Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Essential biomarkers runners should track to run faster and avoid injury

Dec 04, 2025 · 14 min read

Key biomarkers runners should track include iron status (ferritin, hemoglobin), vitamin D, key hormones (cortisol, testosterone), blood-sugar markers, and inflammation/recovery signals — and many clinicians flag ferritin below about 30–35 ng/mL as a red flag for depleted iron stores that can reduce oxygen delivery and performance. Here’s how to interpret the numbers, spot problems before ...

FDA peptide regulations: What’s actually legal today

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Dec 03, 2025 · 9 min read

Peptides are legal in the U.S. only when they’re FDA‑approved drugs or can be compounded under Section 503A—however, the FDA’s “Category 2” list now includes 17 peptides (including BPC‑157) that pharmacies can no longer legally compound for human use. If you’re searching “FDA peptide regulation news today,” this Category 2 shift is the headline change ...

Do runners live longer? The science behind mileage and mortality

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Dec 03, 2025 · 15 min read

In long-term studies, running as little as 5–10 minutes a day at an easy pace is linked to roughly a 3-year longer lifespan and about a 27% lower risk of all-cause mortality versus not running. The sweet spot for longevity appears to be moderate weekly volume (around 2–3 hours), not marathon-level mileage—here’s how it works ...

Is your diet sabotaging your hormones? The science of testosterone killing foods

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Dec 03, 2025 · 16 min read

Testosterone typically declines about 1% per year after age 35, but a “Western” diet high in ultra-processed fried foods, sugar-sweetened drinks, and refined grains is linked to even lower levels by driving chronic inflammation, belly fat, and insulin resistance. Here’s what the research says to limit, what to watch for, and how to build meals ...

Volume eating: How to lose weight by eating more food, not less

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Dec 02, 2025 · 12 min read

Volume eating can help you lose weight by centering meals on low–energy density foods (fewer calories per gram), letting you eat a similar volume, trigger fullness signals, and still reduce total calorie intake. Here’s how to use big, fiber- and water-rich portions without shortchanging protein, healthy fats, energy, or your relationship with food. “Volume eating ...