Breast Cancer Basics: What Should I Eat Before and After Cancer

One of the most common question my patients ask me is “what should I eat” during and after my cancer treatment.

To answer this question requires knowing more about the specifics of each individual, such as:

  • What type of cancer treatments are you undergoing?
  • Do you have any difficulty or pain while chewing or swallowing?
  • Do certain foods smell or taste poorly?
  • Do your treatments (or certain foods) cause diarrhea or constipation?
  • How is your appetite?
  • Are you losing weight or need to regain weight?
  • Are you overweight, have insulin resistance or type 2 diabetes?
  • Do you have any food preferences or dietary restrictions?

Step One (Ask for Help):

Your surgeon, medical oncologist or radiation oncologist are often the first physicians you will encounter in your cancer journey, but they are not experts in nutrition and swallowing function. Nevertheless, I strongly encourage all cancer patients to ask their cancer team providers for their recommendations on the above issues. They will know which consultants to refer you to depending on the details of your situation.

If you have any of the above concerns or will likely be facing them as you go through treatment, you will need referrals:

  • Dietitian or nutritionist who has expertise in oncology (to ensure that you are getting adequate nutrition and hydration)
  • Speech language pathologist (experts who are specialized in helping patients with swallowing and speech issues)
  • Dentist or oral surgeon (to help with poor dentition, denture issues, oral hygiene)
  • Surgeon, gastroenterologist or radiologist (to place a feeding tube in the stomach or jejunum in circumstances where swallowing by mouth is either not possible due to pain or obstruction or the patient is high-risk for aspiration of foods or liquids into the lungs)
  • Functional medicine practitioner (who can test for nutrient, metabolic, hormonal and gut abnormalities and recommend targeted approaches to improve these)

Your nutritional status is absolutely crucial in supporting your body’s innate abilities to more effectively fight cancer and recover from treatments. You will be far more successful in this endeavor by having a team of experts by your side who know the details of your cancer, treatments and overall health.

Step Two (Establish Your Priorities):

When you are first diagnosed with cancer, learning about nutrition may not be your top priority. Through my years of experience, I find that many patients are in the whirlwind stage at this point and may feel in a state of information and emotion overload. If this is your situation, depending on your overall nutritional status, I recommend first focusing on getting your cancer treatment plan started. We will address the nutrition issues shortly thereafter. However, there are circumstances (i.e. significant weight loss, swallowing issues, loss of appetite, etc.) in which we need to address nutritional issues before or simultaneously with the treatment. Your cancer care team will help guide you in these priorities.

Nutrition Priority #1 (Your Weight Status)

The most important nutritional priority for me, as an oncologist, is first establishing whether each patient is overweight (excess body fat), underweight or normal weight and predicting if this is likely going to change as we go through treatment. For example, many head and neck cancer patients will develop problems with swallowing during and after treatments (i.e. chemotherapy, radiation therapy, surgery) that, if not proactively addressed, can lead to significant weight loss, malnutrition and dehydration.

My preferred measure of assessing body fat is the waist-to-height ratio (WHtR). There are other commonly used measures of fat mass, such as body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR), but recent studies have indicated that the WHtR may be the most accurate of these.

Calculate Your WHtR

Measure you height. Simply use the measurement of your height in either inches or centimeters.

Measure your waist. Use a measuring tape to get a value for your waist (either in inches or centimeters). Use the same measurement units for both waist and height.

  • Start by wrapping a tape measure around your body. Have the end (the one starting with 0) near your belly button in the front.
  • Pull the measuring tape so it’s about 1 inch above your belly button. This will accurately place the tape measure at your waist and not at hip-level.
  • Try to stand next to a mirror so you can see the tape measure around your body. Try to keep it parallel to the floor and at equal level all the way around your body.
  • Pull the tape measure so it’s snug around your waist, but not digging into your body.
  • Also, take this measurement as you breathe out, not as you’re inhaling. Your waist is naturally at its relaxed state as you exhale.

Use this calculator to enter both measurements to calculate your WHtR:

Reference: The PE Diet: Leverage your biology to achieve optimal health.

Nutrition Priority #2 (Your Daily Caloric Goal)

Once you have established if you are overweight, underweight or normal weight, the next priority is to calculate how many calories you should consume per day to reach a normal body weight. For this, I use total daily energy expenditure calculators.

The TDEE (Total Daily Energy Expenditure) is a good indicator of how many calories a person must consume in order to maintain his or her current weight. This important number is dependent on a person’s basal metabolic rate (BMR) and his or her activity level. Every day your body burns a specific number of calories just by existing. This is known as your BMR, and is based on your weight, height, and age. Since your BMR calculates the calories you need for a state of rest, you need to factor in movement and exercise to get an idea of how many calories you burn each day. To do this, you take your BMR and multiply it by an “Activity Level” factor:

  • Sedentary: 
    • You don’t intentionally exercise at all.
    • Fewer than 1,000 steps per day.
    • Activity factor = BMR x 1.2
  • Lightly Active:
    • You casually stroll through your neighborhood a few times a week.
    • On average, you walk for exercise about 30 minutes a day.
    • 15 minutes per day of vigorous exercise like running or lifting weights.
    • 1,000 to 10,000 steps or about 4 miles a day.
    • Activity factor = BMR x 1.375
  • Moderately Active:
    • On average, you walk for exercise about one hour and 45 minutes a day
    • 50 minutes of vigorous exercise a day.
    • 10,000 to 23,000 steps or 4 to 10 miles a day
    • Activity factor = BMR x 1.55
  • Very Active:
    • You work in construction during the day and you’re on the company softball team.
    • On average, you walk for exercise about four hours and 15 minutes a day
    • Two hours of vigorous exercise
    • More than 23,000 steps or 10 miles a day
    • Activity factor = BMR x 1.725

One of the biggest errors in calculating your TDEE is selecting an inaccurate activity level. Studies have shown that most people select an activity level that’s one or two categories higher than their lifestyle actually warrants.

Once you enter some basic information, the TDEE calculator will do the rest for you. I use a calculator that incorporates the above variables plus your weight goal (lose weight, maintain, gain weight/preferably muscle), calorie deficit or surplus (I recommend a 20% deficit or surplus), net carbohydrate intake per day (I recommend 50-100 net grams per day) and protein intake per day (I recommend 1.4 grams/Kg lean body mass; see below for more on protein)

An important caveats to the TDEE calculation:

  • Your TDEE estimate is just that, an estimate. Each of us have unique differences in our metabolic rate, so after a period of time (weeks-to-months), you may discover that you actually require more or fewer calories per day to meet your goal than what was estimated in the TDEE calculation.
  • As your weight changes, you will need to recalculate your TDEE (I recommend doing this after every 5 pounds of weight change) to get an updated estimate of you caloric goal.

Nutrition Priority #3 (Your Daily Protein Intake)

Protein is the most important macronutrient, as this is essential for body maintenance, growth and repair:

  • Formation and maintenance of muscles, connective tissues, red blood cells, enzymes, and hormones
  • Transporting many body compounds as well as medications
  • Maintaining the balance of body fluids
  • Fighting infections and strengthening immunity

Foods that are high in protein content have the highest concentration of nutrients (amino acids, vitamins, minerals and fatty acids), also known as nutrient density (ND). Your nutritional status depends on #1) getting enough calories per day to achieve your weight goal and #2) making sure that you are meeting all of your daily nutrient requirements (more on this later).

Another important point about high-protein content foods is that they also tend to be the most satiating (you feel fuller more quickly). Individuals who have a goal of losing weight will be more successful if they consume a diet that has a greater amount of protein calories than calories from both carbohydrates and fat (see protein leverage hypothesis or protein:energy “P:E” ratio).

Recommended Daily Protein Intake:

  • Maintain weight: If you are healthy, most adults should aim for a goal of at least 1.4 grams/Kg lean body mass.
  • Gain weight: If you have lost a significant amount of weight or are undergoing chemotherapy, radiation or surgery, the number of grams of protein needed each day may be higher. I recommend 1.8-2.0 grams/Kg lean body mass. Discuss this with your dietitian or nutritionist.
  • Lose weight: High protein diets will lead to earlier satiety, and thus a greater success in losing weight. I recommend at least 2.2 grams/Kg lean body mass. Discuss this with your dietitian or nutritionist.
Reference: The PE Diet: Leverage your biology to achieve optimal health.

Nutrition Priority #4 (Your Daily Net Carbohydrate Intake)

Did you know that carbohydrates are actually not a required macronutrient? In the absence of dietary carbohydrates, our body will make all the glucose (the main carbohydrate fuel source) it needs from protein and fat. That said, most of us consume diets that are relatively high in carbohydrates (especially refined, simple carbohydrates). There are two main carbohydrates in our diet:

  • Fiber (mostly, non-digestible)
  • Starches and sugars (mostly, absorbed and converted into glucose)

Fiber is non-essential for life, but it helps to improve intestinal motility, detoxification and gut microbiome health. Additionally, fiber-rich plant foods have a higher nutrient density and are more satiating than low-fiber foods that are high in carbohydrates. This is why diets that are higher in fiber are associated with a greater success in weight loss.

Net carbohydrates is the term that relates to the amount of dietary carbohydrates in a particular food that get absorbed and converted into glucose. To calculate net carbs, simply subtract the grams of fiber per serving from the total carbohydrate grams per serving.

To maintain lower blood sugar levels after meals, I recommend limiting net carbohydrate intake to 50-100 grams per day. For comparison, a regular Western diet can easily contain 250 grams of carbs or more in a day, most of them refined carbs, including sugar.

Why do I recommend a lower carbohydrate diet?

Due to the Warburg effect, cancer cells will preferentially use glucose as it’s primary fuel whenever it is readily available. Keeping blood glucose levels lower will reduce access to this energy source, which has been shown to slow tumor progression and improve cancer outcomes.

Warburg effect

Diets that are higher in net carbs tend to be less satiating, and often lead to excessive caloric intake and eventual weight (body fat) gain. Having too much body fat causes systemic inflammation, insulin resistance, immune suppression, impaired DNA repair and increased production of free radicals, cancer growth factors and estrogen. Each of these factors contribute to a cancer-promoting terrain in the body. Therefore, consuming foods that are more satiating (lower in net carbs and higher in protein) will lower your risk of accumulating body fat.

To better assess your body’s response to dietary carbohydrates, I recommend testing you glucose levels after meals and get a hemoglobin A1C test. If any of these levels (see below) are elevated, you may have insulin resistance and should reduce your intake of net carbohydrates.

Nutrition Priority #5 (Ensure Adequate Vitamins, Minerals, Amino Acids and Fatty Acids)

These are the essential building blocks and co-factors that your body needs to fight cancer and recover from treatments. As we accumulate nutrient deficiencies, systemic inflammation and oxidative stress (free radicals) levels increase and are associated with worse cancer and overall health outcomes:

  • Impaired immune function
  • Mitochondrial dysfunction (decreased cellular energy production, increased oxidative stress and inflammation, aging)
  • Impaired methylation (involved in gene activation/deactivation, DNA protection, detoxification, etc.)
  • Insulin resistance
  • Increased risk of cardiovascular disease events
  • Gut dysbiosis, inflammation, leaky gut
  • Mood, cognitive and memory issues
  • Endocrine imbalance (stress hormones, sex hormones, thyroid hormonal abnormalities, etc.)
  • Impaired detoxification pathways
  • Appetite stimulation & weight gain
  • Etc.
Numerous steps in which nutrients are crucial in detoxification
Mitochondrial energy production relies on nutrients
Methylation relies on nutrients

So how do you ensure that you are getting adequate nutrients from your diet?

The best way to achieve this important goal is to consume a nutrient dense diet, and my favorite tools to help you come from my colleagues, Marty Kendall (founder of Optimising Nutrition) and Saskia Lesser. We have collaborated on 3 amazing recipe books that are specifically designed for cancer patients and survivors.

We designed each of these three recipe books to take the nutritional priorities, above, into account.

When you purchase any of the three recipe books you will receive:

  • An ebook with of the most nutritious meals optimized for your goal (that you can take with you anywhere on your phone or tablet),
  • A secret index of links to the 150 most nutrient-dense recipes optimized for your goal on our website so you will never run out of nutritious ideas to try,
  • A full micronutrient breakdown showing the vitamins, minerals, essential fatty acids and amino acids that you will obtain from each recipe,
  • Access to all of the recipes pre-logged in Cronometer for your convenience, and
  • A list of the most popular nutrient-dense foods that align with your goal.

Choose This Recipe Book If You Are Overweight or Have Insulin Resistance:

Cancer: recipes for cancer patients and survivors with excess body fat and insulin resistance is for cancer patients who are currently overweight and have insulin resistance (which is identifiable on lab testing). The nutrient dense recipes will help you loose weight, reverse insulin resistance and not promote cancer growth. The last point (not promoting cancer growth) is based on the following:

  • All recipes are low in net carbs (which helps to keep your glucose levels lower)
  • All recipes are either lower in methionine or lead to a lower intake of this amino acid due to earlier satiety (Methionine is an essential amino acid that is needed by cells to repair damaged DNA and reduce oxidative stress. Depleting methionine from cancer cells targeted by DNA-damaging therapies, such as chemotherapy or radiation therapy enhances the ability of these treatments to kill the cancer cells in preclinical studies. Methionine depletion, by itself, also slows cancer growth, in preclinical studies.)
  • All recipes have lower glutamine/glutamic acid (Glutamine is the major amino acid that sustains mitochondrial energy production in the setting of low glucose levels. Numerous preclinical studies have shown that lower glutamine levels impair tumor growth.)

Choose This Recipe Book If You Want To Maintain Your Current Weight

Cancer: recipes for cancer patients and survivors optimized for weight maintenance is for cancer patients who want to maintain their current weight. The nutrient dense recipes will help you maintain weight and not promote cancer growth (the recipes are lower net carbohydrates, methionine and glutamine/glutamic acid)

Choose This Recipe Book If You Want To Gain Weight

Cancer: recipes optimized for cancer patients and survivors who are underweight is for cancer patients who want to gain weight. The nutrient dense recipes will help you gain weight and not promote cancer growth (the recipes are lower net carbohydrates, methionine and glutamine/glutamic acid)

Is there a downside to taking a multivitamin per day?

Even if you eat a nutrient dense diet, there is a much smaller chance that you will be deficient in micronutrients. However, this risk goes way up for individuals who don’t consistently follow a nutrient dense diet. For the latter, I often recommend that they take a higher quality multivitamin each day as an added insurance policy.

“According to data from the National Health and Nutrition Examination Survey (NHANES), many Americans are not meeting current intake recommendations for several micronutrients. Even when considering micronutrient intake from fortified foods and dietary supplements, an estimated 70% of the U.S. population aged 2 years and older do not meet the estimated average requirement for vitamin D, 60% for vitamin E, 45% for magnesium, 38% for calcium, 34% for vitamin A, and 25% for vitamin C. Multivitamin/mineral supplements are a simple, inexpensive, and safe way to help fill these nutritional gaps and improve micronutrient status.” -Oregon State University, Linus Pauling Institute:

“The Bottom Line: A Daily Multivitamin Is Still Good Nutrition Insurance Some scientists believe there is not enough evidence to recommend for or against taking a daily multivitamin, because there isn’t yet enough data from randomized controlled trials. That’s a reasonable but short-sighted point of view since it may never be possible to conduct randomized trials that are long enough to test the effects of multiple vitamins on risks of cancers, Alzheimer’s disease, and other degenerative conditions. Looking at all the evidence—from epidemiological studies on diet and health, to biochemical studies on the minute mechanisms of disease—the potential health benefits of taking a standard daily multivitamin appear to outweigh the potential risks for most people. -Harvard University, School of Public Health

Keep in mind: Taking vitamins with individual doses that are too high can be toxic, and taking doses that are too low will likely be ineffective. Consistently eating a nutrient dense diet avoids these issues.

Nutritional Optimisation Program

If you are looking for an approach to maximizing multiple vitamins and minerals in your diet without tracking food all the time, I highly recommend the Nutritional Optimisation Program. – which covers everything you need to know to do nutrient optimisation, step by step.

Functional medicine micronutrient assay testing

Deficiencies are typically not associated with obvious symptoms (i.e. it’s very rare to get scurvy or a massive goiter in the modern era), but inadequate levels of these nutrients still wreak havoc throughout the body. If you don’t get your levels tested, there is no way you will know if you are deficient and the degree of the deficiency.

Testing gives you a window into this important factor of your underlying health, which enables your to take corrective steps to increase your intake of specific micronutrients. Over time, repeat testing is recommended to make sure any deficiencies have been adequately corrected.

Our body requires only a small amount of these important compounds to function properly. If you overwhelm the system, you can alter the normal physiological mechanisms that use these compounds, so that instead of them be healthful, they can be harmful. This is the reason I don not recommend blindly taking micronutrient supplements (except for a quality multivitamin) unless you first get tested and identify deficiencies to correct.

I recommend these micronutrient assays to patients in my office and through my online consulting program (IOE Program).

  • NutrEval
  • SpectraCell **No longer available to order through IOE Program

We ship these kits to patients across the U.S., and schedule a follow-up call to review the results and make recommendations on how to improve deficiencies.

If you are interested in this testing, check out my lab testing information page.

Nutrition Priority #6 (Minimize Your Toxic Burden)

The above priorities, #1-5, assume that you are consuming, preparing and storing foods in ways that minimize your exposure to toxic compounds and hormone disrupters. Here are some of my more common recommendations to help you achieve this goal.

Choose foods that are:


As you have now learned, knowing what you should eat during and after your cancer treatment and through survivorship often requires a team approach. Each individual’s situation is unique, and therefore their diet has to be addressed based on their overall health, treatments and side effects. That said, the foundation of the diet is generally the same: whole food, nutrient dense, lower net carbohydrates and a focus on minimizing toxins and hormone disrupters.

While not based on clinical data, diets that are lower in methionine and glutamine may have anticancer effects.

Our three recipe books are based on the dietary foundations, above, and are great tools for patients who want to either:

  • Lose weight and improve insulin sensitivity
  • Maintain weight
  • Gain weight

Functional medicine testing for nutrient deficiencies further helps to guide on you your dietary choices. Consider getting one of these tests.

While using nutrient supplements is not preferable over consuming a nutrient dense diet, I often recommend taking a high quality multivitamin each day as a way to further ensure you are achieving the bare minimum micronutrient levels.