Image from Bernd Helfert
The average person wastes at least an hour daily just on ruminating! Bored with munching your muesli? Become a Fastman!   — From "Galaxy On A Holiday", Wega Press 36789 L.T.
Thousands of years ago, with the advances of gengineering and nanotechnology, it became optional for a human or near-human to eat at all. A matter of taste, so to say. :-) Fastmen obtain all their energy and organic compounds through the nano inside their bodies.
Since pre-singularity times, humanity has dreamt of not needing to eat and happy life without shoving lots of dead organics into their mouths. Unfortunately, living off sunlight is impossible. No matter how sophisticated the technology or the biomods or gengineering, the human body surface is so small that sunlight falling onto it simply will not carry enough energy for living. Greenists of ancient pre-nanoswarm times bypassed this by utilising greenhouse-type biospheres. Another option is to have a patch on your skin adapted for absorbing hard radiation, like the well known nuke tattoo.
But forget about those niche maniacs! Modern fastman lifestyle is healthy, attractive and practical! Nano in the fastman body absorbs inorganic compounds from the air and atmospheric dust. Oxygen, water vapor, carbon dioxide and nitrogen are all turned into organic compounds and built into the body. The person needs only to eat a limited number of trace minerals, and, in cases of dehydration, some water.
As a fastman you, naturally, can eat if you want: for pleasure, in social gatherings and so on. However, a warning - a happy nearbaseline who lived long without any food can experience a sudden sensation when eir stomach receives first load in months. I once had a romantic dinner nearly ruined when my system reacted unexpectedly to simple atlantis crunchies. Thankfully, sophisticated nano solved the problem almost as soon as it appeared.
Necessary energy can be obtained by many means. Transporter nano supplies energy to all nano within a person's body. A common method is to have an energy-exchanging unit built into a surface which you touch frequently - clothing, bed, furniture, computer console etc. Fastman Shoes are a popular example, worn even by non-fastmen. Another arrangement is to have an ultratech miniaturised fusion reactor using a fraction of the air you breathe. Energy is obtained from fusing atoms of the light elements in the air. The final product, produced at the end of a chain of fusion reactions, are iron atoms, which are expelled from the body. Because each reaction in this chain gives less return of energy than the one before it, most fusion chains are for the sake of efficiency cut off early. However radical Fastmen prefer to extract every last erg. This has given origin to a popular exclamation "you rustshitter!", which means about the same as the old early interplanetary "you lucky bastard"!
For those with access to transapientech, and/or who are very affluent, more sophisticated technologies are possible. These include using conversion technology to convert matter to energy and generate a stream of energy-loaded molecules for a person's body.
As you might already have guessed, fastmen are frequently wealthy, trendy, interesting persons. Fed up with eating? Compassionate about poor food organisms? Then why not become a fastman yourself!