Final answer:
Epinephrine initiates lipolysis in fat cells when energy intake is restricted, leading to the breakdown of triglycerides into glycerol and free fatty acids which can then be used for energy.
Step-by-step explanation:
When energy intake is restricted, the neurochemical that initiates lipolysis in fat cells is epinephrine (option c). Lipolysis is the process by which triglycerides in fat cells are broken down into glycerol and free fatty acids under the influence of certain hormones. Epinephrine, along with other hormones such as glucagon and growth hormone, activates hormone-sensitive lipase, which is responsible for liberating fatty acids from fat cells. Insulin, on the other hand, inhibits this process and promotes storage of energy as fat.
The free fatty acids released during lipolysis are then available to be used by the body as an alternative energy source when glucose is in short supply. Additionally, the glycerol released can be utilized by the liver and kidneys to synthesize glucose through the process of gluconeogenesis, thereby supporting energy needs in times of restricted carbohydrate intake.