Unintentional weight loss is common in cancer patients. Several factors can cause weight loss, including the type of cancer treatment, side effects, physical changes related to the tumor’s location and the emotional impact of cancer. Additionally, cancer cells themselves can play a direct role in weight loss.
Fortunately, there are steps that patients can take to combat cancer-related weight loss.
Treatment-related weight loss
Cancer treatments such as chemotherapy, radiation therapy, surgery, immunotherapy and stem cell transplantation may result in conditions that can cause weight loss. These conditions include:
Mouth and throat sores: Also called mucositis, these are the most common cause of cancer weight loss. Sores are caused by chemotherapy and radiation, which attack cancer cells. Unfortunately, healthy cells are also impacted. These include cells that line the mouth and throat. As a result, many patients develop painful sores in these areas, making it harder for them to eat. Learn more about oral care for cancer patients.
Loss of appetite: In some cases, chemotherapy affects a person’s appetite and sense of taste, making food unappealing. Learn more about appetite changes.
Diarrhea: Chemotherapy, radiation, immunotherapy, surgery and targeted therapy can cause diarrhea. Unintended weight loss can result from persistent or chronic diarrhea. Learn more about bowel management.
Nausea and vomiting:
Nausea and vomiting may occur anywhere from a few hours after treatment to several weeks later. They may be more severe in patients receiving a combination of treatments, such as chemotherapy and radiation therapy together.
Chemotherapy-induced nausea and vomiting (CINV) is an extremely common side effect. Sometimes nausea and vomiting are worse with higher doses of the medications. Not all chemotherapy medications cause nausea and vomiting.
Radiation therapy can cause nausea and vomiting. This is most common during treatment to the brain or the abdomen.
Other causes of cancer-related weight loss
Early satiety: Many patients complain that they want to eat but then feel full after only a few bites of food. This may be related to cancer treatments and/or the cancer itself. Cancer cells sometimes release hormones that alter the sensation of hunger. Other times, tumors in the gastrointestinal tract or fluid in the abdominal cavity may cause a patient to feel full after only a small amount of food.
Constipation: Constipation in cancer patients can be caused by:
- Opioid pain medication
- External compression or internal obstruction of the bowel by a tumor
- Medications such as antacids and iron
- Abnormal electrolyte levels, including calcium and potassium levels
- Decreased physical activity
Constipation may cause a patient to feel full and lose the desire to eat. It can also cause nausea and vomiting, which leads to decreased nutritional intake. Learn more about bowel management.
Pain: Patients battling cancer often experience pain. Uncontrolled pain can cause decreased appetite. Learn more about cancer pain.
Emotional distress: Depression typically causes a person to lose interest in activities such as eating. It may also lead to lack of motivation to exercise, which helps maintain muscle tone and weight. Anxiety can lead to weight loss by causing a general loss of appetite. Anxiety also can lead to diarrhea, and increase muscle tension and movement, which burns calories. Learn more about stress reduction.
Cancer-related inflammation: Cancer patients often have heightened inflammation. The immune system then releases proteins that hinder the hormones that stimulate appetite and alter metabolism, leading to weight loss.
Treating cancer-related weight loss
Some medications can help stimulate your appetite and ease the side effects of cancer treatment. Your health care team may recommend medications to stimulate the appetite and/or to treat nausea, vomiting and early satiety.
The best way to give your body enough nutrients is through food. In some cases, though, patients cannot eat or eat enough to maintain their weight. These patients may get nutrition through a tube inserted through the nose or abdomen into the stomach. This is called enteral feeding. It is typically only for short-term use and has risks including aspiration (food or liquid entering the lungs) and unintentional tears in your esophagus, stomach or intestines. These tubes can also be uncomfortable.
Sometimes, patients receive nutrients through a vein instead of eating and drinking if the gastrointestinal tract is not functioning or cannot be used. This is called parenteral nutrition. The safety and effectiveness of this method is not clear, and there are serious potential complications including blood clots and infection.
The use of either enteral feedings or parenteral nutrition should start with a discussion between a patient and their doctor and involve collaboration with a nutrition team.
General tips to manage and prevent weight loss
- There are several steps patients can take on their own to maintain their weight.
- Rather than having three big meals a day, focus on eating frequent, small meals every two to three hours.
- Incorporate supplement drinks to increase your intake of protein and calories. You can also make your own smoothies at home using high-protein milk and/or protein powder. Both animal-based and plant-based protein powders are readily available.
- While it is important to drink plenty of fluids, try to do this in between meals to avoid feeling full easily when eating.
- If water is not appealing, try other sources of fluids. These can include soup, fruits like watermelon and sports drinks (depending on your blood sugar levels). You may also add flavor to water with natural fruit juices or water flavoring drops.
- Eat food rich in both calories and protein, such as avocados, peanut butter, nuts and yogurt.
- Try experimenting with different flavors such as salty, sour and sweet. A flavor that you did not like before may be enjoyable now.
- Ask your doctor about a referral to a nutritionist/dietician who can assess your nutritional status and give advice on increasing your intake of calories and protein.
- Track your bowel movements and report any changes to your health care team.
- If you are having problems chewing and swallowing, ask your doctor about an evaluation by a speech pathologist. Speech pathologists can recommend a diet that is appropriate for your condition.
- Prevention is important when it comes to mouth and throat sores. Your doctor can advise you about whether treatment can cause sores and how to modify your oral hygiene regimen to prevent them.
- Address both physical and emotional symptoms. Talk to your health care team If you experience emotional changes such as prolonged sadness and/or anxiety that are interfering with your day-to-day life or desire to eat.
Whether it’s due to pain from a growing tumor, swallowing difficulties caused by radiation therapy, or the nausea, loss of appetite or mouth sores that are sometimes caused by chemotherapy, involuntary weight loss is a serious side effect of cancer and its treatment for many patients.
But there are other reasons why cancer patients could be losing weight without trying.
We spoke with internal medicine and palliative care specialist Rony Dev, D.O., to learn more about involuntary weight loss and what patients can do to counteract this common side effect. Here’s what he had to say.
What are the most common causes of involuntary weight loss in cancer patients?
The simplest answer is “decreased caloric intake.” They just aren’t eating as much. And when you don’t take in enough calories for your body to maintain itself, weight loss is the result. There are quite a few things that contribute to weight loss in addition to the underlying cancer.
For one thing, the body secretes inflammatory proteins, including “tumor necrosis factor” (TNF), which make people feel bad and typically experience a significant decrease in their appetite.
Trying to control cancer requires a lot of energy, too, and cancer patients’ metabolism is often elevated to accommodate for the increased inflammatory response. That combination alone is enough to cause weight loss, but when you combine it with the appetite-suppressing qualities of pain, changes in the taste of food (often described as being metallic) due to chemotherapy, and the discomfort caused by constipation and reflux issues, the issue of weight loss is often compounded.
Mood disorders, depression and anxiety can also contribute to weight loss. In addition, there are endocrine factors, such as low testosterone, that can cause changes in body composition and a decrease in weight in male patients with certain cancers or on chronic opioid therapy.
What can doctors do to help patients counteract involuntary weight loss?
Fortunately, there are treatments especially for symptoms that can contribute to weight loss. We can use beta-blockers to treat hypermetabolism; antiemetics for combatting nausea; counseling, anxiolytics (drugs used to treat anxiety) and antidepressants for stress and mood disorders; anti-inflammatories to reduce inflammation, and hormonal supplements to replace testosterone in male patients.
What can patients do to manage involuntary weight loss?
Most interventions require a health care provider, so it’s important to communicate with your care team as soon as you notice a problem. They can enlist the help of any specialists you might need, such as a dentist for tooth pain or chewing problems, and a gastroenterologist for help with bowel issues.
Why is it important for cancer patients to get unwanted weight loss under control quickly?
Patients tolerate cancer treatment better and have better responses to it if they can maintain a healthy weight. So, adequate caloric intake is critical to preventing chronic undernourishment.
Unwanted weight loss can also lead to fatigue, which means patients aren’t able to do all of the things they want to do. That causes a lot of distress — not only in patients, but also in their caregivers.
That’s why it’s so important to catch this problem early. If someone loses 5% or more of their total body weight without trying, that’s a big red flag. And we need to start addressing some of those underlying factors right away, before it snowballs.
Is involuntary weight loss more common in patients with certain types of cancers?
Yes. More than 80% of patients with pancreatic cancer will experience unwanted weight loss. It’s fairly common in other gastrointestinal cancers, too. And we’re also more likely to see it in advanced cancers, regardless of the type.
Are there any clinical trials underway related to involuntary weight loss?
Yes. One clinical trial is assessing psychological factors associated with weight loss. It deals with the frequency of cancer-induced anorexia (loss of appetite) and cachexia (wasting disease) in patients with anxiety and depression, and assesses body composition and takes other mitigating factors into account.
A second clinical trial is studying whether a drug called anamorelin can spur weight gain by manipulating the appetite hormone, ghrelin.
What’s the one thing you want cancer patients to know about involuntary weight loss?
Once dramatic weight loss has occurred, it’s very hard to change course. So, seek help as soon as you notice it happening.
Request an appointment at MD Anderson online or by calling 1-877-632-6789.