A pinboard by
Sarah Purcell

PhD Candidate, University of Alberta


Energy Expenditure in Cancer - One Size Does NOT Fit All

If you’ve ever tried on anything that says “one size fits all”, then you might know from experience, that one size certainly does not fit all. The same can be said for the amount of calories each person needs to maintain body weight. The amount of food someone should consume is determined by the energy they use, called energy expenditure (EE). Everyone has a different EE; for example, an ultra-marathoner might need over 6,500 calories while a small sedentary female might need about 1,500 calories to maintain body weight. There are certain conditions that may cause changes in EE- cancer is one of them. Many individuals with cancer have an EE that is too high and a dietary intake that is too low. This will lead to weight loss which is associated with higher fatigue, lower response to therapies, lower quality of life, and even shorter survival. Clearly, it's best to maintain weight during cancer treatment. About 40% of adults will be diagnosed with cancer during their lifetimes. Nutrition is an important part of handling treatment and recovery. Unfortunately, trying to make accurate dietary recommendations for each individual is like the blind leading the blind- we don’t know enough about what these patient's EE. My research will set the stage for understanding EE and thus dietary needs in cancer, by using state-of-the-art technology. One of these tools is a metabolic cart, which measures EE using the amount of oxygen and carbon dioxide collected under a hood system. I also use doubly labeled water, which requires a participant to drink a cup of safe and tasteless water with isotopes. The difference in disappearance of these isotopes allows me to objectively measure all of the calories used in a free-living environment- including the calories burned at rest, during activity, and even the calories used for digesting food. I will use these methods to describe EE in relation to what patients are eating, the amount of muscle and fat they have, quality of life, and physical activity, providing me with a comprehensive profile of nutrition status. For the first time, we will have a comprehensive profile of EE in cancer. This can be used to guide future dietary recommendations for weight maintenance. So many of us will be affected by cancer in our lifetimes. Just as "one size fits all" does not apply to clothing, it shouldn't apply to what individuals with cancer are told to eat.


Impact of Body Weight and Body Composition on Ovarian Cancer Prognosis.

Abstract: Measures of body weight and anthropometrics such as body mass index (BMI) are commonly used to assess nutritional status in clinical conditions including cancer. Extensive research has evaluated associations between body weight and prognosis in ovarian cancer patients, yet little is known about the potential impact of body composition (fat mass (FM) and fat-free mass (FFM)) in these patients. Thus, the purpose of this publication was to review the literature (using PubMed and EMBASE) evaluating the impact of body weight and particularly body composition on surgical complications, morbidity, chemotherapy dosing and toxicity (as predictors of prognosis), and survival in ovarian cancer patients. Body weight is rarely associated with intra-operative complications, but obesity predicts higher rates of venous thromboembolism and wound complications post-operatively in ovarian cancer patients. Low levels of FM and FFM are superior predictors of length of hospital stay compared to measures of body weight alone, but the role of body composition on other surgical morbidities is unknown. Obesity complicates chemotherapy dosing due to altered pharmacokinetics, imprecise dosing strategies, and wide variability in FM and FFM. Measurement of body composition has the potential to reduce toxicity if the results are incorporated into chemotherapy dosing calculations. Some findings suggest that excess body weight adversely affects survival, while others find no such association. Limited studies indicate that FM is a better predictor of survival than body weight in ovarian cancer patients, but the direction of this relationship has not been determined. In conclusion, body composition as an indicator of nutritional status is a better prognostic tool than body weight or BMI alone in ovarian cancer patients.

Pub.: 16 Jan '16, Pinned: 28 Jun '17

Key determinants of energy expenditure in cancer and implications for clinical practice.

Abstract: Great discrepancies exist in the reported prevalence of altered energy metabolism (hypo- or hypermetabolism) in cancer patients, which is likely due to the vast array of phenomena that can affect energy expenditure in these patients. The purpose of this review was to critically evaluate key determinants of energy expenditure in cancer and the relevance for clinical practice. Resting energy expenditure (REE) is the largest and most commonly measured component of total energy expenditure. In addition to the energetic demand of the tumor itself, REE may be increased due to changes in inflammation, body composition and brown adipose tissue activation. Energy expenditure from physical activity is often lower in cancer compared with healthy populations, and there is evidence to suggest that the thermic effect of food might also be blunted and affected by cancer therapy. Although accurate assessment of energy metabolism is a cornerstone of adequate nutritional therapy, prediction methods often do not capture the true energy expenditure of most cancer patients. In fact, limits of agreement of prediction equations may range from 40% below to 30% above measured REE. Such variability highlights the need for a more comprehensive understanding of energy expenditure in cancer and the value of accurately assessing the energy needs of these patients.European Journal of Clinical Nutrition advance online publication, 8 June 2016; doi:10.1038/ejcn.2016.96.

Pub.: 09 Jun '16, Pinned: 28 Jun '17

Impact of breakfast skipping compared with dinner skipping on regulation of energy balance and metabolic risk.

Abstract: Background: Meal skipping has become an increasing trend of the modern lifestyle that may lead to obesity and type 2 diabetes.Objective: We investigated whether the timing of meal skipping impacts these risks by affecting circadian regulation of energy balance, glucose metabolism, and postprandial inflammatory responses.Design: In a randomized controlled crossover trial, 17 participants [body mass index (in kg/m(2)): 23.7 ± 4.6] underwent 3 isocaloric 24-h interventions (55%, 30%, and 15% carbohydrate, fat, and protein, respectively): a breakfast skipping day (BSD) and a dinner skipping day (DSD) separated by a conventional 3-meal-structure day (control). Energy and macronutrient balance was measured in a respiration chamber. Postprandial glucose, insulin, and inflammatory responses in leukocytes as well as 24-h glycemia and insulin secretion were analyzed.Results: When compared with the 3-meal control, 24-h energy expenditure was higher on both skipping days (BSD: +41 kcal/d; DSD: +91 kcal/d; both P < 0.01), whereas fat oxidation increased on the BSD only (+16 g/d; P < 0.001). Spontaneous physical activity, 24-h glycemia, and 24-h insulin secretion did not differ between intervention days. The postprandial homeostasis model assessment index (+54%) and glucose concentrations after lunch (+46%) were, however, higher on the BSD than on the DSD (both P < 0.05). Concomitantly, a longer fasting period with breakfast skipping also increased the inflammatory potential of peripheral blood cells after lunch.Conclusions: Compared with 3 meals/d, meal skipping increased energy expenditure. In contrast, higher postprandial insulin concentrations and increased fat oxidation with breakfast skipping suggest the development of metabolic inflexibility in response to prolonged fasting that may in the long term lead to low-grade inflammation and impaired glucose homeostasis. This trial was registered at clinicaltrials.gov as NCT02635139.

Pub.: 12 May '17, Pinned: 28 Jun '17