The nurse is teaching a patient about vegetarian diets. Which of the following is a potential health benefit of following a well-planned vegetarian diet?

Choice A reason: Physical activity level influences energy expenditure but is secondary in unexplained weight loss. Low activity may contribute to muscle loss, but it does not directly indicate nutritional status or underlying causes like malnutrition or disease, which are more urgent to assess in a 65-year-old.

Choice B reason: Blood albumin levels (3.5-5.0 g/dL) reflect protein status and nutritional health, critical in unexplained weight loss. Low albumin indicates malnutrition or illness (e.g., cancer, liver disease), which may cause weight loss in older adults, making it the priority assessment to guide diagnosis and intervention.

Choice C reason: Current medications can cause weight loss (e.g., diuretics), but their impact is secondary to nutritional status. Assessing medications provides context but does not directly measure protein deficiency or disease, which albumin levels better indicate in the context of unexplained weight loss.

Choice D reason: Family history of chronic illness informs long-term risk but is not immediate in assessing recent weight loss. It provides background for conditions like cancer but does not directly address current nutritional or metabolic status, making it less urgent than albumin levels.

Choice A reason: Under normal conditions, carbohydrates (4 kcal/gram) and fats (9 kcal/gram) are the primary energy sources, sparing proteins for tissue repair. Proteins (4 kcal/gram) are used for energy only when carbohydrate and fat stores are depleted, as in starvation, making this the function typically handled by other macronutrients.

Choice B reason: Proteins are essential for immune function, forming antibodies and immune cells like lymphocytes. Unlike carbohydrates or fats, proteins directly support this role, contributing 10-15% of dietary protein to immune responses, making this a primary protein function, not typically handled by other macronutrients.

Choice C reason: Proteins, like albumin, maintain fluid and electrolyte balance by regulating oncotic pressure in blood plasma, preventing edema. This is a unique protein function, as carbohydrates and fats do not directly influence fluid dynamics, making this an incorrect choice for a function handled by other macronutrients.

Choice D reason: Proteins are critical for building and repairing tissues, providing amino acids for muscle, skin, and organ synthesis. This is a primary protein function, requiring 0.8-1.5 grams/kg daily, not typically performed by carbohydrates or fats, which lack amino acids, making this an incorrect choice.