Why three receptors matters — GCG arm for lipolysis, not just weight
205 posts
People talk about reta as 'tirze plus.' It's not. The glucagon receptor agonism does something tirze literally cannot do — direct lipolysis and increased resting energy expenditure.
Mechanism in brief: GCG receptor activation on adipocytes upregulates HSL and ATGL → releases FFAs → hepatic oxidation. Plus increased thyroid conversion (T4→T3) peripherally. That's why reta runs you warmer and why fat loss composition may differ from pure GLP-1 class.
Practical implications:
- Muscle sparing may be better than tirze on high-protein intake because the energy deficit is partially pulled from fat oxidation rather than purely from appetite suppression.
- Thermogenic response means expect slightly higher kcal baseline — you can eat more and still lose.
- HR/BP bump isn't a bug, it's sympathetic activation from GCG. Watch it.
Curious what others' DEXA data says on LBM retention. This is the claim that needs testing.
- CJC-1295 no DAC · 100 mcg · pre-bed · sub-Q
- Ipamorelin · 200 mcg · pre-bed · sub-Q
- BPC-157 · 500 mcg · 2x/day · sub-Q
10 Replies
31 posts
Protein intake across both cycles? LBM retention is downstream of protein + training volume more than compound choice. If your protein was lower on tirze it skews the comparison.
45 posts
I have DEXA at 0/8/16 on both tirze (last year) and reta (ongoing, through week 12 so far). Tirze: lost 22lb, ~3.5lb LBM. Reta: lost 18lb through week 12, 1.8lb LBM. Too early to call but the trend matches what you'd predict from GCG-driven fat oxidation.
115 posts
The GCG → lipolysis mechanism is solid in rodent and ex vivo data. Human in vivo contribution at therapeutic reta doses is less characterized — some of the thermogenic effect people feel may be central (hypothalamic) rather than peripheral lipolysis. Mechanism is plausible but 'how much' is the open question.
45 posts
@macrosguru same macros (2g/kg protein), same training (4x/week upper/lower), same sleep tracking. Not RCT-clean but as controlled as a self-experiment gets.
26 posts
The thermogenic subjective thing is real — I said it in another thread, I literally sweat more on reta. Sympathetic activation is the most parsimonious explanation.
39 posts
The 'muscle sparing may be better' claim needs a lot more n. @dexa_devotee's data is encouraging but one subject. Anyone else with paired DEXA across classes?
37 posts
I'll have paired data in ~8 weeks. Finishing tirze DEXA now, starting reta February. Same training, same macros. Will post.
205 posts
@citation_required fair, I softened it too little. The thyroid angle is hypothesis not established. Peripheral oxidation bump is the durable claim.
- CJC-1295 no DAC · 100 mcg · pre-bed · sub-Q
- Ipamorelin · 200 mcg · pre-bed · sub-Q
- BPC-157 · 500 mcg · 2x/day · sub-Q
71 posts
The T4→T3 conversion bump claim is softer than the lipolysis one. Some signals but human data is thin. Don't want readers walking away thinking reta is a thyroid modulator — that's overreach.