What is a major consequence of under-consuming protein?

Under-consuming protein can lead to significant consequences for the body, primarily manifesting as muscle loss and decreased immune function. Protein plays a crucial role in the maintenance and repair of body tissues, especially muscle. When the body does not receive sufficient protein, it begins to break down muscle tissue to meet its needs for amino acids, which can lead to muscle wasting. This is particularly concerning for individuals engaged in regular physical activity or those who are older, as they may already be at risk for muscle loss.

Additionally, proteins are integral to the immune system; they are essential for producing antibodies and other immune responses. A deficiency in protein can weaken the immune system, making the body more susceptible to infections and illnesses.

In contrast, the other answer choices do not accurately reflect the consequences of inadequate protein intake. Increased energy levels and mental alertness are more likely to be associated with proper levels of carbohydrate and fat intake, rather than being direct advantages of protein consumption. Enhanced recovery from exercise typically correlates with adequate protein intake, not with under-consumption, as proteins aid in repairing and building muscle post-exercise.