[syhprum (OP)]

If I expend energy to accelerate a body  to near c , have it loop around a BH and come back to be when it arrives back it has aged less than me.
Energy is meant to be conserved but the energy imparted to this body has dissipated in making it younger does the reverse apply does the simple passing of time lead to the creation of energy.

[jeffreyH]

The passage of time, on its own, does not result in energy. You can have rest energy, kinetic energy and potential energy. Time is always a component of energy. The time component is always part of a scalar quantity. This is either v² or c².
In considering time dilation, yes the energy evolves more slowly when viewed from a frame at rest with respect to it. Locally this is not true. So it can only be considered globally. Since no absolute frame exists it is impossible to view things globally.
The only objects that are likely to be travelling at relativistic velocities are individual particles or molecules. On a global scale this is a very small percentage of the mass of the universe. So it has a minimal effect on the overall amount of energy.
Even if time dilation slows down the evolution of energy in moving systems no energy is lost or destroyed. It is always conserved.

[yor_on]

Syphrum, you can't use that unless you invoke frames of reference for it. From your frame it has aged less than you, from its own frame its clock is invariant, with your clock (the universe) 'speeding' relative its own. You could ask yourself what energy is needed for a whole universe to shrink relative ones speed. If taken to infinity the energy needed is infinite to close in on the speed of light, but if we stay at relativistic speeds contracting a universe then the amount of energy you spent gaining that speed can't be anywhere close to the energy needed for contracting a whole universe.
=

Actually, as there is no golden standard for what the 'universal time' is, every observer defines his own clock to be one.
So trying to define time to different frames, is always 'frame dependent' looked at one way. But the way we define a repeatable experiment tells us another story, and in that story all clocks are equal. That's also what uniform motion tells us, both from the view of black box experiments proving all uniform motions to be inseparable, and from the possibility of doing a repeatable experiment no matter your relative 'speed'.

Sorry, was 'framed' wrong here.
But now the frames should be aligned, blame it on medicines :)
==

It's even weirder than that. Some people define lights speed in vacuum (as a constant) to be a result of time dilation and length contraction, relative what frame of reference you measure it in. On the other tentacle, the speed of light is a invariant result from any frame of reference (including ones speed f.ex) and it is as a result of this both time dilation's and LorentzFitzgerald contractions exist. That's also a good reason as to why SpaceTime is defined to have four dimensions.

Those 'dimensions' then adapting to mass and speeds is not a result of 'energy', at least not in the meaning of me spending a 'equal magnitude of energy' relative what contraction, as well as time dilation, you find before you at a relativistic speed. So in the meaning of all clocks being equal you can possibly see that as a result of how the universe adapts to your local SpaceTime position , but it also puts into question anyone telling you that there is 'slow time' and 'fast time'. Locally defined time (local clock) is a equivalent to 'c', as far as I get it.

[Bill S]

Energy is meant to be conserved but the energy imparted to this body has dissipated in making it younger.

In this instance, what does "dissipated" mean?  What has actually happened to the energy?

[Petrochemicals]

If you looped round a black hole even though you would be undergoing massive acceleration, the the gravity from the black hole would surely be having a notable effect on time, I have an inckling that the gravity required to do a 180 on matter will possibly offset the angular acceleration ? Given there will be the initial acceleration.

[yor_on]

Don't know if I put that strongly enough?

The reason why we talk about length contractions and time dilation's is due to 'c' existing in every frame of reference.
So the first conclusion in where you explain 'c' by those is wrong. Those are indeed needed to explain a 'global view' of the universe, but locally your clock defines your life expectancy, no matter where you are. That's 'c', and that's your local clock.