Patients who are experiencing malnutrition are not always underweight.
Bias surrounds the idea that patients with obesity cannot possibly be malnourished, according to Stacy Pelekhaty, MS, RDN, LDN, a senior clinical nutrition specialist in the Department of Clinical Nutrition at the University of Maryland Medical Center’s R. Adams Cowley Shock Trauma Center, in Baltimore. “Because they may not be recognized as malnourished, they may not receive optimal care.”
Ms. Pelekhaty and other experts spoke about diagnosing and managing malnutrition in patients with obesity, and its complicated and specific challenges, in a recent webinar during the American Society for Parenteral and Enteral Nutrition’s (ASPEN’s) Malnutrition Awareness Week.
Certain patients with obesity “are at high risk for malnutrition and should be screened for such, much like those in low and healthy BMI classes,” said Carolyn Newberry, MD, the director of the GI nutrition program in the Department of Gastroenterology at Weill Cornell Medical Center, in New York City. “Nutritional support interventions improve outcomes in those who are at high nutritional risk.”
Data show how patients with obesity are less likely to receive a diagnosis of malnutrition and to receive nutrition support. A 2022 review noted that patients with malnutrition and obesity were less likely than those with malnutrition and a body mass index in the normal or underweight categories to have a malnutrition diagnosis coded (Crit Care 2022;26[1]:283). In a 2014 multicenter cohort study involving more than 3,200 patients, the researchers found that initiation of nutritional support was delayed in obese ICU patients compared with low-weight, normal-weight and overweight patients (Am J Clin Nutr 2014;100[3]:859-866).
“There is often the assumption that patients with obesity, particularly significant obesity, can just ‘live off their fat.’ It doesn’t work that way. These patients are not well equipped to utilize their endogenous stores of nutrition during periods of critical illness, so they will mobilize both lean and fat tissues during stress metabolism,” Ms. Pelekhaty said.
Sarcopenic Obesity and Malnutrition
One condition to watch out for is sarcopenic obesity, which falls into the chronic disease malnutrition spectrum, Dr. Newberry explained. Although most people lose skeletal muscle as they age, patients with sarcopenic obesity lose lean muscle mass more quickly, while also holding on to adipose tissue, she said. “These kinds of body composition changes can have significant health implications,” she said. “The reality is that many of these people are already at an enhanced level of metabolic stress and may be at increased nutritional risk, depending on other disease comorbidities and dietary quality.”
However, sarcopenic obesity is not well defined. In addition, bedside measurement of muscle is not easy, noted Carrie P. Earthman, PhD, RDN, a professor of nutrition in the Department of Health Behavior and Nutrition Sciences at the University of Delaware, in Newark. “The most commonly used methods are CT scanning, ultrasound and bioimpedance techniques, with the last two being the best candidates as they can be used for repeated measures at the bedside, while CT is expensive, involves high doses of radiation and [offers] limited opportunity for measuring response to nutrition, given that it is done mainly for diagnostic purposes.
“In all of these methods, however, it’s important to remember that techniques are primarily validated in healthy people, and the underlying assumptions can be violated in disease. In people with obesity, factors such as expanded extracellular water can also introduce error.”
Guidance for Nutritional Support
The ASPEN guidelines on nutritional support in hospitalized adults with obesity recommend nutritional assessment and development of a nutritional support within 48 hours of ICU admission. First, providers should assess the patient’s risk for malnutrition. “Nutritional risk stratification is very important in these patients, and there are a number of basic risk stratification tools available,” Dr. Newberry said. These include the Nutritional Risk Screening 2002 for inpatients and the Malnutrition Universal Screening Tool for the outpatient setting (JPEN J Parenter Enteral Nutr 2013;37[6]:714-744).
“Although low [BMI] is an important diagnostic criteria for malnutrition, percentage total body weight loss from initial BMI and recent volitional intake and presence of acute and chronic disease can help identify patients with elevated BMI at equal or even increased risk,” Dr. Newberry said.
After a patient has been deemed at risk, there are several methods to determine the patient’s daily energy requirements (see box).
Nutritional support interventions have been shown to improve outcomes in patients at high nutritional risk, according to Dr. Newberry. “Evidence-based delivery of protein and calories in this population is imperative to enhance care,” she said. She noted that patients who derive the most benefit from nutritional therapy are those with a BMI below 25 kg/m2 and those with a BMI above 35 kg/m2 (Intensive Care Med 2009;35[10]:1728-1737).
“It is very important to understand that patients with elevated BMI are likely to have more complications than those with normal BMI,” Dr. Newberry said, “so we must continue to nutritionally assess them and have a nutritional support plan in place.”
—Gina Shaw
Dr. Newberry reported a financial relationship with InBody. Dr. Earthman and Ms. Pelekhaty reported no relevant financial disclosures.
This article is from the November 2023 print issue.