I literally cannot eat more than 500 calories a day - is this okay?? — anyone have experience?

BiostatsBrad said:

Distribution matters less than total but it is not nothing.

BiostatsBrad has the substance of this right. The condition it depends on is worth stating. On a suppressed appetite the winning strategy is protein density per unit of volume, not per calorie. Isolate powders, Greek yoghurt and cottage cheese, egg whites, lean fish, and tinned tuna all deliver a lot of protein in a small physical volume. Front-load it: appetite is usually least suppressed in the first hours after waking and worst on the day or two after dosing, so get the majority in early in the day and early in the week.

BiostatsBrad said:

Distribution matters less than total but it is not nothing.

I will push back on the powder-first advice. It works and it also trains people out of eating food, and when the drug stops the habits are what remain. Getting protein from meals is slower and holds up better afterwards.

Taking the question as asked, rather than the general version of it. 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.

CarlaRPh_TPA said:

On a suppressed appetite the winning strategy is protein density per unit of volume, not per calorie.

Second this. The detail I would add is minor and it is already implied above.