American Board of Surgery Qualifying Exam (ABS QE) Practice Test

How many calories per gram are provided by protein?

1. 4 calories

2. 9 calories

3. 7 calories

4. 6 calories

The correct answer is: 4 calories

Protein provides approximately 4 calories per gram. This value is established through metabolic studies that measure how macronutrients are utilized in the body. Proteins are made up of amino acids, which are the building blocks of tissues and play vital roles in numerous biological processes. During metabolism, the body utilizes proteins for energy production, and the caloric value reflects the energy released from breaking down protein. The other options indicate caloric values associated with different macronutrients. For instance, fats provide about 9 calories per gram, making them a more energy-dense nutrient, while carbohydrates also provide around 4 calories per gram, similar to protein. The values of 6 and 7 calories do not correspond to any of the recognized macronutrients' caloric contributions and thus can be ruled out when considering standard nutritional guidelines.