There are, however, some foods where the caloric expenditure to process them is a little higher than the calories they provide the system. The clear example is water, especially ice-cold water. The body needs to warm it up before absorbing it, leading to a small caloric debt. Foods with very high water content, such as celery, also have this tiny catabolic effect. But the nutritional value of water and celery are not high enough to properly sustain an organism, so relying solely on these foods to lose weight can lead to serious health complications.
Proteins are composed of carbon, hydrogen, oxygen, and nitrogen arranged in a variety of ways to form a large combination of amino acids . Unlike fat the body has no storage deposits of protein. All of it is contained in the body as important parts of tissues, blood hormones, and enzymes. The structural components of the body that contain these amino acids are continually undergoing a process of breakdown and replacement. The respiratory quotient for protein metabolism can be demonstrated by the chemical equation for oxidation of albumin: