Nutrition Diet: What Foods Does Dr. Li Say to Avoid?

October 26, 2025 •

4 min read

According to the World Health Organization (WHO), processed meats are a Group 1 carcinogen, a category echoed by Dr. William Li's advice on what foods does Dr. Li say to avoid to support the body's natural defenses. His approach, detailed in Eat to Beat Disease, focuses on amplifying health through nutrient-dense foods, rather than a restrictive mindset.

Quick Summary

Dr. William Li recommends minimizing ultra-processed foods, refined sugars, and processed meats to protect the body's defense systems and overall health. He advocates for whole, nutrient-rich foods that activate the body's natural healing abilities.

Key Points

Minimize Ultra-Processed Foods: Dr. Li advises against products like sodas, fast food, and many packaged snacks containing high levels of fat, sugar, and artificial additives.
Avoid Processed and Cured Meats: Processed meats like bacon and hot dogs are classified as carcinogens by the WHO and linked to heart disease and cognitive decline.
Reduce Added and Refined Sugars: Limit added sugars from sources like soft drinks and pastries, which cause blood sugar spikes and can impair stem cell function.
Limit Saturated and Trans Fats: Minimize intake of unhealthy fats found in butter and fried foods, replacing them with beneficial plant-based oils.
Read Ingredient Labels Carefully: Always check for long lists of additives, preservatives, and unfamiliar ingredients, as a sign of heavy processing.
Prioritize Whole, Natural Foods: Shift focus from a restrictive mindset to one that emphasizes consuming nutrient-dense, whole foods to support the body’s defenses.

The Core of Dr. Li's Dietary Philosophy

Dr. William Li, a renowned physician and scientist, emphasizes a "Food as Medicine" approach to nutrition. Rather than concentrating solely on what to eliminate, his strategy involves eating specific foods that activate the body's five health defense systems: angiogenesis, regeneration, the microbiome, DNA protection, and immunity. By focusing on adding protective foods to your diet, you naturally reduce your reliance on those that harm your body's defenses. This proactive strategy is at the heart of his best-selling book, Eat to Beat Disease.

Key Food Categories to Minimize or Avoid

While Dr. Li prefers an additive approach, he is clear about which foods and food types to actively limit or remove from your diet to prevent damage to your body's defense systems. The primary culprits are those that have been heavily processed, stripped of fiber, and loaded with unhealthy additives.

Ultra-Processed Products

These are items that bear little resemblance to their original ingredients and have been chemically altered with multiple additives to extend shelf life and enhance palatability. Dr. Li explains that the body does not recognize these "chemical foods" in the same way it does real, whole foods. The damaging impact comes from artificial sweeteners, artificial colors, preservatives, and added sugars that can wreak havoc on your metabolism and digestive system.

Examples of ultra-processed products to limit:
- Sodas and sugary drinks
- Packaged snacks like chips, cookies, and candy
- Frozen dinners and pre-packaged meals
- Sugary breakfast cereals
- Low-fat yogurts with added emulsifiers

Processed and Cured Meats

Dr. Li, and the World Health Organization, classify processed meat as a Group 1 carcinogen. These meats, such as bacon, hot dogs, and some deli meats, are often high in saturated fat and sodium, and may contain preservatives like nitrates. Overconsumption of processed meats has been linked to an increased risk of heart disease, certain cancers (especially colorectal), and even cognitive decline.

Added and Refined Sugars

Dr. Li distinguishes between naturally occurring sugars in fruits (which are paired with beneficial fiber) and added or refined sugars, which are not. Added sugars, such as high-fructose corn syrup, can cause rapid blood sugar spikes, which have been shown to damage the body's regenerative stem cells. This impairs the body's ability to repair itself and can contribute to chronic diseases like diabetes and heart disease. He also advises avoiding artificial sweeteners due to potential negative effects on gut bacteria and metabolism.

Unhealthy Fats like Butter

While some fats are essential for health, Dr. Li recommends limiting fats that are high in saturated and trans fats, such as butter and fried foods. Studies have shown that replacing saturated fats with healthier plant-based oils can reduce the risk of heart disease. Instead, he promotes healthy fats from sources like extra virgin olive oil, nuts, seeds, and avocados. He also advises limiting fried foods, as frying can introduce trans fats and other harmful chemicals.

Comparison: Foods to Limit vs. Better Choices


Food to Limit/Avoid	Reasons for Avoiding	Healthier Alternative
Processed Meats (bacon, hot dogs, sausage)	High saturated fat, high sodium, linked to cancer (WHO Group 1 carcinogen).	Lean Proteins (grilled chicken breast, fish) or Plant-based Proteins (lentils, beans, tofu).
Ultra-Processed Snacks (chips, packaged cookies)	High fat, salt, and sugar; artificial additives, lack of nutrients.	Whole Food Snacks (nuts, seeds, fresh fruit) or Homemade Snacks.
Added Sugars (sodas, candy, some pastries)	Rapid blood sugar spikes, impairs stem cell function, risk of chronic disease.	Water, Herbal Tea, or naturally sweet Fruit (fiber included).
Butter	High in saturated fat, promotes inflammation, linked to increased health risks.	Plant-based Oils (extra virgin olive oil, avocado oil) for cooking and flavor.
Refined Grains (white bread, white rice)	Stripped of fiber and nutrients; can cause blood sugar spikes.	Whole Grains (oats, sourdough bread, brown rice), Legumes.

Making the Right Food Choices

Making informed food choices is paramount to supporting your body's defenses. Dr. Li's approach is not about deprivation but about mindful, science-based decisions. He encourages reading ingredient labels and favoring foods that are as close to their natural form as possible. Instead of grabbing a sugary soda, opt for water. Instead of processed deli meat, choose lean protein or a plant-based alternative. Small, consistent swaps can have a significant cumulative impact on your health.

The Role of Minimally Processed Foods

It is important to differentiate between harmful ultra-processed foods and minimally processed foods, which can be part of a healthy diet. For example, edamame is a whole food, while tofu is a minimally processed form of soy with its beneficial properties intact. Likewise, canned or frozen fruits and vegetables can offer similar nutrients to fresh ones, provided they don't contain excessive additives. The key is to check the label for long lists of unfamiliar ingredients.

Conclusion: The Bigger Picture of Food as Medicine

Dr. William Li's advice on what to avoid is simply one side of a broader nutritional strategy. His core message is that by limiting foods that weaken our defenses—primarily ultra-processed items, excess added sugars, processed meats, and unhealthy fats—we create space to nourish our bodies with foods that activate and strengthen them. The result is a diet that not only helps prevent disease but also empowers our body's innate healing abilities. It’s a shift from a defensive diet to a diet of empowerment, using food as the most powerful form of medicine. For a deeper dive into the science, refer to his work.

Additional Resources

Dr. William Li: The Official Website for more information on the "Eat to Beat Disease" philosophy.
The International Agency for Research on Cancer (IARC) provides the WHO classification of processed meat as carcinogenic.

Frequently Asked Questions

Dr. Li highlights that processed meats, such as bacon and hot dogs, are high in saturated fats and sodium. He cites the World Health Organization's classification of these meats as Group 1 carcinogens, linking them to increased health risks, including certain cancers.

No, Dr. Li differentiates between naturally occurring sugars in fruits and added, refined sugars. He emphasizes that refined sugars, which lack fiber, cause blood sugar spikes and can harm stem cells, while natural sugars from whole foods are not the enemy.

Ultra-processed foods are artificially manufactured with numerous additives, unhealthy fats, and sugars. Dr. Li explains that the body doesn't recognize these chemical compounds, leading to disrupted metabolism, inflammation, and compromised health defenses.

Dr. Li advises limiting butter and other high saturated fat sources, recommending moderate and infrequent use. He suggests opting for healthier, plant-based fats like extra virgin olive oil, nuts, and seeds instead, which have been linked to better health outcomes.

Yes, Dr. Li distinguishes between harmful ultra-processed foods and minimally processed foods. Items like tofu, frozen vegetables, or canned goods with minimal added ingredients are often acceptable and can be part of a healthy diet.

A key indicator is a long ingredient list featuring artificial colors, flavors, preservatives, sweeteners, and items rarely used in home cooking, such as high fructose corn syrup and hydrogenated oils. Choosing foods as close to their natural state as possible is the best approach.

Yes, Dr. Li generally recommends avoiding artificial sweeteners. He notes that these can have negative consequences for the gut microbiome, weaken blood sugar metabolism, and may contribute to weight gain.