Sandstead Performance and Nutrition

Licensed Cycling Coach and Certified Nutritionist. Helping clients of all abilities nail their goals.

[Iñigo San Millán @doctorinigo]

The airplanes that never returned....
Abraham Wald’s lesson was not just about airplanes.
It was about science.

During World War II, the military studied the planes that returned from combat, covered in bullet holes. The obvious conclusion was to reinforce the damaged areas.

But Wald understood the deeper truth:
Those planes had survived...The real answer was in the planes that never returned.

This is where many of the biggest advances in medicine and science are hiding today.

Not in the data we already measure. Not in the incremental questions protected by conservative medical schools, funding mechanisms and established dogma.
But in the missing signals.
The patients who do not respond.
The mechanisms we are not looking for.
The hypotheses that do not fit the dominant model.

The biological “airplanes” that never make it back into our datasets.

Incremental research is important. But paradigm shifts rarely come from polishing what we already see.

They come from asking:
What are we not measuring?
Who is missing from the data?
What mechanism has been invisible because our framework was wrong?

The future of medicine may depend less on reinforcing the bullet holes we can see, and more on understanding the airplanes that never returned.

[Iñigo San Millán @doctorinigo]

Empires have fallen, generations have passed and yet every evening whispers the same truth:

that endings are not the opposite of beginnings, but the path that leads to them.

Perhaps that is why sunsets have fascinated humanity since the beginning of time.

They remind us, gently, that mortality and continuity share the same horizon.

For every dawn is born from a sunset.

[Iñigo San Millán @doctorinigo]

Every few months, a new therapy arrives with the same promise: activate this pathway, inhibit that enzyme, filter your blood, flood your cells with light, and the clock of aging will slow.
NAD+ precursors, senolytics, mTOR inhibitors, plasmapheresis, ozone infusions, methylene blue…
The list grows longer, the marketing grows louder, and the evidence, the actual human evidence, stays stubbornly thin.

Walk into most longevity clinics today and the experience is carefully constructed. Red light panels. Cold plunges. IV drips. Expensive diagnostics. Physicians positioned as pioneers. It looks sophisticated. It feels scientific. It costs a great deal of money….

But here is the uncomfortable question nobody in this space wants to ask: are we actually improving human longevity, or are we stacking interventions on top of a poor understanding of human physiology?

https://t.co/SQfrCsilou

[Alan Couzens @Alan_Couzens]

Re yesterday's post...

I'm not anti GLP-1

I am anti a society in which the only way we can maintain a healthy weight is via appetite suppression.

Of whatever form... GLP-1... keto etc.

How far are we going to take this?

As technology *advances* even further, and we basically only expend our BMR every day, do we just keep dialing up the strength of these drugs so that we keep eating less and less?

Humans were built as physical organisms - to move, to act on the physical world, expending energy.

We certainly weren't made to live on <2,000 kcal/d.

[Tim Noakes @ProfTimNoakes]

The limiting factor in most is their blood insulin concentration which is regulated by the muscle glycogen concentrations. Get your insulin below 6 (units) and the fat oxidation takes off. But that requires a low muscle glycogen content which requires a.... (yes you guessed it).
https://t.co/hvMlV4MizI

[Alan Couzens @Alan_Couzens]

A question I get all the time:

"I have a busy life, and I only have a few hours to train each week. Shouldn't I make them count by going harder?"

No.

See, your body doesn't separate training stress from life stress.

If you're carrying a full-time job, poor sleep, family responsibilities, and financial stress, your "stress bank account" is already running too low for high-intensity training....

You're broke!

Your adaptation reserves are already being spent!

My latest...

Why Too Much Intensity Breaks Athletes:
Understanding Adaptation Energy

[Camus @newstart_2024]

A Swiss chemist tested meth derivatives on his wife while playing tennis.

When she got hyper-focused, he named the drug after her - Ritalin.

That’s how ADHD meds started.

Now 1 in 10 boys in America is on Adderall or similar.

There is no blood test, brain scan, or biological marker for ADHD. Diagnosis relies on subjective checklists and rating scales, often created or influenced by the companies that sell the medications. Boys are diagnosed at roughly twice the rate of girls.

I’m genuinely curious, do you think ADHD is over-diagnosed, especially in boys?

[Alan Couzens @Alan_Couzens]

When it comes to fat/carbs, we should learn from history...

1970's-80's: *All* athletes should eat high carb if they want to be successful.

1990's: Recreational endurance sport ("Fun runs" etc.) takes off. Lots of low-moderate volume athletes eating in the same way as high-volume athletes, leading to problems...

Late 90's - 2000's: A lot of these athletes start encountering health problems as they age - insulin resistance etc, e.g. Tim Noakes, Mark Sisson... and start to revise their approach.

Also late 90's - 2000's: Long distance races e.g. Ironman start to really become popular, and a lot of folks realize they're very metabolically limited when it comes to the long stuff, even very high-level athletes e.g. Mark Allen. This is also when I started metabolic testing of these athletes, and it 100% confirmed these impressions.

2010's: This is taken to extremes and very low carb/keto becomes somewhat popular among athletes, esp ultra athletes - Volek/Phinney paper comes out etc., Athletes start to realize the performance limits of this approach eventually leading to a swing back in the other direction.

2020's: Back to where we started - *All* athletes should eat high carb if they want to be successful.

[Iñigo San Millán @doctorinigo]

The CHO debate does not die in journals. It dies every day in real competition.

One thing that is often forgotten is that sports science frequently validates what practitioners have already been doing successfully in the field for years. The laboratory is essential, but it is not always where innovation begins.

~20 years ago, when I was recommending and using 80-100 g/h of carbohydrate with elite athletes, many in the Carb camp, considered it crazy, unrealistic and impossible... Yet it worked remarkably well in practice. The athletes did not care about the debate. They cared about performance.

~10years ago, I began using protocols approaching 125 g/h. This time I kept quiet. I knew it provided a significant competitive advantage and I had no interest in debating it publicly. In 2021, UAE and Tadej Pogačar helped demonstrate to the world what many of us had already seen firsthand: higher carbohydrate intakes could transform performance when implemented correctly.

Now, after more than a decade of practical application, these strategies are being presented as a major scientific breakthrough because they have finally appeared in the literature.

This is not an argument against science. Quite the opposite. Science is a process. It evolves. Even within the carbohydrate camp, recommendations have changed dramatically over the last two decades because the original understanding was incomplete.

The lesson is simple: evidence comes from both the laboratory and the battlefield. The best advances in sport happen when science and practice inform each other, not when one dismisses the other.

Sometimes the peloton is already living in the future while the journals are still trying to describe the past.

[Tim Noakes @ProfTimNoakes]

Thank goodness Gary Taubes @garytaubes chose physics over medicine and then came from there to science journalism. His latest book https://t.co/ptTIjfe3Di is another masterpiece. His ability to research the history of the medical topics that interest him and to present the material with novelty, accuracy and clarity in a most engaging way, is of the highest quality.
I learned two crucial facts from his deep dive into the historical evolution of the management of diabetes of both types.
First, when insulin was discovered in 1921, it produced an instant miracle cure by saving the lives of those who were unable to produce any insulin, those with type 1 diabetes. But the honeymoon period lasted just 15-20 years after which insulin-treated diabetics began to present with premature atherosclerosis.
By which time, the prevailing opinion had become that this was caused by a diet too high in fat. For the life-saving insulin had to be innocent - Remember Semmelweis and the doctor-caused disease that he decribed.
Thus the prescribed treatment for diabetics of both types became a low-fat high-carbohydrate diet, just as was being prescribed to cardiac patients to prevent disease progression.
Second, Taubes made the telling point, overlooked by many, that one of two diets is prescribed to prevent atherosclerosis in normal persons and in those with diabetes. There are the fat substitution diet and the low-fat diet - and they act quite different especially in persons with insulin-resistance or type 2 diabetes.
In the fat substitution diet, saturated fats are replaced with polyunsaturated fats. There have been numerous long-term multi-million $ trials of this dietary intervention. They have all failed miserably to show benefit and some have caused harm https://t.co/HPWJ8OZWJE.
Thus we know that the fat substitution diet is a complete failure and may even be harmful.
In the low-fat diet, a large portion of the fat in the diet is replaced with carbohydrate. Whilst this diet may be acceptable for those who are not insulin-resistant, for those who are diabetic, it has to be the worst possible choice. Because, with time as the patient becomes progressively more insulin resistant, he/she will require ever larger doses of insulin to maintain blood glucose concentrations in a reasonable range. And didn't the problem of atherosclerosis first appear in middle-aged type 1 diabetics who had been treated with insulin for some decades?
Importantly there has never been a major multi-million $ trial of the effects of a low-fat high-carbohydrate diet on the development of atherosclerosis in otherwise health individuals. But there has been one such trial on weight loss and cardiovascular outcomes in diabetic patients - The LookAhead trial. The study was terminated after 9.5 years because it was considered "futile" to continue as there was no evidence that the diet produced any protection from coronary heart disease.
The point is that if you have diabetes, you're probably not best advised to adopt either a fat-substitution diet or a low-fat high-carbohydrate diet, since neither is likely to produce any health benefits and both could be harmful.
@BenBikmanPhD @zoeharcombe @bigfatsurprise @AKoutnik @LoreofRunning1 @sweatscience @drericwestman @markkaplan20

[Alan Couzens @Alan_Couzens]

Doing sporadic hard things is easy.

Doing consistent easy things is hard.

[Mark Hyman, M.D. @drmarkhyman]

90 percent of chronic disease is determined not by our genome but by our exposome — everything that has happened to you over your lifetime washing over your genes.

[James DiNicolantonio @drjamesdinic]

What people think SALT does:
- Causes high blood pressure

What SALT actually does:
- Increases energy
- Strengthens bones
- Improves cognition
- Improves hydration
- Decreases headaches
- Reduces muscle cramps
- Decreases sugar cravings
- Improves athletic performance

[Alan Couzens @Alan_Couzens]

Why knowing your training zones is important 👇

Different zones drive different adaptations:

- Fat burning
- Cardiac remodeling
- Mitochondrial density
- Lactate clearance
- Neuromuscular power

While there is overlap, the relationship between volume and intensity required to maximize each adaptation is different.

For example, increasing the power at which max fat oxidation occurs requires a relatively high volume at a low intensity. Increasing neuromuscular power requires very high intensities, but can benefit from quite low volumes.

Without clear zones, most athletes drift into the middle - too hard to maximize the low-intensity adaptations, too easy to stimulate the high-end.

This is often the difference between "OK" and "great" athletes. You can become "OK" just by throwing a moderate amount of volume at a medium intensity at an athlete, but in the long-term, this "gray zone" training is ultimately limited...

The “gray zone” is where long-term progress goes to die!

Identifying and sticking to your zones allows you to:
• Match stimulus to desired adaptation
• Balance gain vs recovery cost
• Accumulate sustainable training load
• Periodize effectively over months & years

Most importantly, it helps ensure that easy days stay easy enough and hard days are hard enough.

Bottom line:

Intensity discipline is one of the defining traits of elite endurance programs!

[Iñigo San Millán @doctorinigo]

30 years ago I was working with elite athletes and drawing training zones on paper based on blood lactate curves.
No substrate data. No indirect calorimetry. Just the conviction that something metabolically distinct was happening at each intensity — and that Zone 2 was where the most important adaptation was taking place.

In 2005 I began adding fat and carbohydrate oxidation rates to the picture, and what the substrate data revealed confirmed what the lactate curves had been suggesting all along: each intensity represents a distinct metabolic state, not just a point on a continuum of effort.

That work became the Metabolic Map in 2013. Then the metabolic flexibility paper with George Brooks in 2018. And now the updated 2026 framework, which maps four metabolic states onto classical threshold models and asks a question the older models never quite posed:
Is the system in optimal metabolic balance, or is it drifting away from it?

Lactate turns out to be the best real-time proxy we have for answering that question. It tracks metabolic equilibrium, the onset of drift, and the progression toward overload better than any other single variable we can measure in the field.

Thirty years of work. One molecule. One central question.

My last substack article

https://t.co/hvNuIVnH6b

[Alan Couzens @Alan_Couzens]

The gap between endurance athletes and public health recommendations is one of truth...

We need to start treating adults like adults and giving them an honest appraisal of the sort of fitness 150min/wk leads to.... i.e. very very poor fitness.

If you want the truth, look to the folks from your local 10K or half-marathon training 2.5 hrs/wk...

Oh, that's right, there aren't any.

Even the overweight, out-of-shape, folks who are walking by mile 3 are *still* putting in more than 2.5 hours of training per week. And they're in horrible shape.

The lean, fit folks at the front of the event with the health and fitness that you seek... a lot more.

It's time to get real. It's time to get truthful. It's time to stop the coddling...

"I know you're too busy to actually exercise the amount you need to, so just try this amount instead."

We're grown-ups. We can accept the truth.

[Iñigo San Millán @doctorinigo]

My updated metabolic map is less focused on substrate utilization and thresholds and more focused on metabolic stability. I believe the shift is subtle but important.

Instead of only asking:
“What fuel is being used?”

The model also asks:
“How stable is the metabolic system under stress?”

In this framework, lactate becomes the central proxy to understand the balance, drift, or overload of the metabolic system.

Approximate translation and comparison with different models:

• Zone 1 = low metabolic stress
Clearly below LT1/VT1

• Zone 2 = metabolic equilibrium
Near LT1/VT1, where lactate production and clearance remain tightly matched and the system operates at its highest sustainable balance

• Zones 3–4 = metabolic drift
The system progressively moves away from optimal mitochondrial matching capacity, even if lactate may still achieve a “steady state”…CP/MLSS/VT2/LT2/V4…

• Zone 5+ = metabolic overload
Above CP/MLSS/VT2/LT2/V4, where no true steady state is physiologically achievable

The key conceptual distinction:

A lactate steady state is not the same as optimal metabolic equilibrium.

The metabolic equilibrium ceiling is near LT1/VT1 and Zone 2.

The steady-state ceiling is CP/MLSS/VT2/LT2/V4.

Performance is ultimately defined by how long the body can preserve metabolic equilibrium.

[Alan Couzens @Alan_Couzens]

The biggest lever isn't workout intensity.

It's building a life that makes consistency boringly easy.

Same routes. Same time of day. Same low ego pace.

Do that for a few years and "fitness hacks" start looking very silly.

[Camus @newstart_2024]

Rhonda Patrick just gave a super practical breakfast recommendation on Chris Williamson’s podcast.

She recommends eggs (4–5 depending on your size) scrambled, paired with bacon, steak, or smoked salmon for omega-3s. She prefers pasture-raised eggs because the chickens eat grass and greens, boosting choline (key for brain function) and lutein.

Simple, high-protein, nutrient-dense, and no processed junk.

Studies confirm egg yolk choline improves verbal memory and cognitive function, while pasture-raised eggs contain significantly more lutein, omega-3s, and better nutrient profiles than conventional ones. High-protein breakfasts also stabilize energy and focus throughout the day.

Most breakfast advice is either overly complicated or loaded with sugar. This feels sustainable and actually nourishing.

I’ve been leaning into higher-protein mornings lately and the difference in steady energy is noticeable. Rhonda’s approach feels refreshingly straightforward.

What’s your go-to high-protein breakfast that actually keeps you full and sharp?

[Alex Honnold @AlexHonnold]

This is an article that I wrote following the death of Dean Potter in 2015 that I think does a good job of highlighting how inspirational he was to me personally and showing how much I admired his approach to his arts. The recent @HBO show The Dark Wizard used some of my interview clips to really make our relationship seem hyper competitive and dysfunctional, but the reality was a little more prosaic - we didn’t know each other super well and rarely saw each other. I was always kind of afraid of him because he was so intense. But I’d always been super inspired by his climbing and his vision.

We overlapped in Yosemite to some extent from 2006 until his death in 2015, so that’s nearly a decade in which I was normally spending about 3 months a year in Yosemite. We each did a handful of climbs over that time that were considered “competitive” (the Nose speed record being an obvious example). When you see it all in a 4 episode documentary it seems super fast and extreme - when you actually live it over a decade it all feels a lot slower and more normal…

The Dark Wizard does an amazing job of remembering Dean as the visionary climber that he was and it’s certainly worth a watch. Just remember that it’s edited for maximum effect.

https://t.co/ZujUomWKcV