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How To Reduce Cancer Risk By 80%: Q&A With Dr. David Katz

By Marc Perry / January 5, 2018

I’m thrilled to share with you an interview with Dr. David Katz who is one of the world’s foremost experts on preventative medicine and nutrition.

David Katz, MD, MPH, FACPM, FACP, is the founding director of Yale University’s Prevention Research Center. He has published nearly 200 scientific articles and textbook chapters, 1,000 newspaper articles; and authored or co-authored 15 books to date in both Nutrition and Preventive Medicine.

He has an extensive media portfolio and has received numerous awards for his contributions to public health and medical education. He is also the principal inventor of the NuVal nutritional guidance system, currently in roughly 1700 US supermarkets in more than 30 states.

You can check out Dr. Katz’ full bio at his website, which goes into more depth about his credentials, accomplishments, and books he’s written here – David Katz, MD.


1. You’ve been at the forefront of preventative medicine in the U.S. What is preventative medicine and why did you decide to dedicate your career to it?

When I did my training in internal medicine, it became very clear to me that nearly 8 out of 10 people filling hospital beds never needed to get that sick in the first place. When you recognize that so much loss and suffering is unnecessary, it’s hard to imagine not devoting yourself to doing something about it!

My interest was in leveraging what we knew about lifestyle as medicine to prevent disease, premature death, and suffering. Preventive medicine training offered the relevant skill set. Preventive medicine is the practice of both clinical and population-level strategies to identify vulnerability, and implement defenses against illness and injury, preserving health and vitality. It includes an array of clinical preventive services, such as immunization and cancer screening. In my case, though, much of the emphasis is on lifestyle as medicine, and the primary prevention of chronic disease by building good health up from its foundations.

2. In your new book Disease Proof, how did you come to the conclusion that 4 simple things – not smoking, eating well, being active, and maintaining a healthy weight – can reduce chronic disease risk by 80%?

In just the way you would expect of an academic researcher: by reading the relevant literature. This message was clear in a 1993 JAMA article entitled ‘Actual Causes of Death in the United States.’ It has been even clearer in many related studies published since. In particular, a 2009 study showed exactly this: eat well, be active, don’t smoke, and control your weight- and your lifetime risk of all chronic disease is 80% lower than those who don’t do any of these. It’s a very impressive claim, but it’s entirely evidence-based, and not at all controversial.

3. Why is smoking such an unhealthy habit?

You are taking a compound containing an array of chemicals including carcinogens, putting it in your face, and setting fire to it. How could it not be unhealthy?


4. There is a massive amount of confusion about what “eating well” means. What does eating well mean to you based on all the research you’ve done?

Wholesome foods in sensible combinations; period. Eat mostly vegetables, fruits, beans, lentils, nuts, seeds, whole grains, with or without fish, seafood, lean meats, eggs, dairy- and all of the nutrients we tend to fixate on take care of themselves. This is not a casual stand; it is the focus of much of my work: Can We Say What Diet Is Best for Health?

5. What makes a food healthy? Or unhealthy?

It depends on culture, context, and epidemiology. Getting what you need is healthy; getting what you don’t is not. If you are starving, calories make a food better; if you are obese, calories are the last thing you need, so they do the opposite. If you are not getting enough protein, protein would be healthy. If you eat too much protein, then- not so much. So, ‘nutritious’ means good for health, and what’s good for health is particular to a given population at a given time. The populations of developed countries tend to get too many calories, too much sugar, too much refined starch, too much glycemic load, too much sodium, too much unhealthy fat, etc; and too little fiber, omega-3 fat, antioxidants, etc. So- a food concentrated in what we get too little of, and free of what we get too much of- is ‘healthy.’

6. What are your top 3 tips for controlling appetite?

Eat foods close to nature; the more of your diet made up of foods with an ingredient list one word long (eg, broccoli)- the better

Control your own food choices

Keep meals and snacks simple and clean- and then eat when hungry

7. In Disease Proof, you have a chapter titled “Taste Bud Rehab”. Can you elaborate on this concept?

One of the most powerful determinants of taste preference is familiarity. If you eat lots of added sugar, salt, etc.- that is familiar, and you tend to prefer it. By trading up your choices, and dialing down your intake of such ingredients, you can acclimate to less, and less- become more sensitive to small amounts- and come to prefer foods that are more wholesome, what I call ‘loving foods that love you back.’ By trading up choices, you can avoid the unpleasantness of ‘giving up’ what you love; step-by-step, you can fall in love with better foods.


8. You’ve described how we can “reprogram our genes”. How does this happen?

DNA is not destiny. Genes have to ‘do’ something before they matter. The environment of genes influences what they do- whether they are more or less active, produce x or y. Lifestyle interventions have been shown to influence genes powerfully; cancer promoting genes can be turned off, for instance, and cancer suppressing genes turned on.

9. For millions of people, modern life is becoming more hectic, stressful, and overwhelming. How do we start feeling less overwhelmed and more in control of our health & well-being?

I don’t have a magic answer; our lives are too hectic. But if we neglect our health, it only makes things worse. We now have to handle the barrage with less vitality to call on- and have to start finding time for doctor visits into the bargain! So prioritizing health is a case of ‘pay now, or pay later.’ The ‘pay now’ option is a smaller investment, with a much greater return: more vitality, more years of life, more life in years. Being healthy actually gives you more time, and energy, to deal with the demands of modern living. But it would be nice if those demands could be dialed down a notch or two.

10. Is there anything else you would like to mention?

We tend to talk a lot about will power. In my view, we don’t talk nearly enough about skillpower. Healthy living in the modern world takes skill. Skill can be acquired. Disease Proof is the result of that conviction. It’s my job to have that skill set; and I can share it with anyone genuinely willing to acquire it. I hope many people are, because we truly could eliminate 80% of all chronic disease: heart disease, cancer, stroke, diabetes, dementia. Imagine that world! Imagine giving it to our children. The best way to predict the future is to create it. I hope we create the future our kids deserve.

Dr. Katz On TV

Here’s a promo reel of some of Dr. Katz’ media appearances. His answer to the question at 0.16 is fantastic. We’re definitely lucky to have him looking out for our best interests:


  • Brandan Searlr says:

    Absolutely SPOT ON!!
    Excellent article which says it like it is, simple, to the point, concise (just get those 4 aspects of our lives RIGHT!), and definitely very do-able.
    Thank You, Dr Katz for sharing your knowledge and WISDOM with us.

  • Hank says:

    Terrific post. The material is not only well thought out but entirely supported by numerous research studies. The table of different diets is very informative and leads to increased information on each type. This amount of accurate information is almost impossible to find. Dr Katz is a wonderful source for the keys to a healthy lifestyle.

  • manon says:

    Great article !

  • Dan says:

    Whole grains? That would be considered a processed food and also contains anti-nutrients such as gluten.

    Thoughts Marc?

    • Marc Perry, CSCS, CPT says:

      @Dan - Whole grains are not necessarily processed. I have certainly been on the fence about grains, but I don't see why wild rice, farro, Quinoa (technically a "pseudo grain") etc. can't be part of a healthy diet. It's when the grains are heavily processed into breads that have high fructose corn syrup that things start to go wrong.

      For an article Dr. Katz wrote about grains, check this out:

      Beating on Wheat and Raining on Grains: What's Really Making Us Fat and Stupid?

      For a more Grains 101 article that is research-based on BuiltLean.com, check this out:

      Are Grains Healthy, or Bad For You?

      If a guy like Dr. Katz who is a heck of a lot smarter than I am promotes eating whole grains, I would go with his findings. But at the end of the day, you need to figure out what works best for your body. If cutting out grains makes you feel great, or eating grains makes you bloated, or sluggish, then cut them out.

  • Taryn says:

    Thanks so much for sharing this info! Dr. Katz really makes it all quite easy to understand, and states things in such a way that makes us feel empowered...