Final answer:
The CHO and N sparing effects of FFAs are that they conserve carbohydrates and protein nitrogen by causing tissues to switch from using glucose to fatty acids for energy, particularly when glucose is limited, as in fasting.
Step-by-step explanation:
The CHO and N sparing effects of FFAs refer to how free fatty acids help conserve carbohydrates (CHO) and protein nitrogen (N) during energy metabolism. In the presence of FFAs, tissues that have the ability to utilize fatty acids as an energy source switch from using glucose to using fatty acids. This process is driven by the hormone growth hormone (GH), which stimulates lipolysis, leading to the release of fatty acids from adipose tissue into the bloodstream.
The glucose-sparing effect occurs as these tissues now rely on fatty acids, resulting in reduced glucose uptake from the blood ultimately conserving glucose stores. During conditions like fasting or starvation, when glucose is scarce, the body enters into a state where the free fatty acids are not re-esterified due to the lack of 3-phosphoglycerate from glycolysis, an intermediate needed for this process. Instead FFAs are transported via the FFA-albumin complex to various organs for energy production. This process is part of the 'glucose-fatty acid cycle' which describes the relationship between the availability of glucose and the metabolism of FFAs. When the individual is well-fed and glucose is readily available, it leads to re-esterification of the FFAs halting their supply to the organs. This cycle indicates how energy substrate preference shifts between carbs and fats based on the body's dietary status.