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ForumsCOA & Analytical TestingAmino acid analysis for peptide identity — looking for input

Amino acid analysis for peptide identity — looking for input

MeganSA_TX Sun, Oct 12, 2025 at 6:34 PM 16 replies 1,337 viewsPage 1 of 4
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MeganSA_TX
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Oct 12, 2025 at 6:34 PM#1

My appetite is suppressed enough that hitting a protein target is now the hardest part of the day, and everything I read assumes I can simply eat more.

What I am trying to establish is whether the RDA is the wrong reference entirely during rapid weight loss, and what the actual target should be.

Not looking for reassurance. Looking for the part I have got wrong.

42 12PharmD_Rodriguez, julia.endo, JessicaM_2024 and 39 others
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HPLC_Greg
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Oct 12, 2025 at 8:57 PM#2

This one has a reasonably settled answer, so here it is. 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.

Last edited: Oct 13, 2025 at 2:57 AM
41 11JenPlateau, SallyK_inj, CryptoCarl and 38 others
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MarkLI_maint
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Oct 12, 2025 at 11:20 PM#3
HPLC_Greg said:
On a suppressed appetite the winning strategy is protein density per unit of volume, not per calorie.

Agreed on the target, with the caveat that reference weight and current weight are different numbers. Using current weight at the start of a large loss produces a target that is both unachievable and unnecessary.

40 10HPLC_Greg, LibrarianMeg, bri_stats and 37 others
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marcus_mpls
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Oct 13, 2025 at 1:43 AM#4
MeganSA_TX said:
My appetite is suppressed enough that hitting a protein target is now the hardest part of the day, and everything I read assumes I can simply eat…

Same position here, arrived at the long way round. 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.

Correct me if the detail matters more than I have assumed.

39 9Dr.PathRoch, mona_PHX, andrew_nyc and 36 others
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Dr.SurgeonPGH
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Oct 13, 2025 at 3:59 PM#5

From the other side of the consultation, briefly.

DEXA scan update relevant to protein intake:

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

BaselineMonth 6Month 12
Total mass275 lbs235 lbs212 lbs
Fat mass115 lbs75 lbs47 lbs
Lean mass153 lbs146 lbs149 lbs
Body fat %44%32%21%

Lean mass preserved — actually GAINED 1-2 lbs thanks to progressive overload + 1.6g/kg protein. The protein intake discussion needs to include body comp data, not just scale weight.

Last edited: Oct 13, 2025 at 6:59 PM
38 8B12Beth, RickReta_CO, PharmHunterJen and 35 others
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