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Summary
On episode 385 of 40+ Fitness, Coach Allan sits down with Dr. Marc Bubbs, a naturopathic doctor who has worked with elite athletes across major sporting leagues for more than two decades, and the author of Peak: The New Science of Athletic Performance That is Revolutionizing Sports.
Dr. Bubbs introduces the blood glucose dysfunction spectrum, explaining why “normal” lab reference ranges often reflect an already unhealthy population, and links elevated fasting blood glucose to higher heart disease risk and depression risk, even below the diabetic threshold.
The conversation covers individual carbohydrate tolerance, using ketosis and intermittent fasting strategically for performance and fat loss, and why sleep and simple daily movement matter as much as anything you do in the gym.
Links
- https://drbubbs.com
- Episode 497 – How to reach your peak after 40 with Dr. Marc Bubbs
Key Takeaways
- “Normal” lab ranges often reflect a sick population, not an optimal one. A fasting blood glucose around 100 mg/dL might get a doctor's approval, but Dr. Bubbs recommends aiming closer to 80, since the reference range includes a lot of already unhealthy people.
- The blood glucose dysfunction spectrum runs from healthy to prediabetic to diabetic, not a hard on/off switch. Even within the “normal” range, fasting glucose in the upper end (100 to 125 mg/dL) is a yellow flag worth addressing through diet, exercise, sleep, and stress before it progresses.
- Ultra-processed food consumption tracks closely with obesity rates across countries. The US and UK spend over 50 percent of food budgets on packaged, boxed food, versus roughly 10 to 20 percent in Spain, France, Italy, and Portugal, a gap that lines up with obesity trends.
- Elevated fasting blood glucose is linked to higher heart disease risk, even below the diabetic threshold. A 22-year study found people in the top quartile of “normal” glucose (over 85 mg/dL) had about 40 percent higher cardiovascular risk than those at the low end, with the strongest link found in 40 to 49 year olds.
- Blood sugar and mood are directly connected. Higher HbA1c (a three-month average of blood glucose) and higher fasting insulin both correlate with increased risk of depression, and insulin-resistant individuals are three times more likely to struggle with depression, independent of medication.
- Carbohydrate tolerance is individual, driven partly by your gut microbiome. Continuous glucose monitor studies found some people spike on a banana the way others spike on a cookie, so there's no universal carb number; it depends on activity level, goals, and personal response.
- Time-restricted eating (intermittent fasting) works mainly by shrinking your total eating window. Cutting from an 18-hour eating day down to a 12-hour or 8-hour window naturally reduces calorie intake and, per Dr. Satchin Panda's research, improves markers like blood pressure, oxidative stress, and cravings.
- Sleep is a foundational, often overlooked performance and health lever. The average person sleeps just 6.5 hours, and once sleep drops below 6, blood glucose control, mood, and recovery markers noticeably worsen, a factor Roger Federer reportedly used to extend his career.
- Dr. Bubbs's three strategies to get and stay well: eat real, minimally processed food within a 12-hour eating window; prioritize 7 to 9 hours of sleep, aiming for about 8; and build daily non-exercise movement, like walking and stairs, on top of formal workouts.
“Compliance is the best predictor of how well you're going to do on a diet.”
Dr. Marc Bubbs