Metabolism after 40 — everything After Forty Feel has written.
The metabolic shift in your 40s and 50s has multiple drivers — cortisol, sleep architecture, hormones, insulin sensitivity, muscle loss. We've written about each layer. Start with whichever entry point matches what you're noticing.
If you've gained weight differently than before
The cortisol-belly research — what actually shifts at 50
"Stress is making you fat" is half-right and useless. The visceral-fat sensitivity shift in midlife is well-documented. Cortisol, declining estrogen, and sleep architecture combine to produce a measurable change in WHERE weight lands. What the Pontzer 2024 metabolism papers reframed.
If you're considering or curious about GLP-1s
GLP-1s for women 40-60 — the honest field guide
Semaglutide, tirzepatide, and the questions women in their 40s and 50s actually need answered: who benefits, who shouldn't take it, the muscle-loss problem nobody's talking about, the HRT interaction, and the regain curve.
The bloodwork that actually matters
Reading your bloodwork at 50 — what to ask for
The 8 markers that actually tell you about your metabolic trajectory: HbA1c, fasting insulin (not just fasting glucose), ApoB (not just LDL), TSH+T3+T4, vitamin D, ferritin, RDW, and the hormone panel. With reference ranges and what abnormal looks like.
Sleep, cortisol, and the metabolic feedback loop
Magnesium for sleep at 50 — form matters more than dose
Magnesium glycinate vs threonate vs citrate vs oxide. The form determines whether you absorb it and whether it crosses the blood-brain barrier. What actually works for the midlife sleep + cortisol + visceral-fat loop.
Why your sleep architecture changed at 47
The Walker lab research on slow-wave sleep shifts in late 40s. Sleep stage durations literally change shape, independent of cortisol or mood. What this means for metabolic recovery and the interventions that actually move it.
The hormone layer underneath everything
HRT after the 2024 reanalyses
Estrogen is a metabolic regulator, not just a reproductive hormone. The 2023-2024 WHI reanalyses updated the math for women in early menopause. How HRT affects insulin sensitivity, visceral fat distribution, and the metabolic trajectory.
Hormonal birth control in perimenopause — the bridge
The under-discussed treatment between perimenopause and full menopause. How low-dose hormonal contraception stabilizes the hormonal whipsaw that drives metabolic + sleep + mood disruption in the transition years.
The pathway approach
Metabolism pathway — start to clinician-ready
The full pathway from "something shifted and I don't know what" to "I have an evidence-backed plan I can discuss with my prescriber." Includes a bloodwork checklist, a movement framework, a sleep stack, and a hormonal-consideration decision tree.
TRT for men 40-60 — the actual decision framework
For the men reading along (or partners of women on this site): the testosterone conversation, who benefits, who doesn't, and the difference between TRT and a peptide stack.
The Sunday letter
Free. Research-led. One thoughtful letter a week.