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Today’s Health Upgrade

• Controversy in longevity

• It’s time to rethink your fiber goal

• Use it or lose it: the anabolic window

In The News
The Longevity Test That Might Be Telling You Nothing

For years, the pitch has gone something like this: your NAD+ is declining with age, your cells are running low, and the fix is either a supplement or a blood test to track it. A newly published study just complicated that story considerably.

Scientists found that NAD+ levels in your blood do not decline with age, which challenges the idea that supplements targeting NAD+ improve longevity.

Scientists measured whole-blood NAD+ concentrations across roughly participants in seven independent groups — some comparing younger adults to older ones, others putting participants through exercise programs, dietary interventions, or combined lifestyle changes. 

They found no meaningful decline with age and no meaningful response to exercise, diet, or multimodal lifestyle interventions. In every case, blood NAD+ stayed the same. 

The only thing that changed it was an NR supplement, and researchers added that on purpose, just to make sure their measuring tool actually worked.

The deeper issue is whether NAD+ actually declines with age in healthy people at all. Much of that belief wasn't built on direct human evidence. It came from animal studies and review articles summarizing other researchers' work. 

The data increasingly suggest that NAD+ in otherwise healthy adults may be far more stable over a lifetime than the narrative implies. Where it does appear to come under real pressure is in specific conditions of metabolic stress: heart failure, certain neurological diseases, and severe alcohol dependence. That's a very different claim than "aging depletes your NAD+ and you need to replace it."

None of this means NAD+ biology is irrelevant. NR supplementation has real, peer-reviewed support, particularly for anti-inflammatory effects and specific conditions like peripheral artery disease. 

What this study challenges is the specific premise that declining blood NAD+ is a universal signal of aging in healthy people, and that you can meaningfully track your biological age through it.

If you're using a blood NAD+ test as a longevity metric, the research suggests you may be measuring something that doesn't reflect what you think it does.

Together With Momentous 
The Fiber Goal You've Been Given Is Misleading

Most people who pay attention to fiber have been told to eat 25 grams per day. Hit it, and you're good. What the recommendation doesn't tell you is what happens if you eat more. 

A meta-analysis of 19 large studies following nearly 2 million people found that fiber's protection against colorectal cancer doesn't stop at the recommended amount. Each additional 10 grams is associated with a 10% lower risk, and the benefit continues to increase beyond 40 grams per day.

Think of your gut as a long tube with billions of tiny workers (bacteria) living inside it. Fiber is their food. When they eat it, they produce compounds that protect your intestinal lining and reduce inflammation, which helps protect you against health threats. 

Fiber also bulks up waste and moves it through faster, meaning harmful substances spend less time pressing against your colon wall. And it slows how quickly food breaks down into sugar, keeping your blood sugar steadier throughout the day. 

These aren't minor, isolated effects, either. They build on each other, which is why fiber keeps showing up across research on heart disease, diabetes, cancer, and longevity.

The UK's Scientific Advisory Committee on Nutrition reviewed the full body of evidence and set its official target at 30 grams per day, which is higher than the US recommendation. A separate analysis of 8,300 people with diabetes showed meaningful benefits climbing to 35 grams per day. 

When independent research teams in different countries keep arriving at the same conclusion across millions of people, that's not a trend worth waiting on.

And here’s why we’re telling you: Research consistently shows you misjudge your own fiber intake by 40 to 50 percent. 

You grab a "whole grain" wrap and assume you're covered, but that wrap might have 2 or 3 grams, at best. A small bag of trail mix might have 1. The average American actually gets about 14 grams per day, roughly half the floor, nowhere close to the range where protection peaks. Most people aren't optimizing. They're not even close to the starting line. But we want to help you close the fiber gap and improve your health.

The fix doesn't require a new diet. A half cup of black beans has about 8 grams. A cup of raspberries adds another 8. A bowl of oatmeal brings 4. Lentils, avocado, broccoli, and an apple with the skin still on. None of these are exotic; they're foods most people already like but eat inconsistently. Add one per day, and you'll close most of the gap without touching anything else.

If you want help closing the gap, we created Fiber+ to deliver 6 grams of fiber per serving from three distinct sources. Each serving includes soluble fiber, which slows glucose absorption and supports healthy cholesterol; an insoluble fiber, which adds bulk and promotes regular transit; and resistant starch, a clinically validated prebiotic that ferments in your colon into butyrate — the compound that feeds and protects your intestinal lining. 

It's the same three-pathway mechanism the research keeps pointing to, and in one serving, you can mix into anything and give your body what it needs.

The Pump Club team invested 2 years of R&D to help formulate the product with Momentous. It's NSF Certified for Sport, free of artificial additives, and available in unflavored or pure cinnamon.

Use the code PUMPCLUB to save 35% on your first subscription, or 14% off a one-time purchase. 

Whole foods get the job done, and Fiber+ fills the gap. 

Tools And Resources
Not Sure How Much Fiber You Eat? We Can Help

If you want to know exactly where you stand, the Fiber Gap Quiz takes two minutes and shows you how much you’re eating, how much more you need, and the moves that will matter most.

Nutrition
Use It Or Lose It: The 30-Minute “Anabolic Window” 

How important is it to have a meal immediately after your workout?

You've seen it at the gym or read it somewhere along the way: the moment you finish your workout, there’s urgency to eat. No matter what, you need to chug a protein shake before you’ve even caught your breath. 

The belief driving that behavior — consume protein within 30 minutes of training or your gains are wasted — is one of the most persistent myths in fitness.

Multiple systematic reviews and meta-analyses, analyzing data from hundreds of subjects across dozens of trials, have reached the same conclusion: 

When total daily protein intake is controlled, timing has no statistically significant independent effect on muscle growth or strength. 

The anabolic window is technically real, but it's not a small window or urgent. If you eat within 4 to 6 hours of your workout (the duration depends on how long it’s been since your last meal), and you’re giving your body the nutrients it needs over the course of the day, then you will see results. Speeding up when you have your post-workout meal doesn’t give you any additional advantage. 

What actually matters: If you do any form of resistance training, eat anywhere between .6 to 1 gram of protein per pound of goal weight, spread across three to four meals (it can be fewer or more, based on personal preference). So if you want to weigh 180 pounds (81.6 kg), you would eat between 110 and 180 grams of protein per day. 

The daily total is the lever. The stopwatch is not.

The Positive Corner of The Internet
About Arnold’s Pump Club Editorial Standards

We do things a bit differently here, starting with transparency.

1. The Content: All APC emails are researched, written, and fact-checked by the APC editors (see bottom of the email), with written contributions from Arnold (noted with “Arnold’s Corner”). Links take you to original studies (not second-hand sources).

2. Does AI play a role? Not for the primary content, but it is used in two ways. The main items are original content written by the APC team. The summaries at the end are AI-generated based on the human-written content above. We also use an AI tool to review our interpretations of the research and ensure scientific accuracy. We don’t assume AI is right, but we use technology to hold ourselves accountable.

3. Yes, we have partners (all clearly noted by “Together With”). Why? Because it allows us to keep the APC emails free. We first test products, and then reach out to potential partners who offer ways to help you improve every day. The bar is set high, and to date, we have turned down millions in ad deals. (Example: we will not partner with any non-certified supplements or those without evidence in human trials). If we won’t buy the product, we won’t recommend it to you. And if there’s no evidence it works, then there’s no place for it here.

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Publisher: Arnold Schwarzenegger​

Editors-in-chief: Adam Bornstein and Daniel Ketchell