About David Wiss PhD
Dr. David Wiss is an independent thinker unafraid to challenge the status quo in the nutrition field. Dr. Wiss pioneered the field of nutrition for addiction recovery and is a world-renowned expert in disordered eating. His mental health research bridges gaps between neurological, psychological, behavioral, and nutritional sciences.
Dr. David has treated over 1,000 patients in the last twelve years using a food-positive functional medicine approach through his practice, Nutrition In Recovery. Dr. Wiss has developed innovative methods for using nutrition to improve mental health without feeling like a “diet.” Dr. Wiss believes gut health is the key to brain health and wants to show you how to heal yourself and help your clients.
Services
Dr. David Wiss brings his twelve years of experience as a mental health nutritionist to patients, treatment facilities, institutions, academics, and the press.
Treatment
Individual and family counseling, functional medicine, group facilitation
Consulting
Professional supervision, staff training, expert opinion/quote
Speaking
Academic conferences, podcasts, wellness workshops
Collaboration
Joint efforts on research, statistical analysis, manuscript writing
Research
With over 20 peer-reviewed journal publications, Dr. Wiss is dedicated to disseminating his findings and progressive perspectives at the intersection of nutrition and mental health.
Can intuitive eating be helpful to individuals with ultra-processed food addiction?
Intuitive Eating can be used in conjunction with other treatment modalities as a harm-reduction approach to reduce…
Abstinence-based treatment of comorbid eating disorders and ultra-processed food addiction
The evidence that ultra-processed food addiction exists and is impacting a subset of our clients with disordered…
Low carbohydrate and psychoeducation programs show promise for food addiction: 12-month follow-up
The current data demonstrate the long-term clinical effectiveness of a low carbohydrate “real food” intervention delivered in…
Training
Dr. Wiss is available to provide trainings to your staff or organization on mental health nutrition, addictions, disordered eating, and more.
Podcasts
If you would like to feature Dr. Wiss on your podcast, please send a message and we will gladly discuss a collaboration with you.
Blog
Capturing the larger systemic issues in the field, these blogs point to public health solutions. There exists great opportunity to integrate nutrition into behavioral health.
The White House Just Changed Psychedelic Policy. Here’s What That Actually Means — And What It’s Missing
Ultra-Processed Foods: Why You Can’t Stop Eating Them (and why it’s not your fault)
From The Socials
Something huge happened last week, and my reaction is complicated — which is exactly why I had to gather my thoughts. Overall, I think we’re moving in the right direction.
The research on psilocybin and ibogaine is genuinely compelling. For treatment-resistant depression, PTSD, and addiction, this door opening matters.
But we’ve watched this movie before. A powerful natural medicine gets discovered, patented, standardized — and the nuance disappears.
What the FDA’s fast-track criteria don’t account for is your unique biology — and those are exactly the variables I’m trained to think about. Psychedelic outcomes aren’t uniform, and the variation tracks with nutritional status, inflammation, gut-brain function, methylation, and cortisol patterns. These are active variables — not background noise.
Neuroplasticity is sensitive to metabolic conditions. Serotonin synthesis depends on tryptophan and B-vitamin status. Chronic neuroinflammation changes how an altered state is processed.
The better question has never been “did symptoms decrease?” It’s whether the person was prepared, supported, and tended to in the months after. I’m here for the nuance. Always have been. Always will be.
#PsychedelicMedicine #FunctionalMedicine #MentalHealthScience #TreatmentResistant #GutBrainAxis
You’ve been told you’re “treatment-resistant.” But when nobody has tested your gut, your hormones, your nutrient status, your genetics, or your cortisol patterns — what exactly has been tried?
At FxMed Mental Health, we specialize in the cases conventional psychiatry hasn’t solved — not because those cases are impossible, but because the right questions haven’t been asked yet.
If this resonates, save this post. Share it with someone who needs to hear it.
Book a free discovery call to unpack what this means for you 🫶🏼
#FunctionalMedicine #MentalHealthMatters #RootCauseResolution #TreatmentResistant
#GutBrainAxis
13 years of clinical work. A PhD. Training with the Institute for Functional Medicine. Custom AI models. And one realization: the future of mental health care requires a completely different approach.
Today I’m proud to announce FxMed Mental Health — a 6-month functional medicine program I built alongside a psychiatrist and health psychologist. We’re treating root causes, not just symptoms.
If you know someone stuck in the cycle of treatment-resistant mental health conditions, please share this. And if you want to talk — about the work, about collaboration, about anything — my door is open.
Deep love ❤️
#FunctionalMedicine #MentalHealth #NutritionalPsychiatry #RootCauseMedicine #IntegrativePsychiatry
Auto-Brewery Syndrome
This one stopped me in my tracks.
Auto-Brewery Syndrome. Your gut bacteria literally fermenting sugar into alcohol — inside your body — without you ever taking a drink.
People losing jobs, getting DUIs, having their families think they’re lying about drinking. For decades, doctors dismissed it. Patients were told it was in their heads.
It’s not in their heads. It’s in their gut.
A brand new study in Nature Microbiology (PMID: 41507585) finally mapped what’s happening at the microbial level — E. coli and Klebsiella pneumoniae overgrowth, fermentation genes switching on during flares, blood alcohol levels hitting nearly 3x the legal limit from endogenous production alone. And here’s what really got me: a fecal microbiota transplant put one patient into complete remission. 16 months and counting.
But here’s where it gets even more interesting for those of us working in mental health. Researcher Alan Logan and his team have been connecting the dots between gut microbial metabolism and cognition, impulse control, aggression, and mood. They coined the term “legalome” — because this science is literally changing outcomes in courtrooms (PMID: 41008344). DUI charges dismissed. The gut-brain axis isn’t a wellness buzzword anymore. It’s evidence.
Now — is Auto-Brewery Syndrome common? No. But the underlying mechanism — dysbiotic bacteria producing neuroactive metabolites that mess with your brain — that is incredibly common. And most people have no idea it’s happening.
This is exactly why I built a practice around comprehensive gut testing. If you’ve been dealing with unexplained brain fog, mood instability, cognitive issues — especially after antibiotics — the answer might not be in your head. It might be in your microbiome.
#autobrewerysyndrome
New research just dropped in Science Advances (PMID: 41616060) confirming something I’ve been passionate about for a long time: the vagus nerve plays a direct role in dopamine reward signaling 🤯
Let me say that again — your GUT is shaping how your brain experiences pleasure and motivation. This ain’t woo. This is neuroscience 🧠
As someone who works at the intersection of nutrition, mental health, and addiction, this hits. So many of the clients I’ve worked with over the years have had significant GI issues alongside their mental health struggles. And for too long, we’ve treated those as separate problems.
They’re not.
The vagus nerve — “the wanderer” — connects it all. And when it’s compromised by trauma, chronic stress, or dysbiosis, it sets the stage for everything from disordered eating to substance use.
The encouraging part? Vagal tone is something we can influence. Breathwork, yoga, cold exposure, mindful eating, gut-supportive nutrition — these aren’t just wellness trends. They’re evidence-informed strategies for healing the gut-brain axis.
If you or someone you know is in recovery, dealing with chronic gut issues, or working through trauma — this is worth grasping.
Drop a 🧠 if you learned something new.
#VagusNerve #GutBrainAxis #Addiction
I came into the nutrition field believing we could change things. Better food, better health, better outcomes — it felt straightforward enough. But the more I learned, the more I realized the system wasn’t broken. It was working exactly as designed — just not for the people it’s supposed to serve.
So I started studying why. Why do well-intentioned efforts keep failing? Why does the science get ignored? Why do the companies causing the most harm keep getting more powerful?
The answer has a name: the commercial determinants of health. It’s the framework that explains how corporate actors shape our food environment, influence our professional organizations, fund the research that suits their interests, and lobby against the policies that would actually protect people.
This article from Knowable Magazine lays out something I’ve been talking about for years — we don’t even track corporate crime the way we track street crime. There’s no centralized database. No national statistics. The last comprehensive federal report was from 1979. That’s not an accident. That’s by design.
But here’s what gives me hope: the conversation is shifting. Researchers, clinicians, and advocates are connecting these dots in ways that weren’t happening even five years ago. Legislation is being reintroduced. People are waking up to the fact that their health struggles aren’t just personal failures — they’re predictable outcomes of a system that prioritizes profit over wellbeing.
It’s an uphill battle. It always has been. But for the first time in my career, it actually feels like we’re gaining ground.
Are you feeling optimistic or nah?
I found yoga about 12 years ago after years of heavy lifting. Truthfully, my body resisted it at first. My muscles were constantly sore and tight, and the stretching was uncomfortable. But after a few months of easing in, something shifted. I went from lifting 5x/week to yoga 3x/week with lighter weights in between. I lost some muscle mass — but my anxiety dropped significantly. My whole world opened up 🧘🏽
I’m convinced that trauma stored throughout my fascia tissues was released. Science is beginning to support this hypothesis 🧬
That led me to yoga retreats with @brentasana and @jaycoyoga — still some of my best memories in this life. Then the pandemic hit, then two kids, and my practice fell off. Sound familiar?
In recent months, I’ve gotten serious again. I’m practicing at @yogazan in Santa Monica (shoutout to @dianemagnette classes) and hoping to get my wife @miracleworkher on the mat with me soon 👰🏻♀️
Here’s what I wish I’d understood earlier: yoga isn’t just exercise. It’s a nervous system reset. A new systematic review (PMID: 41108584) looked at 10 clinical studies on yoga for IBS and found moderate-to-large effect sizes for reducing GI symptoms — in one trial, yoga performed as well as a low-FODMAP diet. The mechanism? Yoga restores vagal tone, the connection between your brain and gut. When stress tanks your vagal tone, digestion suffers.
The poses matter. But the breathing might matter more 🧎🏻♂️
I compiled specific poses matched to specific GI symptoms — bloating, constipation, diarrhea, stress-driven gut issues. Save it. Try them. Your gut will tell you if it’s working.
#yoga #guthealth #ibs #ibsrelief #functionalmedicine
New research just dropped in the BMJ, and it’s a big deal…
Transnational food corporations are now marketing “healthy” ultraprocessed foods — think high-protein snacks, vitamin-enriched drinks, and plant-based burgers — as solutions to the very problems their products helped create. This new analysis from Rezende et al. (2026) exposes exactly how this narrative is being used to undermine front-of-pack labeling, block marketing restrictions, and delay real policy change.
Here’s what the data actually shows:
📊 92 out of 104 cohort studies link UPF consumption to at least one adverse health outcome — obesity, type 2 diabetes, cardiovascular disease, cancer, mental health disorders, and all-cause mortality.
📊 UPFs now account for more than 50% of calories consumed in the US and the UK.
📊 The mechanisms go beyond nutrients. Mediation analyses and randomized crossover trials indicate harms associated with the processing itself.
The industry’s playbook? First, it was “no food is harmful in moderation.” Now it’s “only SOME ultraprocessed foods are bad.” The goal is to fragment the science and confuse the public so that meaningful regulation never arrives.
But the world is catching on. More than 10 countries have incorporated the NOVA classification into dietary guidelines. Brazil restricts UPFs in schools. Colombia has introduced UPF taxes and mandatory front-of-package warnings. California recently passed legislation restricting certain UPFs in school meals due to harmful additives.
So what can we do RIGHT NOW?
Check out @nonupfprogram — a nonprofit certification program that is putting real pressure on the food industry to be transparent about what’s in their products. Food companies can now get certified as Non-UPF, giving consumers a clear signal at the point of purchase. This is a huge step toward holding Big Food accountable and recognizing the companies that are actually committed to public health over private profits. Certification is available now.
This is not fringe science. It has been published in the BMJ, The Lancet, and Diabetes Care. It’s driving global policy. And it demands systemic change — not just individual behavior change.