Return to running after weight loss — January 2024

DanielChem_CHI said:

The honest range is roughly 20 to 40% of total loss as lean mass without deliberate resistance training, and roughly 10 to 20% with it plus adequate…

Pushing back on DanielChem_CHI here. I think this board over-worries about lean mass. Some lean loss is obligatory — you need less muscle to move a smaller body, and preserving mass you no longer need is not a health outcome. The question is whether strength and function held, and mine did.

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

tyler_CSCS said:

I lifted three times a week throughout and still lost lean mass.

Muscle fiber type changes during GLP-1-mediated weight loss, relevant to lean mass: preliminary biopsy data suggests that weight loss shifts the skeletal muscle fiber type distribution:

• Decreased Type IIx (glycolytic, fast-twitch) fibers
• Increased Type I (oxidative, slow-twitch) fibers
• Improved mitochondrial density and function
• Enhanced insulin-stimulated glucose uptake per fiber

This "metabolic remodeling" of muscle may contribute to improved insulin sensitivity independent of total lean mass changes. The muscle you keep becomes metabolically better, even if there's less of it[1].

CarlaRPh_TPA said:

I think this board over-worries about lean mass.

Bone density monitoring on lean mass: DEXA bone density at baseline and month 12.

Lumbar spine T-score: -0.10 → -0.8 (stable to slightly improved)
Femoral neck T-score: -0.11 → -0.9 (stable)

No significant bone loss despite 52 lbs of weight loss. Key factors: adequate calcium (1200mg/day), vitamin D (5000 IU/day), resistance training 3x/week, and adequate protein. Weight-bearing exercise is critical for maintaining bone density during rapid weight loss.

A narrower follow-up, since the general answer is now clear:

Whether resistance training and protein change the ratio or only the absolute amount?

Reporting back.

Second scan under matched conditions came back with the lean number nearly a kilogram higher than the first, so a chunk of what I panicked about was hydration. Strength numbers were up throughout.