What Should I Eat? An Honest Guide to Diet and Breast Cancer

Dr Vidhu Shekhar Khare · Breast Surgical Oncologist, Apollo Athenaa, New Delhi

Almost every patient asks me some version of this question, usually in the last two minutes of a consultation, often slightly apologetically: “Doctor, what foods should I avoid?” — “डॉक्टर, खाने में क्या परहेज़ करना है?”

It is a fair question, and it deserves a better answer than the one most people get — which is either a vague “eat healthy” or a rigid list handed down by a relative, a WhatsApp forward, or a wellness account selling something.

Here is what I actually tell my patients, and what the evidence behind it does and doesn’t say.

Start here: four things (not forty)

For someone who has had breast cancer, the guidance that has genuine evidence behind it is short enough to fit on a prescription slip:

Eat a varied diet high in fibre and low in saturated fat.
Be physically active.
Keep to a healthy weight.
Keep alcohol as low as possible — ideally none.

That’s it. That is the evidence-backed core, and it lines up with the American Cancer Society’s Nutrition and Physical Activity Guideline for Cancer Survivors (2022) and the NCCN Survivorship Guidelines (v2.2025).

Everything beyond those four — the single foods, the miracle juices, the elaborate protocols — sits in a much greyer zone. Not because doctors are hiding something, but because the research genuinely hasn’t settled it yet. I would rather tell you that honestly than pretend to a certainty I don’t have.

What a balanced plate looks like — in an Indian kitchen

The good news is that you probably don’t need a new cuisine. A traditional thali — a grain, a dal or other protein, two vegetables, curd, a little pickle — is already close to a balanced plate. So is a Mediterranean-style pattern. There is more than one good way to eat.

Aim for something from each group daily:

Fruit and vegetables — at least five portions of a variety a day. Fresh, frozen, tinned or dried all count. Seasonal local produce is usually both cheapest and best.
Starchy foods — rice, roti, potato, millets like bajra, jowar and ragi. Choose whole grain where you can: brown rice, whole wheat atta, oats.
Protein — dals, rajma, chana, lobia, paneer, tofu, soya, curd, nuts and seeds cover this comfortably on a vegetarian diet. If you eat eggs, fish or meat, they count too. Fish about twice a week; keep red and processed meat low.
Milk and alternatives — milk, curd, paneer, buttermilk, or fortified soya and nut milks. Lower-fat, lower-sugar options where possible.
Oils and fats — unsaturated oils such as mustard, groundnut, rice bran, sunflower or olive, used sparingly. Ghee, butter, coconut oil and vanaspati for occasional use.
Fluids — six to eight glasses a day, roughly 1.5 to 2 litres.

A few practical things that help more than people expect: cook vegetables and dal into the same dish so a balanced meal doesn’t take extra work; taste before adding salt, because pickles, papad and packaged masalas add up fast; and remember that some of the worst sugar offenders look virtuous — packaged fruit juice, flavoured curd, breakfast cereals, health drinks, and a great many products labelled “diet” or “sugar-free”. Read the label, not the front of the pack.

And please — eating well does not mean giving up the foods you love. If most of your week follows a sensible pattern, there is room for a sweet after dinner or a festival meal without guilt.

Eating during treatment: the practical half

This is where most of the real difficulty lives, and where general dietary advice stops being useful.

After surgery. Most people are eating on the day of surgery or shortly after. Protein matters particularly while a wound is healing — dal, eggs, curd, paneer, fish, chicken, nuts. If your appetite is small, eat little and often rather than waiting for a big meal to appeal.

When appetite drops. Five or six small meals beat three large ones. If solid food doesn’t appeal, drink your nutrition: milkshakes, smoothies, lassi, fresh juice, soup, dal water, khichdi. A short walk before a meal can wake up your appetite. Don’t fill up on fluid immediately before eating.

When appetite increases. Steroids given alongside chemotherapy make many people much hungrier. Fill up on fruit, vegetables, salads and dals; watch the sugar in packaged foods; swap sugary drinks for water, chaas or unsweetened nimbu pani.

Nausea. Small frequent sips rather than a large glass. Many people find cold or room-temperature food easier, because hot food carries a stronger smell. Plain foods — curd rice, khichdi, toast, idli, banana — are usually kindest on a bad day. And tell your team if the first anti-sickness medicine isn’t working well enough; there are several to choose from.

Taste changes. Food may taste bland, odd, or different week to week. Some drugs leave a metallic taste — eating with wooden or good-quality plastic spoons instead of steel helps, as does cooking in glass or ceramic rather than metal. Keep trying a variety of foods; what you go off this cycle you may enjoy the next.

A sore or dry mouth. Soft or liquid foods — dal, soups, curd rice, khichdi, upma, smoothies, custard, kheer. Ice chips or an ice lolly soothe. Avoid crunchy, very salty, very spicy, sharply sour or piping hot food, and skip citrus juices while the mouth is sore. Smoking and alcohol both make it worse.

Loose motions. Fluids matter most — water with a little salt and sugar, coconut water, thin buttermilk, or an ORS. Plain rice, curd, banana and boiled potato are gentle while it settles. Call your team if you have four or more episodes in 24 hours, or if you cannot keep fluids down.

Constipation. Fibre, fluids and gentle movement, in that order of neglect. Whole grains, dals and beans, vegetables, fruit (papaya, guava, orange, prunes, figs), and isabgol if your team agrees.

On infection risk: chemotherapy can lower your white cell count, and your team may give you specific food advice if yours is low. Note that current ASCO guidance does not support blanket “neutropenic diets” that exclude raw fruit and vegetables. What genuinely helps is careful food hygiene — wash hands and produce, keep raw and cooked food apart, cook thoroughly, refrigerate leftovers promptly and reheat them fully. Follow what your own team tells you, since it is based on your counts.

The questions I get asked most

Soya. This is the single most common worry, and the answer is reassuring. Soya foods contain phytoestrogens, which are structurally similar to oestrogen but act far more weakly on the body. They are not the same as female hormones. Current evidence suggests a diet containing naturally occurring phytoestrogens is safe after breast cancer, and limited data even suggest soya food intake after diagnosis may be associated with lower recurrence risk. Two caveats: concentrated soya supplements are a different matter and are not recommended, and neither are herbal phytoestrogen preparations such as black cohosh, red clover or sage.

Sugar. There is no evidence that cutting out sugar reduces recurrence risk. You do not need a sugar-free diet. The reason to go easy on mithai, biscuits and fizzy drinks is weight gain — which does matter — not because sugar “feeds” cancer.

Dairy. No evidence that dairy increases the risk of cancer coming back. Milk, curd, paneer and cheese are useful sources of protein, calcium and vitamins. Just choose lower-fat versions where the fat adds up.

Organic food. No link has been found between an organic diet and recurrence risk, before or after diagnosis. Washing fruit and vegetables well matters more — and costs nothing.

“Superfoods.” Superfood is a marketing term, not a scientific one. Turmeric, green tea, blueberries, broccoli, wheatgrass, noni and soursop juice are all sold this way. Many are perfectly good things to eat. But no single food reduces the risk of breast cancer developing or coming back. It is the claim, not the food, that’s the problem.

Special “cancer diets” — macrobiotic, alkaline, grape-based, extended juice fasts, high-dose supplement plans. There is no conclusive evidence that any of these reduce recurrence risk. They tend to be restrictive and expensive, and they can leave you short of nutrients — sometimes causing anaemia or thinning of the bones at exactly the point your body needs the opposite.

Fasting around chemotherapy. Some early studies suggest short-term fasting may reduce side effects. The evidence is not strong enough to recommend it. If you are considering fasting for religious reasons or any other, tell me first so we can plan it safely around your cycles — that conversation is always welcome.

Supplements. If you’re struggling to get nutrients from food, I may prescribe something. Otherwise you probably don’t need one. The evidence on safety and effectiveness is mixed for most vitamins, herbal remedies, ayurvedic preparations and probiotics; they aren’t tested or regulated as rigorously as medicines, so what’s in the bottle isn’t always what’s on the label, and some can interfere with how chemotherapy, radiotherapy and hormone therapy work. Talk to your team before starting anything — and bring the pack, because the ingredient list is what we need to see.

Weight, bones and hormone therapy

Weight often creeps up on hormone therapy — because fatigue or joint pain keeps you less active, because appetite has changed, or because treatment has brought on menopause. This is not a failure of willpower. It is worth addressing, because keeping to a healthy weight is one of the few diet-related things that clearly supports long-term health.

If you need to lose weight, aim for a steady 0.5 to 1 kg a week through small sustainable changes, not a strict diet. Keep tempting snacks out of the house and easier ones within reach — roasted chana, murmura, makhana, fruit, a handful of nuts. Use a smaller plate. Don’t skip meals or try extreme diets; they backfire and leave you short of nutrients. Ask a friend or family member to do it with you.

On activity: aim for at least 150 minutes of moderate activity a week, building towards 300 if you can, plus strength work twice weekly. Break it up however suits you — six 25-minute walks is a perfectly good week. ASCO’s 2022 guideline found that exercise during treatment reliably improves fatigue, fitness, strength, mood and quality of life, which makes it the most evidence-backed lifestyle intervention we have.

If you have lost weight, the direction reverses: roughly 300 to 500 extra calories a day, more protein, healthy fats, and drinkable calories on hard days — lassi, badam milk, sattu, milkshakes with added milk powder.

Bones. Chemotherapy and hormone therapy can both thin the bones, so calcium and vitamin D deserve attention. Good calcium sources include milk, curd, paneer and cheese; ragi, which is one of the richest plant sources; til and almonds; methi, sarson, amaranth, cholai and drumstick leaves; pulses and calcium-set tofu; small fish eaten with bones; dried apricots and figs. Vitamin D comes mostly from sunlight — 15 to 20 minutes on arms and face most days — with oily fish, egg yolks and fortified foods contributing. Deficiency is common in India, so ask me to test your level rather than guessing.

Cholesterol. Aromatase inhibitors such as anastrozole and letrozole can raise LDL. Less saturated fat, more fibre, staying active and keeping to a healthy weight all help. A lipid test tells us whether anything needs changing.

If you are living with metastatic breast cancer

There is no scientific evidence that a special diet changes the outlook in metastatic breast cancer, and no diet you should have followed. Nothing you ate caused this.

What a good diet does do is give you energy, help you tolerate treatment, and lift your mood. What that looks like depends entirely on you — your treatment, your symptoms, and what you actually feel like eating. Enjoyment counts. If a food gives you pleasure on a hard day, that is reason enough to eat it.

What to bring to your next appointment

You are welcome to bring this list and write on it:

Is my current weight healthy for me, and should I be aiming to change it?
Are there foods I should avoid on this particular treatment?
Am I getting enough protein and calcium — and how would I know?
What can I eat on the days when nothing appeals?
Do I need a vitamin D or calcium supplement, and should I be tested first?
I already follow a diet for diabetes, kidney disease or another condition. Does anything need to change?
Is this supplement I’ve been given safe with my treatment?
Can we plan meals around my treatment days and my fasting days?
Who do I contact if I lose weight quickly or cannot keep food down?

The short version

There is a great deal of confident dietary advice circulating that isn’t based on evidence, and it costs patients money, pleasure and sometimes nutrition. What we can say with confidence is that a varied, balanced diet helps — and that getting the balance right matters far more than getting it perfect.

If you are unsure about a food, a supplement, or a diet you have read about, bring it to your appointment. Your care team knows your treatment and your history. That is a reasonable question to ask, and I would much rather answer it than have you work it out from the internet.

References

Rock CL, Thomson CA, Sullivan KR, et al. American Cancer Society nutrition and physical activity guideline for cancer survivors. CA Cancer J Clin. 2022;72(3):230–262.
Ligibel JA, Bohlke K, May AM, et al. Exercise, Diet, and Weight Management During Cancer Treatment: ASCO Guideline. J Clin Oncol. 2022;40(22):2491–2507.
NCCN Clinical Practice Guidelines in Oncology: Survivorship, Version 2.2025.
American Cancer Society. Guideline for Diet and Physical Activity for Cancer Prevention (alcohol recommendation).
World Cancer Research Fund / American Institute for Cancer Research. Diet, Nutrition, Physical Activity and Cancer: A Global Perspective.

This article gives general information and does not replace advice from your own care team. If anything here conflicts with what your doctor has told you, follow your doctor.