Will using a resistor in series with a LED to control its voltage increase the total energy expenditure?
You've got the right idea.  Partly.

An LED used with a series resistor does waste the energy dissipated in the resistor.  Depending on the voltage from the power supply, you can easily waste more energy in the resistor than you use for the LED.

So far, you are correct.

What I want to correct is the idea that the resistor is there to lower the voltage.

The resistor is there to limit the current.

LEDs are current driven devices.  The forward voltage varies with current and temperature.

To get a stable brightness out of an LED, you regulate the current.

You will have noticed that the calculation for the series resistor uses the desired LED current.  You take the difference of the supply voltage and the (approximate) forward voltage of the LED, and divide that by the current to find the value for the series resistor.

If you tried to regulate an LED only by regulating the voltage, then you would destroy your LED very quickly.  Just below the forward voltage, the LED doesn't light up at all. Just above the forward voltage the LED becomes the next best thing to a short circuit.  There is a tiny range in between where it lights up and passes only a little bit of current.

That little range is impossible to hit with just a voltage regulator - it moves with temperature and current - current makes the LED get warmer, and warmer makes the LED conduct more.  You would be varying the voltage up and down wildly with some kind of feedback circuit measuring the current.

Or, just regulate the current to begin with.  Provide no more current than needed to light your LED at the desired brightness, and let the voltage do as it pleases - the voltage is of no interest.