I literally cannot eat more than 500 calories a day - is this okay??

This one has a reasonably settled answer, so here it is. The RDA is the wrong reference and it is worth understanding why. 0.8 g/kg is the intake at which nitrogen balance is not negative in healthy weight-stable adults — a floor for deficiency prevention, not an optimum, and derived in a population that is not in a deficit. In a substantial energy deficit, protein requirement rises because amino acids are being oxidised for energy and because muscle protein synthesis is blunted. The literature on preserving lean mass during weight loss lands around 1.4 to 2.0 g/kg of reference body weight, which is roughly two to two and a half times the RDA.

NurseKim_ATL said:

The RDA is the wrong reference and it is worth understanding why.

True, and anyone with reduced kidney function needs that target set by a clinician rather than a forum. High protein is safe in normal kidneys and is not automatically safe in impaired ones.

nick_newbie said:

I tracked honestly for two weeks and averaged 68g of protein against a target of about 120g.

Can confirm the pattern nick_newbie describes. Distribution matters less than total but it is not nothing. Roughly 25 to 40g per sitting with enough leucine to trigger synthesis, three or four times a day, is more effective than the same total in one enormous evening meal — and on a suppressed appetite the enormous evening meal is the one you will not finish anyway.

Ask again with the specifics and you will get a better answer than this one.

Clinical perspective, offered as context rather than as advice.

DEXA scan update relevant to protein intake:

Scanned at months 0, 6, and 12. Here are the body comp numbers:

Lean mass preserved — actually GAINED 1-2 lbs thanks to progressive overload + 1.5g/kg protein. The protein intake discussion needs to include body comp data, not just scale weight.