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.
Valves are used to develop a pressure differential (throttle valves), to prevent the reverse flow of a fluid (check valves), to release a certain amount of gas, vapor, or liquid when the pressure exceeds a set value (safety valves), to control pressure or flow rate (regulating valves), and to reduce pressure and keep it at a constant level (reducing valves).