Cancer Cachexia & Muscle Wasting Prevention

Some people lose weight during cancer treatment because they are eating less. Others lose muscle while still eating reasonably well. The stairs get harder. A full grocery bag feels heavy. Standing up from a low chair takes a push off the armrest. The second pattern is not simply the first one made worse. Knowing the difference helps you know what to expect from the advice you get. This page explains cancer cachexia, why eating more does not fix it, and what to tell your care team.

The National Cancer Institute describes cancer cachexia in its patient materials. It is a wasting syndrome (a group of symptoms) that can cause weakness, weight loss, and loss of fat and muscle. What surprises most people is that it can happen even when you are eating well.

NCI's version for health professionals is more precise. Cachexia is a multifactorial syndrome. It means an ongoing loss of skeletal muscle (the muscles that move your body) that normal nutrition support cannot fully reverse, and it leads to steadily worse function. Each part of that matters:

• Multifactorial means there is no single cause to correct.
• Ordinary nutrition support does not fully reverse it.
• What gets measured is function, meaning what you can do, not a number on a scale.

NCI describes three stages:

• Precachexia: early metabolic signs (changes in how the body uses energy) appear before much weight is lost.
• Cachexia: there is significant weight loss or sarcopenia, and it is not simple starvation.
• Refractory cachexia: the syndrome resists treatment. It is usually seen in advanced-stage cancer.

You may hear the related term sarcopenia. NCI defines it as the condition of severe muscle depletion. It is reported to occur in 50% of patients with advanced cancer. NCI also cites a meta-analysis on this. A meta-analysis combines the results of many studies. It found that a low skeletal muscle index (a measure of muscle size) at cancer diagnosis was linked to worse survival in patients with solid tumors.

This part is worth saying plainly, because well-meaning family members often push food harder as weight falls. NCI states that more calories have failed to counteract the wasting process. That holds whether the calories come by mouth or by total parenteral nutrition, which means feeding through a vein. Anorexia (loss of appetite) may also be present, NCI notes. But the energy shortfall alone does not explain how cachexia develops.

The reason is that inflammation signals in the body are driving the muscle loss. NCI names substances made by the body's own tissues as the drivers of this complex syndrome. They include tumor necrosis factor-alpha, interleukin-1, interleukin-6, interferon-gamma, and leukemia inhibitory factor.

No treatment in the NCI material reviewed here reliably reverses established cachexia. NCI's patient page mentions that you may also take medicines that increase appetite. But appetite medicines target intake, not the muscle loss itself. NCI does not present them as a cure for the syndrome. Someone may offer you a supplement or protocol that promises to rebuild lost muscle during active cancer. Treat that promise with suspicion.

That does not mean nothing is worth doing. Poor intake makes everything worse, and it can be fixed. NCI describes the goal of nutrition screening: to find quickly the patients at risk of malnutrition, and to refer them to a health care professional, ideally a registered dietitian. NCI also notes research on how long that takes. The median time from cancer diagnosis to dietitian referral was 61 days. You do not have to wait for that referral to be offered.

NCI's appetite guidance is specific:

• Eat small meals every 2 to 3 hours, about 5 or 6 meals per day.
• Eat within 1 hour of waking up.
• Eat foods high in protein and calories.
• Eat the high-protein foods first, while your appetite is strongest.
• If solid food does not appeal, drink milkshakes, smoothies, juices, or soups.
• Sip nutrition supplement drinks between meals, such as Ensure and Boost.

If nausea is what stops you eating, that is a treatable problem in its own right. Our nausea and appetite loss page covers it. Weakness also has causes other than muscle loss. NCI lists weak or achy muscles and muscle wasting among the effects of motor nerve damage from treatment. That is a different problem, and it is managed differently.

• Weight loss. NCI says to speak with them right away if you start to lose weight, and to report weight loss of more than 3 to 5 pounds in one week to your doctor.
• The American Cancer Society suggests paying attention if you lose more than 5% of your body weight in a year without trying, and contacting your team about rapid loss of more than 3 pounds in a week.
• Severe fatigue that leaves you unable to do your usual activities.
• Any symptom that is keeping you from eating, such as pain, nausea, mouth problems, or feeling full quickly.

Ask directly for a referral to a registered dietitian. It is a standard cancer service. You do not need a crisis first.

• Call your care team right away if your legs have become too unsteady to stand or walk on safely, or if you have already had a fall. Weakness that changes over days is different from weakness that has crept up over months. For emergencies call 911 or go to the ER.
• Call your care team right away if the scale drops more than 3 pounds in a week, which the American Cancer Society says can be a sign of dehydration, or if you feel weak, very tired or dizzy and your usual day is out of reach. NCI says to speak with your team right away if you start to lose weight.
• Call your care team right away if something physical is blocking you from eating or drinking at all — pain, sickness, a sore mouth, or feeling full after a few bites. That is a fixable problem, and fixing it early protects the muscle you still have.

• National Cancer Institute — Nutrition in Cancer Care (PDQ), Health Professional Version: https://www.cancer.gov/about-cancer/treatment/side-effects/appetite-loss/nutrition-hp-pdq
• National Cancer Institute — Nutrition in Cancer Care (PDQ), Patient Version: https://www.cancer.gov/about-cancer/treatment/side-effects/appetite-loss/nutrition-pdq
• National Cancer Institute — Appetite Loss and Cancer Treatment: https://www.cancer.gov/about-cancer/treatment/side-effects/appetite-loss
• National Cancer Institute — Nerve Problems (Peripheral Neuropathy) and Cancer Treatment: https://www.cancer.gov/about-cancer/treatment/side-effects/nerve-problems
• American Cancer Society — Weight Changes: https://www.cancer.org/cancer/side-effects/eating-problems/weight-changes.html