This article is an excerpt from the Shortform book guide to "How Not to Diet" by Michael Greger. Shortform has the world's best summaries and analyses of books you should be reading.
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What are the top health benefits of a plant-based diet? How can a plant-based diet help you maintain your weight?
In How Not to Diet, Michael Greger discusses why adopting a plant-based diet is the healthiest and most effective way to maintain a healthy weight. He gives two benefits of this diet that can help you be your healthiest self.
Let’s go into detail on the two health benefits of a plant-based diet.
Why a Plant-Based Diet Helps Maintain a Healthy Weight
A plant-based diet includes whole grains, legumes, fruits, and vegetables. It excludes processed foods and most animal-derived products such as meat, fish, eggs, and dairy. Because it omits foods that are calorie-dense (high in fat, sugar or salt, and starch), it’s naturally high in nutritional value and low in calories. This means that you can eat as much of these foods as you want without having to restrict portion sizes—which makes this diet both healthy and easy to stick to.
(Shortform note: While nutritionists validate Greger’s claim that a plant-based diet is low enough in calories that you don’t have to restrict portion sizes, they do warn that it could lead to nutritional deficiencies and major health problems. This is because plant-based diets lack B12 and are low in heme iron, calcium, iodine, and DHA. Therefore, before adopting this diet, plan out how you’ll fulfill your nutritional needs by adding supplements or specific ingredients. This will help you maintain your weight and keep you in good health.)
Greger explains that there are two health benefits of a plant-based diet that allow you to eat as much as you want and maintain a healthy weight:
- They reduce the number of calories your body stores as fat.
- They decrease your appetite and increase your metabolism.
Let’s explore these two positive effects in more detail.
Positive Effect #1: They Reduce the Number of Calories Your Body Stores as Fat
The first health benefit of plant-based diets that help maintain a healthy weight is that they contain plenty of fiber. According to Greger, fibrous foods reduce both the number of calories your body stores as fat and the number of calories you consume. Let’s explore these two effects in detail.
Fiber Reduces the Number of Calories Your Body Stores as Fat
According to Greger, fibrous foods reduce the number of calories your body stores as fat. This is because fibrous plants have tough outer layers that are difficult to digest. This means that your body can’t break down these foods and digest all the calories before you excrete them.
Further, fibrous foods reduce the number of calories you extract from accompanying foods: As fiber passes through your body, it mixes with and encases other foods in your digestive tract. Because this casing is indigestible, it traps the calories in these other foods and prevents them from being extracted by your body before you excrete them.
For example, people who eat whole wheat pasta (high in fiber) with a cream sauce would excrete more calories from the cream sauce than those who pair the sauce with white pasta (low in fiber). This is because the fiber in the whole wheat pasta envelops the calories in the sauce and prevents them from being digested by your body.
Fiber Reduces the Number of Calories You Consume
Greger claims that fibrous foods also reduce the number of calories you consume in the first place. This is due to two reasons:
1) They require more chewing: They take longer to eat than processed foods. According to Greger, the more you chew, taste, and keep food in your mouth, the more satiated you feel, even if the food’s low in calories. This feeling satisfies your cravings for high-calorie foods and inhibits the tendency to reach for additional helpings.
(Shortform note: Multiple studies verify that chewing more leads to eating less during a particular meal. However, while Greger focuses on how chewing food during a meal reduces the amount you eat at that meal, studies reveal that chewing something tasteless, such as flavorless gum, before meals reduces appetite and prevents compulsive eating. This is because chewing tricks your brain into believing that you’re consuming real food and satiating your appetite. Because you believe that you’re already consuming food and filling up, you pay less attention to real food—which means you don’t crave foods that lead to compulsive eating.)
2) They require more effort to digest: As we’ve discussed, food remains in your stomach until the digestive process is complete. Greger explains that, since plant-based food takes a long time to digest, it makes you feel satiated for longer. This is both because your stomach is full for a longer period of time and because, during this time, it releases a steady supply of nutrients into your bloodstream.
(Shortform note: Fiber has long been known to satiate appetite and keep us full for longer. While previous research put this down solely to Greger’s two reasons—that fibrous foods take longer to chew and digest—recent studies reveal that there’s more going on beneath the surface. Digesting fiber releases an anti-appetite molecule (acetate) into the bloodstream, which travels to and accumulates in the hypothalamus—a part of the brain that regulates hunger. Once there, it spurs chemical reactions that favor appetite suppression.)
Positive Effect #2: They Increase Your Metabolism and Decrease Your Appetite
The second health benefit of plant-based diets that help maintain a healthy weight is that, in addition to fiber and other nutritional content, fruits and vegetables are mostly full of water.
Greger explains that consuming foods with high water content fills you up more than just drinking water does. This is because water is trapped within the structure of these foods—which means your body requires more time and effort to separate the water from the food, and therefore burns more calories (The longer it takes to digest food, the more calories you burn.) As a result, eating these foods naturally increases your metabolism and helps you burn calories and fat reserves more quickly.
Further, because water-rich foods take longer to digest, they sit in your stomach for longer, making you feel full for longer. Since water has zero calories, Greger emphasizes, these foods fill you up without adding to your calorie count.
(Shortform note: In addition to increasing your metabolism and filling you up, consuming water-rich foods provides two benefits over simply drinking water: It helps you absorb more nutrients and hydrates your body more effectively. Regular water intake is essential because the body is unable to store a reservoir of water. Since your body can’t store water, any water you drink quickly passes through your digestive tract—which means it doesn’t hydrate you for long. Along the way, it also flushes nutrients out of your body before you get a chance to digest them. However, consuming water-rich foods helps your body absorb water and any accompanying nutrients more slowly—thus providing hydration and nutrition more effectively.)
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Like what you just read? Read the rest of the world's best book summary and analysis of Michael Greger's "How Not to Diet" at Shortform.
Here's what you'll find in our full How Not to Diet summary:
- How eating processed foods and animal products leads to weight gain
- Why eating plant-based foods reduces the calories your body stores as fat
- What dietary changes will help you shed excess pounds and keep them off
