Final answer:
Individuals with COPD are at a higher risk of malnutrition primarily due to increased energy expenditure from the effort required to breathe adequately, which leads to greater caloric needs and potential weight loss.
Step-by-step explanation:
The most likely reason why a client with Chronic Obstructive Pulmonary Disease (COPD) is at higher risk of malnutrition is due to increased energy expenditure used to maintain adequate breathing. COPD is characterized by chronic poor airflow and damage to the lungs over the long term, leading to difficulties in breathing and reduced gas exchange efficiency. The effort required for breathing in individuals with COPD is significantly higher and can lead to an increased caloric need. This increased demand for energy coupled with factors like reduced appetite, difficulty in eating, and potential gastrointestinal issues can lead to malnutrition and weight loss.