The short answer
After stomach surgery food reaches the intestine faster, which explains dumping syndrome, weight loss and poor absorption. If the upper part of the stomach was removed, vitamin B12 tablets are not absorbed and B12 is given by injection instead.
In a total gastrectomy the surgeon joins the esophagus straight to the small intestine, so food arrives faster and in a different state than before.
Nausea, diarrhoea, sweating and flushing soon after eating is dumping syndrome. Small portions every two to three hours and staying upright after meals are the usual first steps.
If the upper part of the stomach was removed, vitamin B12 tablets are not absorbed and B12 is given by injection, with regular blood work for vitamin and mineral levels.
The American Cancer Society describes visits every three to six months for the first few years, with an exam and symptom review, plus blood tests or upper endoscopy when ordered.
On this page
Choose how you want to read this
The whole article, with every detail and caution.
This page is for people who have finished treatment for stomach cancer. It covers eating after stomach surgery, vitamin needs, weight, follow-up checks, family risk, and questions for your visits.
Eating after part or all of the stomach is gone
Stomach cancer surgery removes part of the stomach, or all of it. NCI describes both. In a total gastrectomy the surgeon joins the esophagus straight to the small intestine so you can still eat and swallow.
That rerouting explains almost everything that follows. Food arrives in the intestine faster and in a different state than before.
Ask which operation you had, and how much stomach is left.
The rush of symptoms after a meal
Nausea, diarrhea, sweating and flushing soon after eating has a name. The American Cancer Society calls it dumping syndrome, and explains it as swallowed food passing quickly into the intestine.
It usually improves with time. Some people still need medicine for lasting diarrhea.
ACS says a registered dietitian can help you adjust to smaller, more frequent meals. Ask for one rather than working it out alone.
The vitamin problem
If the upper part of your stomach was removed, vitamin B12 in tablet form is not absorbed. The American Cancer Society says so directly, and describes B12 by injection instead.
ACS also says people who have had upper stomach removal often need regular blood work to check vitamin levels.
Ask which levels are being checked and how often.
Weight, strength and feeding tubes
ACS notes that weight loss and appetite changes are common after treatment. Ask what weight change you should report, and whether a dietitian can help.
How often the checks happen
The American Cancer Society describes follow-up visits every three to six months for the first few years, then less often.
Those visits include an exam and a review of symptoms. ACS says lab work or imaging may also be done. NCI says tests used at diagnosis may be repeated, and blood tests may check tumor markers such as CEA and CA 19-9. Ask which tests apply to you.
Ask for your own schedule in writing.
If this cancer runs in your family
Ask your care team whether your family history matters for you or your relatives, and whether genetic counseling is worth discussing.
Questions for the follow-up visit
- Which operation did I have, and how much stomach is left?
- Will I need B12 injections, and for how long?
- Which vitamin levels are checked, and how often?
- What can I do about symptoms right after eating?
- Can I see a dietitian this month?
- How often will I have blood tests or imaging?
- Should my family have genetic counseling?
Related pages
Cancer Staging and Biomarker Testing explain the terms that show up in stomach cancer follow-up notes. Clinical Trial vs Standard Treatment, Palliative Care, and Questions to Ask Your Doctor cover what to raise at a stomach cancer survivorship visit.
Where this comes from
These questions were drawn from current patient guidance for stomach cancer:
Common questions
Why do I feel awful right after eating?
That mix of nausea, diarrhoea, sweating and flushing is dumping syndrome, caused by swallowed food passing quickly into the intestine. It usually improves with time, though some people still need medicine for lasting diarrhoea.
Will I need B12 injections?
Probably, if the upper part of your stomach was removed, because B12 in tablet form is not absorbed then. The American Cancer Society says some people need vitamin supplements, which can include B12 injections. Ask which other vitamin and mineral levels are checked, how often, and what a low result would feel like.
What happens if I cannot eat enough?
A tube into the small intestine, placed through a small opening in the abdomen, can carry the load. Ask what would make your team suggest one, and what it takes to come off it.
Questions to ask your doctor
Being prepared helps you get the most out of your appointments. Save or print these questions.
Tap a question to save it to your list (kept on this device).
Your next step
Turn this topic into questions for your next appointment.
Talk with a trained specialist or navigator
Cancer Explained provides educational guidance, but does not replace trained specialists, social workers, or your medical team.
Talk to a trained cancer information specialist
Free, confidential assistance from NCI Cancer Information Service via phone, chat, or email.
Contact your oncology team
Locate after-hours contact numbers, portal messages, or urgent triage phone lines.
Find a patient navigator
Get one-on-one help with appointments, logistics, translation, and care coordination.
Find a genetic counselor
Discuss inherited mutation risk, family history, and genetic testing options.
Find an oncology social worker
Access emotional counseling, family support groups, and mental health resources.
Find a financial navigator
Locate copay assistance foundations, grant programs, and lodging/travel support.
Find a clinical-trial specialist
Search matching studies and speak with NCI trial information specialists.
Get urgent help
Fever of 100.4°F (38°C) or higher during chemo, severe pain, or trouble breathing: call your cancer care team right away, day or night. Call 911 for an emergency.
Know someone who needs this?
Plenty of people are looking for something like this and do not know where to start. If this would help a friend or someone you love, send it on — we have written an opening line so you do not have to stare at an empty message. You can change every word of it.
Your message is written and sent in your own email or messaging app — we never see who you send it to, and nothing is added to any list.
Plain-language explanation of the published sources cited on this page. AI-assisted, source-checked, not clinician-reviewed.
Sources last checked: 2026-07-30 what this meansLast updated: 2026-10-02Next planned review: 2028-07-30
Review details and limits
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status — Source checked. This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
General education — varies by person. Answers genuinely differ between people. This page explains what commonly varies and points you to your care team for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
Words to know
Tap any term to see what it means.
How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
Read more about our editorial process, our use of AI, and our corrections policy.
Spotted a problem? Report an error — a factual mistake, broken or outdated source, confusing wording, or anything that seems unsafe. Please do not include names, medical record numbers, dates of birth, addresses, or other identifying medical information in your report.
After using this page, do you understand what to do next?
Anonymous — we only record the answer, never who gave it.
Related articles
- What Is Stomach Cancer? Where It Starts
- Cancer Staging: What the Stage Means
- Biomarker Testing and Precision Medicine
- Getting a Second Opinion After a Diagnosis
- Questions to Ask About Stomach Cancer Treatment
- Stomach Cancer Recurrence: What to Ask
- Metastatic Stomach Cancer: What to Ask
- Cancer Survivorship and Life After Treatment