PDF Summary:The Master Guides: Eating to Improve Physical Wellness, by Shortform

In Western culture, you may find yourself overwhelmed by food industry ads, diet fads, and popular science articles about the latest superfoods. It can be difficult to keep up with what foods are “good” and “bad”—especially when these labels seem to change every week. Despite these mixed messages about nutrition, many experts agree that if you want to improve your physical health, eating well can be boiled down to two simple guidelines:

• Adopt a largely whole-food, plant-based diet.
• Avoid highly processed and high-sugar foods.

In this master guide, we’ll cover a range of expert advice on why eating plant-based whole foods can help prevent chronic illnesses, why processed and sugar-added foods contribute to modern health conditions like Type 2 diabetes, and why supplements don’t work the same way as the same nutrients delivered via whole foods. We’ll also touch on why you might need to account for nuanced factors, such as the source of your food and your unique body composition.

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Fung (The Obesity Code) explains that highly refined carbs are starchy sugars that have been stripped of any fiber, protein, and micronutrients that you’d find in the whole food. (Fung and Pollan both note that white flour is a prime example of this, though rice, corn, and sugar have undergone similar processes.)

These kinds of processed foods now contain much more sodium and caloric density than the primarily plant-based diet that humans ate for most of our evolution (How Not to Die). In other words, our normal biological processes haven't adapted to surviving on modern diets. In this section, we’ll dive deeper into what this means for our health and explain what these authors say about the short- and long-term health impacts of eating processed and high-sugar foods.

Short-Term Effects of Eating Processed Foods

Inchauspé explains that your mitochondria are responsible for turning glucose into energy, and this system works well when the amount of glucose your mitochondria receive matches the amount of energy your body needs. However, processed, nutrient-dense foods lead to glucose spikes: the glucose concentration in your body suddenly increases (and then dips) after you eat. When you experience a glucose spike, the mitochondria in your cells become overloaded. Mitochondria with too much glucose can’t produce energy efficiently. As a result, glucose spikes can make you feel dizzy, nauseous, and exhausted. They can also cause excess sweating, heart palpitations, stress, food cravings, and brain fog.

Fung adds that processed foods don’t satisfy your hunger because your body has no satiety signals associated with the refined carbs in foods such as white bread, snack cakes, crackers, chips, and pastries. In other words, these foods lack the protein, fat, and fiber that help you feel full.

Finally, processed foods amplify what Greger calls the dopamine reward circuit: When you eat a processed, high-sugar food like ice cream, for example, you experience a jolt of pleasure and a sugar rush. Afterward, whole foods with a normal level of sugar, such as mangoes, are nowhere near as enjoyable. Greger notes that eating whole foods resets this sensitivity.

In the next section, we’ll explain how these short-term effects of glucose spikes can lead to long-term and chronic illness.

Long-Term Impact of Eating Processed Foods

One of the long-term effects of frequent glucose spikes from eating processed foods is chronically high levels of insulin: the hormone that regulates your blood sugar (The Obesity Code). When your body can’t produce enough insulin to match the excess sugar you’re consuming, this can lead to Type 2 diabetes (In Defense of Food).

Fung adds that glucose spikes can lead to a condition called fatty liver disease. Essentially, foods with added sugars, such as table sugar and high-fructose corn syrup, cause your liver to compensate by producing more insulin. Eventually, your liver becomes insulin resistant, requiring more insulin per unit to continue taking in sugar.

Inchauspé lists many additional long-term illnesses that can result from frequent glucose spikes:

1) Overloading the mitochondria with glucose leads to the release of free radicals.

2) Elevated glucose levels and frequent glucose spikes can lead to heart disease. This is because glucose spikes contribute to cholesterol accumulation beneath the lining of our blood vessels. This eventually inhibits blood flow and sets off heart disease.

3) Glucose spikes can increase your risk of cancer in a few ways. First, free radicals increase your risk of cancer-causing DNA mutations. Second, high glucose levels lead to chronic inflammation, which encourages the rapid increase of cancer cells. Finally, high levels of insulin make cancer spread faster, increasing the likelihood that the person will die from it.

Cognitive Effects of Glucose Spikes

Inchauspé also asserts that glucose spikes can contribute to mental health struggles and cognitive decline. Research suggests that people who eat diets that lead to frequent glucose spikes experience more mood disturbances and instances of depression than people whose diets result in more stable glucose levels.

The Sum Is Greater Than the Parts: Why Supplements Don’t Work

If the nutrients and microbes in plant-based whole foods are responsible for many health benefits, can you replicate those benefits using supplements? And can you still eat processed foods while compensating for them with supplements? While the food industry promotes supplements and often fortifies processed foods with isolated nutrients like calcium or vitamins, Pollan, the Campbells, and Greger contend that this approach misses the synergistic benefits of eating whole plant foods.

Extracting specific compounds from their whole-food context ignores the myriad relationships and factors within intact foods that collectively contribute to health impacts. For example, Greger cites research showing that vitamin C supplements don’t provide the same benefits as eating whole foods with vitamin C.

Pollan echoes this sentiment, asserting that how you digest antioxidant-rich food impacts its absorption, and digesting antioxidants in a whole food appears to be most beneficial. This may be because there are several types of antioxidants within each fruit and vegetable. In one leaf of thyme, for example, there are dozens of antioxidants, and there’s no way to determine which one, if any, helps the body and whether that benefit is an isolated or compound effect. An interaction with fiber or another compound could be what activates or promotes antioxidant behaviors. By eating whole foods instead of supplements, Pollan says, you can receive the benefits even without knowing how it works physiologically.

The Campbells (The China Study) also caution against supplements, arguing they’re poorly regulated, and you don’t always know what you’re getting when you buy them. They may have unforeseen side effects and some can even cause harm. For example, many researchers caution against taking beta-carotene supplements because they’ve been shown to increase lung cancer risk, and vitamin C supplements can promote oxidative stress.

Exceptions to Avoiding Supplements

Though they generally advise whole food sources over supplements, the Campbells and Greger acknowledge that vegans and vegetarians may require a B12 supplement, as this vitamin is only found in animal products. Greger also suggests that you supplement a few other nutrients if you’re on a plant-based diet: vitamin D (due to lack of sunlight exposure in winter for those in northern latitudes), iodine, and omega-3s (via algae oil or yeast products to avoid mercury and other toxins in fish oil).

Making Decisions About What to Eat

To tie together this information about beneficial and harmful foods, Pollan provides some rules of thumb to help you make healthy food choices. They include his advice to eat green plants as well as a few other nuances to maximize physical health. Here are the key points to remember:

• Eat only real food (meaning whole foods).
• Eat more green plants, making vegetables a main dish and meat a side dish.
• Eat a variety of fruits and vegetables to consume a variety of nutrients.
• Eat wild plants and game, which are high in nutrients.
• Don’t eat food with more than five ingredients or containing high-fructose corn syrup.
• Avoid foods with health claims. Real food doesn’t typically come in packages, and when it does, it often doesn’t need a label expressing how healthy it is.
• Avoid industrialized meats and produce.

Greger applies similar principles but recommends simplifying your food choices by visualizing categories as a traffic light:

“Green foods” are unprocessed plant foods: Unprocessed means nothing bad is added, and nothing good is taken away. You can eat unlimited amounts of these foods.

“Yellow foods” are processed plant foods and unprocessed animal foods: Processed means something bad is added, or something good is taken away. For example, drinking almond milk is worse than eating almonds. Ideally, you’d replace yellow foods with their corresponding green foods, which are more nutritious.

“Red foods” are ultra-processed plant foods and processed animal foods: Ultra-processed food means that many ingredients have been added, and many good nutrients have been taken away. Eat red foods sparingly. It’s OK to eat these in small amounts if they help you eat more green foods (such as bacon bits or hot sauce with vegetables).

Caveats: Food Sources and Bio-Individuality

While Pollan, Greger, and the Campbells generally advocate eating mostly plant-based whole foods, they also mention a couple of caveats to keep in mind to ensure those foods are optimally healthy. These caveats include: considering the source of your food and considering your unique biological needs.

Consider the Source: How Soil Health and Crop Diversity Affect Nutrition

Pollan asserts that when one aspect of the food chain is disrupted, it affects the entire food chain. This means that if the soil is unhealthy, the plants grown in it will be unhealthy, as will the humans who eat the plants. This principle explains how industrialized agriculture has contributed to less nutritious produce.

After World War II, farmers began adding nitrogen, phosphorus, and potassium to soil to increase the rate of plant growth. At the same time, farms that once raised a diverse species of crops and livestock started growing mostly corn and soybeans. Both actions created plants lacking in nutrients.

When plant growth speeds up, Pollan explains, they have less time to soak up nutrients. And with fertilizer readily available, plant roots have no need to dig deep, where they would normally absorb minerals beneficial to both plants and humans. This not only makes the foods less nutritious but also makes plants more susceptible to pests and disease, which require the use of pesticides to fix. The pesticides seep into the plants and are digested as toxins in the body.

In Silent Spring, biologist and conservationist Rachel Carson details the many negative effects of pesticides on animal and human populations, including an increased risk of cancer, genetic damage, and reproductive issues as well as more acute health problems like nerve damage, vomiting, and diarrhea.

In addition to the problem of soil health, reducing the ecological diversity of farms to one or two crops means less diversity in the nutrients going back into the soil. Pollan writes that the human body requires a myriad of minerals and nutrients to function properly, and two species alone are unlikely to provide all of them, especially when those species are industrially grown.

Because of these factors, Pollan recommends eating plant-based foods from a home-grown garden or local farm with healthy soil (free of pesticides and industrial-grade fertilizer), eating diverse foods to get a wider range of nutrients, and eating wild foods, which tend to be more nutritious than domesticated crops.

Consider Bio-Individual Needs

The second caveat to the food recommendations we’ve discussed is the need to consider your unique biological needs. Everyone’s body is different, Pollan writes, and there are inherent physical differences that can either support or hinder nutritional health. For example:

• People have genetically predisposed metabolisms that break food down in different ways and at various speeds.
• Some bodies break down fats in a way that always leads to high cholesterol regardless of what they eat.
• Digestive systems vary in ecology, so they digest and process calories differently.

No human is a robot that reacts to food in the same way every time, Pollan says. Your body is constantly adjusting to your environment, and the science on the physiological makeup of the digestive system is incomplete. Based on this, we can infer that there’s no single correct way to eat all the time.

In Intuitive Eating, nutritionists and researchers Evelyn Tribole and Elyse Resch also argue that by tuning into your internal cues about when you’re hungry and full and what foods you crave, you can naturally fulfill your nutritional needs and eat foods that make you feel better.

Based on these two perspectives, it may be most beneficial to experiment with your diet to identify plant-based whole foods that support your physical health and feel good and satisfying to you. For example, if you feel like eating something sweet, you might apply the principles from these experts by opting for a sweet fruit like strawberries or a banana—plant-based whole foods that’ll also fulfill your craving.