Malnutrition: Causes, Symptoms, and Treatment
Written by Sumiran Racherla, MD. Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Malnutrition?
A primary care doctor usually starts the exam. You may then see a dietitian, an expert in food and nutrition. A gastroenterologist, a doctor who treats the gut, can help if digestion is part of the problem. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is malnutrition?
Malnutrition is the condition that occurs when your body does not get enough nutrients. Nutrients are the vitamins, minerals, and other things your body needs from food. The word means "poor nutrition."
The World Health Organization says malnutrition can mean too little, too much, or an imbalance of energy and nutrients. It includes undernutrition, vitamin and mineral problems, and overweight and obesity. The sections below focus mostly on undernutrition, which is not getting enough nutrients.
Sometimes malnutrition is very mild and causes no symptoms.
Symptoms
Symptoms vary and depend on the cause. General symptoms include fatigue, dizziness, and weight loss. Other signs include:
- Weight loss without trying. Losing 5% to 10% or more of your weight over 3 to 6 months is a main sign.
- A low body mass index (BMI). A BMI under 18.5 means a person is at risk.
- Little interest in eating and drinking.
- Feeling tired all the time or feeling weak.
- Getting ill often and taking a long time to recover.
- In children, not growing or not gaining weight at the expected rate.
Causes and who gets it
There are many types of malnutrition, and they have different causes. Some causes include a poor diet, starvation due to food not being available, and eating disorders. Others are malabsorption, or trouble absorbing nutrients from food. Some medical conditions can also make a person unable to eat.
You may develop malnutrition if you lack a single vitamin in your diet. Poverty, natural disasters, political problems, and war can also add to it.
Anyone can become malnourished. Risk is higher in people who:
- Have long-term health conditions that affect appetite, weight, or how well nutrients are absorbed. Crohn's disease is one example.
- Have trouble swallowing.
- Are isolated, have limited mobility, or have a low income.
People 65 and over are particularly at risk. Children under the age of five are also at risk. It is very harmful to children, because it affects brain development and other growth.
How doctors diagnose it
Testing depends on the specific disorder. Most providers will do a nutrition assessment and blood work.
A doctor can check your risk by measuring your weight and height. They also ask about your medical problems and any recent changes in your weight or appetite. If they think you could be malnourished, they may refer you to a dietitian.
Treatment
Treatment depends on your general health and how severe the problem is. It most often means replacing missing nutrients. It also means treating symptoms and any health problem behind it.
The first advice is usually to eat fortified foods that are high in calories and protein. You may also snack between meals and have drinks that contain lots of calories. A doctor, nurse, or dietitian may add nutrition drinks or supplements.
If soft or liquid foods are not enough for trouble eating, a feeding tube may be used. Nutrition can also be given directly into a vein. If a child is malnourished, the family may need advice and support.
Most nutritional deficiencies can be corrected. If an illness causes the problem, that illness has to be treated to reverse it. If untreated, malnutrition can lead to mental or physical disability, illness, and possibly death.
When to see a doctor
Treatment is necessary if you or your child have any changes in the body's ability to function. Contact your provider if you have a lack of menstruation or rapid hair loss. Also call if a child is not growing.
Call 911 or go to the emergency room if you faint or lose consciousness, have trouble breathing, have chest pain or discomfort lasting two minutes or more, are confused or hard to wake, or have severe or ongoing vomiting or diarrhea.
See a doctor if you lost a lot of weight without trying over the last 3 to 6 months. Also go if you have other signs of malnutrition. See a doctor too if you worry that a child or older person in your care is not eating enough.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. A DPC doctor can measure your weight, review your diet, and order blood work. They can also refer you to a dietitian or specialist and follow your progress.
Common questions
Can malnutrition happen in people who are overweight?
Yes. Malnutrition can also include overweight and obesity, according to the World Health Organization.
Can malnutrition be treated?
Yes. Most nutritional deficiencies can be corrected. If an illness is the cause, that illness has to be treated too.
Can malnutrition be prevented?
Often, yes. Eating a well-balanced diet helps to prevent most forms of malnutrition. Speak to a doctor if a health problem puts you at higher risk.
Is malnutrition dangerous?
It can be. If untreated, malnutrition can lead to mental or physical disability, illness, and possibly death.
Sources
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
