Protein is necessary for

1. Tissue Repair and Muscle Mass:
   Essential for the growth and repair of tissues, including muscle. In malnourished patients, muscle wasting is a common problem 
2. Immune Function: 
   Involved in the production of antibodies and immune cells
3. Enzymes and Hormones: 
   Synthesis of enzymes and hormones that regulate various body functions
4. Fluid Balance:
   Protein, especially albumin, plays a key role in maintaining fluid balance in the body. Low protein levels can lead to edema (fluid accumulation), often seen in severe malnutrition.

In cases of protein-energy malnutrition (PEM), protein reserves are depleted, leading to muscle wasting, weakened immune response, and impaired organ function. An evaluation of the patient's protein requirements factoring in the severity of malnutrition and the presence of functional issues (such as swallowing and chewing difficulty), comorbidities (such as infection and/or cancer) and injury is necessary to determine the patient's unique metabolic demands.

The recommended dietary allowance (RDA) for protein in healthy adults is typically 0.8 grams per kilogram of body weight per day. However, for malnourished patients, this requirement is higher to compensate for increased metabolic demands and to promote tissue repair and growth. Note that protein quality is crucial; high biological value (HBV) proteins, which contain all essential amino acids, are preferred, but may not be affordable or available.

Ultimately, the goal of dietary intervention in PEM is to provide a balanced nutrition plan that not only rectifies protein deficits but also addresses overall energy, vitamin, and mineral requirements. 

When assessing a patient with Protein-Energy Malnutrition (PEM), a dietitian engages in a comprehensive and methodical thought process which addresses:

1. Analysis of Dietary Intake: Understanding the patient's usual dietary intake is crucial. The dietitian reviews the patient's current and past food consumption, focusing on protein sources. They assess the quantity and quality of protein intake, considering factors like the balance of essential amino acids and the presence of high biological value (HBV) proteins.

2. Anthropometry: Body mass index (BMI), mid-upper arm circumference (MUAC), weight history,

3. Biochemical markers: e.g. serum pre-albumin levels 

4. Nutrition-focused Physical Findings: Evaluation of the patient's overall nutritional status, looking for signs of malnutrition such as muscle wasting, edema (especially in cases of kwashiorkor), poor wound healing, and hair and skin changes. An Assessment of Gastrointestinal Function is important: The dietitian considers the patient's ability to digest and absorb nutrients. Issues like diarrhea, malabsorption, or reduced appetite are determined.

5. Identifying Micronutrient Deficiencies: Malnutrition often coexists with deficiencies in vitamins and minerals, which are vital for metabolic processes and immune function. The dietitian looks for physical signs of these deficiencies 

The goal is to develop a tailored nutrition care plan with emphasis on, 

1. Protein Requirements: The dietitian calculates the patient's protein needs based on their current health status, activity level, and the severity of malnutrition. This calculation often exceeds the standard RDA for protein (0.8 g/kg body weight/day for healthy adults) due to increased metabolic demands for healing and recovery.

2. Energy Requirements: Alongside protein, energy (calorie) needs are evaluated. In PEM, providing adequate calories is essential to spare protein for tissue synthesis rather than energy production.

3. Micronutrient Requirements