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Today’s Health Upgrade
The truth about DNA-based diets
Are you worried about the wrong nutrients?
Why your brain might be shrinking (and how to stop it)
He thought he was having a stroke — and then everything changed
Beyond The Headline
Does Your DNA Determine Your Diet Needs?
The pitch is compelling. Spit in a tube, mail it off, and receive a personalized diet tailored to your genetic code. No more guessing. No more advice that doesn't account for your unique biology. For a few hundred dollars, you get answers that feel scientific and specific, which is exactly why millions of people have bought in.
But behind the big promises is a reality that’s getting harder to ignore.
A new 12-month randomized controlled trial found that gene-based dietary recommendations produced the same weight and metabolic outcomes as standard nutrition counseling.
Researchers examined overweight or obese adults and split them into two groups: one received standard evidence-based weight management advice; the other received recommendations tailored to three genetic variants (FTO, UCP1, and TCF7L2) linked to body weight, caloric needs, and dietary fat metabolism.
Both groups worked with registered dietitians for six months, then followed their plans independently for another six months.
At the end of 12 months, weight loss, BMI, waist circumference, body fat, blood sugar, and cholesterol were virtually identical between groups.
The gene-informed group changed their eating patterns in ways aligned with their genetic profiles. Those changes just didn't produce better results.
This isn’t the first study to test DNA diets, and most studies have found similar outcomes. The likely explanation isn't that genes are irrelevant to nutrition; it's that the handful of variants tested by most commercial services represents a very small slice of an enormously complex biological picture.
But here’s what matters: Genes might influence tendencies, but they don't override fundamentals. Consistent caloric balance (or deficit if weight loss is required), covering your nutrient needs to manage appetite (such as protein and fiber), and controlling lifestyle variables that can affect hunger help deliver results, regardless of which variant you carry.
There are many great reasons to test, and your blood can reveal nutrient deficiencies. But that is different than a DNA analysis for your diet. The science is young, and things could change. But if you’re spending extra money to personalize your diet based on your genes, you’re likely paying a premium for no additional advantage.
Together With Function
You're Probably Worried About the Wrong Nutrients
Most people who care about their health have a supplement drawer. There's usually iron in there, maybe B12, probably zinc. The problem is that for many people, those may not be the right gaps to address.
A large-scale analysis covering more than 12,000 U.S. adults shows that about 73% of supplements are taken without clinician guidance, while only 27% are based on a doctor’s recommendation.
This suggests that many people are making long-term supplement decisions without insight into their actual nutrient status.
The practical question isn't whether to supplement. It's whether you're supplementing for the right things.
For example, a meta-analysis of 117 studies representing more than 45,000 participants looked at the effects of individualized nutritional assessments. The results showed significant improvements in weight management and cardiovascular risk markers, supporting the case for personalized health strategies.
That’s the issue with using population-level data and group averages as your guide: They can tell you what's true for many people, but not necessarily what's true for you.
A powerful way to learn about gaps — the ones that may actually need to be addressed — is to test. That's why we recommend Function. You get 160+ lab tests a year, including a detailed micronutrient panel that tells you where your levels stand: your vitamin D, your magnesium, your calcium, and more. Not a national average. Yours.
Results come with clinician-reviewed insights to help you understand what each number means and how you can address it. Many people who test find their numbers are largely fine, and more peace of mind is worth something on its own.
But testing can allow you to learn about a real gap. Something worth addressing that otherwise could have stayed invisible.
As an Arnold’s Pump Club reader, you get a $25 credit toward your first Function membership. The discount is automatically applied at checkout. No code needed.
There’s no need to blindly supplement. Testing can help uncover imbalances and gaps you might not notice, so you can make more informed, proactive decisions about your health.
Instant Health Boost
Your Brain Might Be Shrinking (And Belly Fat Might Be The Cause)
Fat loss gets sold on appearances. The six-pack. The before-and-after. Looking lean by summer. And while there's nothing wrong with wanting to look good, that framing keeps missing something the evidence keeps finding: what happens to your body when you lose fat offers much more than just how you look in the mirror.
In a 16-year study, people who lost the most belly fat — specifically the deep fat surrounding the organs — had significantly less brain shrinkage and better cognitive scores later in life.
Researchers tracked middle-aged adults after they completed one of four lifestyle intervention trials, using MRI scans to measure both deep abdominal fat (called visceral fat) and brain volume at multiple points over time. Two people could lose the same amount of weight, and the one who shed more visceral fat gained a clear advantage in brain health. And that advantage persisted for years after the original intervention ended.
The scientists suggest that losing fat is important for brain health, and that not all fat affects your cognition equally.
Subcutaneous fat — the kind you can pinch — didn't produce as big a difference as visceral fat, which is the deeper fat that wraps around your organs and behaves differently in the body.
The researchers believe that accumulating visceral fat affects blood sugar control. And when you keep gaining fat, issues compound, and it can affect brain health.
This was an observational follow-up study, so it shows an association, not a cause. And 86% of participants were men, which limits how broadly the findings apply right now.
At the same time, especially when combined with other studies on fat accumulation, it’s hard to ignore the signal. While you don’t need to be shredded, too much body fat increases your risk of many diseases and health problems, and that includes your brain.
Focus on dietary changes that will help promote fat loss, incorporate resistance training and general aerobic movement (even walking), prioritize sleep, and try to offset the stressors in your life (because not all stress is avoidable).
Pump Club Success Stories
The Wakeup Call: From Potential Stroke to 80 Pounds Down
Real People. Real Stories. Real Limits Overcome.
My name is Christian, and I'm about to be 43. I'm a father of 3, and about 3 weeks after my youngest daughter was born, I thought I was having a stroke.
My left arm went numb, and I ended up in the hospital. I got lucky, and everything was ok, but at 5'6" and weighing 251 pounds, I knew something had to change. My sister sent me the Pump Club app, and I haven't looked back.
I’ve been working out for 96 straight weeks, and I've lost 80 pounds.
I started with bodyweight programs, barely able to do 5 knee pushups, and now I'm doing intermediate programs with only dumbbells in my basement.
When Arnold said he didn't believe in diets and that your brain needs carbs, I naturally laughed. But that was the point where I changed my thinking.
My A1C dropped from 6.3 to 5.3, and I still eat carbs. I feel great, I'm wearing clothes that haven't fit since high school.
Want to turn around your health? Join the app, enjoy 7 free days, and experience the difference in the positive corner of the internet.
Better Today
Take any of these tips from today’s email and put them into action:
1. A 12-Month RCT Tested DNA-Based Diets Against Standard Nutrition Counseling. They Performed Identically.
A year-long randomized controlled trial found that dietary recommendations tailored to three genetic variants (FTO, UCP1, and TCF7L2) produced outcomes identical to those of standard nutrition counseling across all major markers examined, including weight loss, BMI, waist circumference, body fat, blood sugar, and cholesterol. The gene-informed group did change their eating patterns in ways aligned with their genetic profiles. However, those changes just didn't translate into better results. Genes may shape tendencies, but the evidence consistently shows that caloric balance, adequate protein and fiber, and consistent portions deliver results regardless of which variants you carry.
2. The Problem With Basing Your Supplement Decisions On Population Averages Or Without Identifying Personal Deficiencies
A large-scale analysis of more than 12,000 U.S. adults found that roughly 73% of supplement decisions are made without clinician guidance, meaning most people are supplementing based on general assumptions rather than their actual nutrient status. A separate meta-analysis of 117 studies covering more than 45,000 participants showed that individualized nutritional assessment produces significant improvements in weight management and cardiovascular risk markers, outcomes that population-level recommendations reliably miss. The practical implication: without testing your actual levels, you can't know whether you're addressing a real gap or spending money on something your body doesn't need.
3. The Fat That Shrinks Your Brain
In a 16-year follow-up study using MRI scans, middle-aged adults who lost the most visceral fat — the deep fat surrounding internal organs — showed significantly less brain shrinkage and scored better on cognitive tests than people who lost similar total weight but less visceral fat. The association was specifically with visceral fat, not subcutaneous fat (the kind you can pinch), suggesting visceral fat's distinct effects on blood sugar regulation might play a role. This was an observational study, and 86% of participants were men, which limits the generalizability of the findings. But combined with existing evidence on fat accumulation and metabolic health, the signal is consistent: too much body fat, particularly the deep kind, raises the risk of cognitive decline, alongside the cardiovascular and metabolic consequences already well-established.
The Positive Corner of The Internet
About Arnold’s Pump Club Editorial Standards
We do things a bit differently here, starting with transparency.
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).
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.
Yes, we have partners (all clearly noted). 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
