The main issue is body composition (see the body fat calculator for more). Calorie expenditure will vary depending on the ratio of body fat to muscle or lean mass. NOTE that as our bodies adapt to exercise and our body composition changes - so will the amount of Calories burned.
The definition of a throttle is a valve that controls the fluid flow. An example of a throttle is a car part that controls how fuel moves through the system. Throttle is defined as to control the speed of an engine or the flow of fuel in an engine, or to hold down or choke.
The amount of air in the engine is controlled by the air intake system. A throttle body is part of the air intake system that helps control the amount of air that gets into the engine. If the throttle body fails, the engine will not get the proper mixture of air and fuel and the engine may lose power.