What Are the Calorie and Protein Requirements for People With Cancer?

During cancer treatment, there are some common barriers that prevent a person from getting enough calories and protein. For example, tumors involving the gastrointestinal system, chemotherapy, radiation therapy and the emotional impact that follows can all lead to unintentional weight loss.

If not overcome, these barriers can cause a person with cancer to lose lean muscle and can open the door to nutritional deficiencies. In fact, studies have reported malnutrition — when the body doesn't receive enough nutrients for proper function — in 20 to 70 percent of people with cancer, according to a research review in the October 2017 issue of Clinical Nutrition.

Since getting enough calories and protein helps facilitate health and recovery, it's essential that anyone with cancer focuses on filling their plate with nutrient- and calorie-dense foods as well as plenty of protein.

Read more: What to Eat to Boost Your Immune System During Chemo

Even with a cancer diagnosis, calorie needs differ from person to person. Energy requirements are dependent upon a variety of factors, including age, weight, height, physical activity level, medical conditions and the course of cancer treatment. The National Cancer Institute recommends that people in treatment for active cancer eat enough calories to prevent weight loss and improve their treatment outcomes.

There are several formulas dietitians use to estimate calorie needs, but the simplest is a calculation based on current weight. According to the October 2017 issue of Clinical Nutrition, calorie requirements for adults with cancer range between 25 to 30 calories per kilogram (2.2 pounds) of body weight per day.

So, someone who weighs 70 kilograms (154 pounds) should eat 1,750 to 2,100 calories a day. And someone who weighs 90 kilograms (198 pounds) needs around 2,250 to 2,700 calories each day. However, this range is a starting point and individual calorie needs may be higher or lower.

Protein is essential for maintaining good health — it aids in the formation, maintenance and repair of muscles and tissues, and is a vital component in nearly all body cells, including blood cells, enzymes, hormones and immune cells, per the Academy of Nutrition and Dietetics.

Read more: Protein 101: What It Is, Why It's Important and How to Get More

Most healthy people can easily get enough protein in their diet, but surgery and cancer treatment can increase protein requirements and make it harder for some people to meet these needs. The optimal amount of protein in people with cancer has not been determined, but recommendations often range between 1.2 to 1.5 grams per kilogram of body weight per day, according to nutrition and cancer guidelines established by The European Society for Parenteral and Enteral Nutrition (ESPEN), published in the February 2017 issue of Clinical Nutrition.

This translates to 84 to 105 grams for a person who weighs 70 kilograms (154 pounds), and 108 to 135 grams for a person weighing 90 kilograms (198 pounds). Higher amounts of protein may be needed in those who have had more muscle wasting or unintentional weight loss, and lower levels may be recommended for people with severe kidney disease.

A variety of foods are excellent sources of protein. For instance, you'll find an average of 24 grams protein in 3 ounces of cooked fish, chicken, pork or beef, and about 6 grams protein in 1 ounce of cheese or a large egg.

Cow's milk contains about 8 grams per cup and soy milk has 6 grams per cup. Other plant sources of protein include legumes, such as black or kidney beans (7 grams per half-cup cooked), peanut butter (7 grams per 2 tablespoons) and nuts (about 6 grams per ounce).

According to the National Cancer Institute, weight loss and malnutrition can lead to poor outcomes in people with cancer as a result of weakened immunity, increased infection risk and impaired response to cancer treatment. So anyone with cancer should prioritize eating well and take steps to ensure their body receives enough calories, protein and other nutrients in order to keep the body and immune system strong.

If you have a poor appetite or other treatment side effects that make it hard to eat adequately, there are many different strategies that can help.

Try smaller meals or snacks. The National Cancer Institute recommends eating several small meals throughout the day rather than attempting large meals. Alternatively, eat three daily meals in the size you can tolerate, and add a yogurt smoothie or liquid nutrition supplement (such as Ensure or Boost) in between your meals.

Focus on protein and carbs. Include high-protein foods at all meals and most snacks, and also include bread, crackers, tortillas, rice, pasta, potatoes, cereal or other grains at most meals. And eat fruits and vegetables for added nutrients throughout the day.

Add healthy fats. Sneak sources of calories and healthy fats into your meals and snacks, including olive oil, avocado, nuts and seeds.

After completion of cancer treatment, and assuming good health, calorie needs may be the same as other healthy adults without a history of cancer. According to the U.S. Dietary Guidelines 2015-2020, healthy women generally require 1,600 to 2,000 calories daily to maintain weight, and men require 2,000 to 3,000 per day.

Of course, individual calorie requirements can be more personalized and based on activity level, weight status, age and health status. The Recommended Dietary Allowance for protein in healthy adults is a modest 0.8 grams per kilogram of body weight, or 56 grams daily for a person weighing 154 pounds and 72 grams daily for someone weighing 198 pounds.

For long-term health after cancer treatment, a high-quality diet matters and may extend life in cancer survivors, according to research published in the December 2016 issue of Nutrition Reviews.

For people with a history of cancer, the Academy of Nutrition and Dietetics recommends a diet that emphasizes fruits, vegetables, whole grains, beans, lentils and nuts, and limits refined grains, added sugars, red meat and alcohol. This diet pattern is also heart-healthy and is linked to reducing the risk of other health problems. Since more research is needed in the area of nutrition and cancer survivorship, talk to your doctor and dietitian about a long-term eating plan that is right for you.

Read more: How to Calculate Protein RDA Best for Your Body