Registered dietitian, Annica Rust, educates us on the role our metabolism and weight play during cancer treatment.
All human beings have individualised metabolisms that provide our cells with energy to sustain life.1 Our metabolism breaks down nutrients, such as carbohydrates, proteins, and fat to produce energy.2
Our body weight is influenced by energy balance (energy intake and energy expenditure) as shown in Figure 1. Total energy expenditure or energy outflow can be influence by: food-induced thermogenesis (the process to produce heat through digestion), energy expanded by physical activity and metabolic rate (basal metabolic rate – BMR).5
Basal metabolic rate
BMR is the energy required to sustain normal body functions and physiological processes.2 Factors that affect BMR include: age, body composition, body size, climate, gender, hormonal status and other factors, such as nicotine, alcohol and caffeine, which stimulates the metabolic rate.2
Every person will thus have a unique BMR as a baseline, regardless of their diagnosis, the presence of disease, intent of treatment (curative, control or palliative), anticancer therapy (surgery, chemotherapy, radiation or biotherapy), presence of fever or infection, or other metabolic complications.2
It’s important to determine a patient’s energy requirements, to provide individualised dietary recommendations to help maintain their energy balance and to achieve a healthy weight to prevent unintentional weight loss or gain caused by cancer and its treatment.2
Patients undergoing treatment are usually not encouraged to lose weight, but rather to maintain their weight and to lose weight, if necessary, after the treatment is completed.
Energy and protein requirements are often increased by the disease itself (cancer) and the subsequent treatment thereof.2 Protein requirements are increased to repair the tissue that has been damaged by chemotherapy.
Inadequate energy intake will result in the breakdown of lean body mass, which leads to the inability of the body to supply the necessary energy.2 Adequate energy intake prevents malnutrition, thus is crucial for a speedy recovery and can reduce the length of a hospital stay.4
A healthy body weight is important as obesity is a risk factor for cancer and accounts for almost 14-20% of all cancer related mortality. The underlying mechanisms for cancer mortality are weight dependant, such as insulin resistance, inflammation, oxidative stress, modulation of sex steroids, gut hormones and immune system. Overweight and obese survivors are thus at an increased risk for cancer reoccurrence and for developing additional problems after surgery, which includes impaired wound healing and lymphoedema.2
The American Cancer Society (ACS) sets out recommendations for controlling weight and preventing cancer.3
Table 1. 2020 American Cancer Society Guideline on Diet for Cancer Prevention3
1. Follow a healthy eating pattern at all ages. A healthy eating pattern includes: * Foods that are high in nutrients in adequate portions; * A variety of vegetables – dark green, red, orange, fibre-rich legumes (beans & peas) and others; * Fruits, especially whole fruits with variety of colours and whole-grains. A healthy eating pattern limits or doesn’t include: * Red and processed meats; * Sugar-sweetened beverages; or * Highly-processed foods and refined grained products.
2. It is best not to drink alcohol.* People who do choose to drink alcohol should limit their consumption to no more than one drink per day for women and two drinks per day for men.
A unique metabolism in combination with cancer and its treatment will thus influence your weight. There is no one size fits all approach. Accordingly, it’s recommended that you contact a registered dietitian for weight management and an individualised meal plan for cancer prevention, treatment, survivorship and palliation.
- Judge, A. & Dodd, MS. 2020. Metabolism. Essays in biochemistry, 64(4).
- Mahan, L.K. & Raymond, J.L. (eds). 2017. Krause’s food and the nutrition care process. 14th ed. St Louis. MO: Elsevier Saunders.
- Rock, C.L., Thomson, C., Gansler, T., Gapstur, S.M., McCullough, M.L., Patel, A.V., Andrews, K.S., Bandera, E.V., Spees, C.K., Robien, K., Hartman, S., Sullivan, K., Grant, B. L., Hamilton, K. K., Kushi, L.H., Caan, B.J., Kibbe, D., Black, J.D., Wiedt, T.L., McMahon, C., Sloan, K., Doyle, C. 2020. American Cancer Society Guideline for Diet and Physical Activity for Cancer Prevention. CA: Cancer Journal for Clinicians, 70(4).
- Leandro-Merhi, V.A., de Aquino, J.L.B., de Oliveira, M.R.M. 2016. Nutrition Status and Length of Hospital Stay. Diet and Nutritionin Critical Care,1(1).
- Heaney J. 2013. Energy: Expenditure, Intake, Lack of. In: Gellman M.D., Turner J.R. (eds) Encyclopedia of Behavioral Medicine. Springer, New York, NY. https://doi.org/10.1007/978-1-4419-1005-9_454
MEET THE EXPERT – Annica Rust
Annica Rust is a registered dietitian practicing at the Breast Care Unit in Netcare Milpark Hospital as well as in Bryanston. She assists with medical nutritional therapy for cancer prevention, treatment, survivorship and palliation. She gives individualised nutritional care to prevent or reverse nutrient deficiencies, nutrition-related side effects and malnutrition to maximise quality of life.