your proteins, your carbs, your fats — are encased in cell walls, in other words, in whole intact plant foods. That's what nature intended to happen! Millions of years before we learnt how to sharpen spears, mill grains and boil sugarcane, our entire physiology is presumed to have evolved in the context of eating what our great ape cousins eat: plants!

Juicing & Blending:

"All plants are composed of cells whose walls consist mainly of cellulose, a type of carbohydrate. Humans do not have the enzyme capable of breaking down cellulose, so we cannot utilize cellulose as an energy source. The only way we can break down these walls and release the most nutrients possible from the cells into the blood is by thoroughly chewing fruits and vegetables."

"However, when we chew a salad, we often don't do an efficient job of crushing every cell; about 70-90 percent of the cells are not broken open. As a result, most of the valuable nutrients contained within those cells never enter our bloodstream and are lost. They just travel through our bodies until they are excreted. This is one of reasons why practicing the chewing exercises detailed in Phase One is so important to the Eat for Health plan."

"An even more efficient way to ensure you receive these needed nutrients is using a blender to puree raw, leafy greens. The blending process aids your body in the work of breaking down and assimilating nutrients. It guarantees that a higher percentage of nutrients will be absorbed into your bloodstream."

"Making "green smoothies" or "blended salads" is also a delicious and convenient way to pump up your consumption of greens. It is amazing how many people love the taste of these liquefied mixtures of raw greens and fruit that can be made in a high-powered blender. While you sip or eat a creamy smooth blended salad with a spoon, think about all of the nutrients that are now powering your body to restore and maintain optimal health. Savory blended salads can be made with endless combinations of vegetables & fruits."