Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Does diet coke break a fast? What the science actually says

Nov 29, 2025 · 14 min read

Diet Coke typically does not break a strict, calorie‑based fast because it contains about 0–5 calories per serving. But its non‑nutritive sweeteners can still activate sweet‑taste receptors and the gut–brain axis, potentially nudging insulin, gut hormones, and hunger—and quietly dulling some fasting benefits in certain people. “From a pure calorie standpoint, diet soda does not ...

Normal range vs optimal: What labs actually mean for men

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Nov 29, 2025 · 13 min read

Many men are told their blood work is “normal” even though they feel tired, softer, and off their game. Understanding optimal vs normal lab ranges can turn a frustrating dead end into a clear plan to feel and perform better. “When a lab report says ‘normal’, it mostly means you’re not in immediate danger. It ...

Nad+ side effects: What science really says about safety, injections, and anti-aging hype

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Nov 29, 2025 · 13 min read

NAD+ is a coenzyme that helps cells make energy and repair damage, but NAD+ injections are still an experimental longevity therapy with limited high-quality human data, so long-term safety, side effects, and anti-aging benefits aren’t established. Here’s what the evidence actually shows so far—and what to weigh before paying for NAD shots. “NAD+ is central ...

Is Propel water healthy or just clever marketing?

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Nov 28, 2025 · 9 min read

Propel is generally healthier than sugar-sweetened sports drinks because it has 0 g added sugar, avoiding the 30+ g glucose load a typical 20‑oz sports drink can deliver—enough to nearly hit the American Heart Association’s daily added-sugar limit and drive insulin spikes. The catch is that its sweetness comes from additives like sucralose, so the ...

Are Clif Bars healthy or just clever marketing?

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Nov 27, 2025 · 10 min read

For most sedentary people, a Clif Bar isn’t a “healthy” snack—it’s often a ~250‑calorie, ~20‑gram sugar glucose load that can spike insulin and blunt lipolysis (fat burning). Here’s how to read the ingredient matrix and know when a bar is functional fuel versus candy with a halo. “Most patients treat protein bars as a free ...