Caryn Zinn Dietitian

18/02/2026

US Dietary Guidelines: a meaningful shift in the right direction for metabolic health...

I was recently interviewed about the newly updated US Dietary Guidelines, which have (quietly) upended the traditional food pyramid (Link below if you're interested). While there’s been some confusion and controversy, there are several genuinely positive changes worth highlighting:

Key shifts:
- Protein moved to the top of the pyramid, with higher daily protein targets
- Greater emphasis on animal-source proteins, recognising their important contribution of key micronutrients
- Full-fat dairy now promoted, alongside
- Healthy fats described as butter and tallow, and a move away from the historic push for low-fat, lean-only meat sources
- Continued emphasis on fruit and vegetables, for a stronger micronutrient lens
- Clear messaging to prioritise whole foods over ultra-processed foods, and the removal of any amount of added sugars as a “nutritious” option

Two important things were largely omitted from the interview itself, but deserve attention:
1. A major step forward in the Guidelines is the formal acknowledgement that lower-carbohydrate dietary approaches may improve outcomes for people with certain chronic conditions. This signals growing recognition of insulin resistance as a central driver of metabolic disease, and legitimises evidence-based dietary strategies that target underlying pathology, not just symptoms.

2. There was also no opportunity for rebuttal to comments made by the other interviewee regarding alleged conflicts of interest (COIs) of the newly appointed Scientific Foundation who provided a scientific report in an advisory capacity for this set of guidelines. For balance, it’s worth noting:
- This is the first time in the history of the Guidelines that COIs have been transparently and voluntarily disclosed by authors – a positive step for accountability.
- Critics often overlook the substantial COIs present in previous and existing Dietary Guideline Advisory Committees (DGAC), including ties to ultra-processed food and pharmaceutical industries.

No set of guidelines will ever be perfect. But this represents a clear move away from decades of low-fat, high-refined-carbohydrate dogma and toward a more metabolically informed, whole-food-focused approach. That’s progress – and one we should engage with constructively rather than dismiss out of hand.

https://www.rnz.co.nz/podcast/the-detail/2026/new-dietary-guidelines-from-the-us-stir-the-pot.

It's not so much what's in the recommendations as how they were put together that's concerning some in the medical and nutrition worlds

03/02/2026

GLP-1 receptor agonist weight-loss medications: powerful potential, but only if we get the rollout right.

There’s a lot happening around these drugs right now, including Pharmac’s move toward funding Wegovy (link to article in the comments).

There’s no doubt this new generation of weight-loss medications offers real benefits. For many people, they lead to substantial weight loss and meaningful improvements in cardiometabolic risk factors. From a public-health perspective, funded access has the potential to be genuinely game-changing.

But the evidence is clear on one critical point: what happens when these drugs are stopped matters ... a lot.

A large systematic review in The BMJ shows that when weight-management medications are discontinued, weight is rapidly regained and cardiometabolic benefits are lost, often faster, and to a greater extent, than after behavioural weight-management programmes (link in comments).

This creates a real risk if rollout occurs without safeguards: sarcopenic obesity, where weight regain occurs predominantly as fat rather than muscle, potentially leaving people with poorer physical function and worse metabolic health after stopping treatment.

Weight-loss medications should not be framed as a standalone solution. The strongest long-term outcomes are most likely when they are embedded within a comprehensive metabolic-health approach that prioritises sustainable lifestyle change alongside pharmacotherapy.

Medications can be powerful tools, but only when used as part of a long-term strategy, not a short-term fix.

21/07/2025

Over the weekend, I had the privilege of speaking at the Osteoarthritis (OA) Aotearoa New Zealand Summit on weight management in OA.

My presentation was on the role of weight management and the emerging role of GLP-1 receptor agonists, specifically focusing on the science and clinical application of whole food, carbohydrate-reduction (i.e. low carb and ketogenic diets) particularly for their anti-inflammatory benefits.

While OA isn’t classically inflammatory like rheumatoid arthritis, low-grade inflammation is a key part of the disease process. What’s often overlooked is that excess body fat, particularly visceral fat, acts like an inflammatory organ, releasing adipokines that contribute to systemic metabolic and joint disease. Reducing this fat burden eases joint pain, supports movement, and improves quality of life.

The audience, physiotherapists, physicians, GPs, and people living with OA, were curious, open-minded, and genuinely engaged with the evidence supporting a metabolic health lens, even though it challenges mainstream nutrition guidance. The great energy and thoughtful discussion made it a refreshing experience, a real win for science, clinical care, and open dialogue.

Feeling grateful to the organising team for the opportunity to contribute to this important space.

17/07/2025

Do check out this interview with Dr Nina Teicholz, her work has been pivotal in what might just be a turning point in modern dietary history. The U.S. dietary guidelines are expected (hopefully!) to drop the long-standing limits on saturated fat. If that happens, it could spark a global ripple effect, shifting how national guidelines are framed and how we advise populations to eat.

This would also mean no more penalties for saturated fat in algorithms like our local Health Star Ratings or other food classification systems... the implications are huge. Removing these limits may also help dismantle some of the resistance to carbohydrate-reduction approaches. Despite favourable evidence for cardiovascular health, many still fear these diets might cause harm due to modest increases in saturated fat intake.

The evidence challenging saturated fat as a health villain has been building for years. Hopefully, this time it will finally be "seen" by those who’ve long ignored it.

Exciting times ahead; this could mark a real shift for the better, and a true endorsement of eating whole, unprocessed foods without the usual caveats like “as long as you remove the skin” or “cut off the fat from the meat”!

Science journalist Nina Teicholz discusses how a growing list of companies are implementing the MAHA policy on ‘America's Newsroom.'

16/07/2025

Fauja Singh: “The Turbaned Tornado”
The world’s oldest marathon runner, (114 years of age) who was still competing after turning 100 more than a decade ago, died in a hit-and-run this week. A totally unnecessary death, but a classic example of the “live long, drop dead” philosophy!

Just as an FYI, here are some of his lifestyle habits that may have contributed to his longevity:

Diet:
• Primarily vegetarian: simple, plant-based meals (curry, chapati, lentils, vegetables)
• Avoided fried foods and processed foods
• Ate modest portions and emphasised not overeating
Exercise
• Maintained daily walking and running habits well into his 100s
• Continued consistent, moderate physical activity for decades
Lifestyle and attitude
• Abstained from alcohol and smoking
• Practised positive thinking and strong sense of purpose
• Deeply connected to his faith (Sikh) and community
• Prioritised mental health, balance, and optimism
In his own words about his longevity: “I am happy. I am content. I do not have any greed. That is why I am at peace.”

A remarkable life that shows us how simplicity, purpose, and movement can sustain us for over a century. May we all find even a fraction of his inspiration and spirit. Rest in peace, Fauja Singh.

12/07/2025

More Wegovy press this week. This time warnings from a Doc. Yes he’s a bariatric surgeon, so you might think he’s protecting his patch, but actually he makes some on-point remarks about the role of UPFs in our modern world and the importance of whole food.

He mentions a term, ‘tachyphylaxis’- meaning tolerance, medically- which occurs with bariatric surgery 18-24 months after surgery - ie., as time goes on, the patient will get less and less benefit from the treatment. He reckons you’d get the same waning effect from GLP1s, but earlier and more profound.

I’m guessing this explains his attention to diet and lifestyle, very sensible methinks!

Dr Rowan French insists lasting weight loss can only be achieved through a balanced approach to psychology, exercise and nutrition.

03/07/2025

Wegovy comes to NZ...

I suspect many of you have been tuned in this week with the arrival of Wegovy in New Zealand pharmacies, a non-funded option for obesity treatment, costing individuals around NZ$500 per month.

Both myself and my colleague Prof Grant Schofield had the chance to share our perspectives in the media on this topic, if you care to have a listen.

🎙️ I spoke with Kerre Woodham on Newstalk ZB about the surge in demand for What the Fat! a book that we wrote and published 10 years ago on whole food carbohydrate reduction (which is still relevant and works, according to many who phoned in).
https://www.newstalkzb.co.nz/on-air/kerre-woodham-mornings/audio/caryn-zinn-dietician-and-co-author-of-what-the-fat-on-losing-weight-weight-loss-drugs/

🎙️ Prof Grant Schofield discussed Wegovy’s effectiveness in relation to its place in public health with Emile Donovan on Radio NZ. https://www.rnz.co.nz/national/programmes/nights/audio/2018993594/wegovy-makes-its-nz-debut

Plenty of interesting debate came to the surface, feel free to add your view in the comments…

Weight loss drugs are becoming increasingly sought after, with Wegovy hitting New Zealand pharmacies this month.  It’s currently not funded, and people will need a prescription to get it.  However, people are warning that weight loss drugs aren’t a silver bullet, and l...

16/04/2025

🖤 RIP Dr Richard Bernstein (1934–2025)

Sad to hear that Dr Richard Bernstein has passed away yesterday at age 90. A total legend in the low carb and type 1 diabetes space, his work changed lives around the world.

Diagnosed with type 1 at age 12, he used self-experimentation to pioneer home glucose monitoring and tight blood sugar control, decades before it became mainstream. Frustrated by the medical system, he went to med school in his 40s so he could help others do what he did: live a long, healthy life with diabetes.

His book Dr. Bernstein’s Diabetes Solution and his “Diabetes University” videos inspired thousands. He fought for one simple principle: every person with diabetes deserves normal blood sugars.

Thank you, Dr B. Your legacy will live on. 💙

07/04/2025

Local Kiwis (and global advocates of metabolic health if you're keen), our NZ health system’s failing us— and it's time to prioritise prevention, and demand change, together. Sign the Petition for Health Reform in New Zealand: https://prekure.com/petition/ Grant Schofield

Home > Sign the Petition Sign the Petition for Health Reform in New Zealand https://vimeo.com/1059931772?share=copy =0 Sign the Petition for Health Reform in New Zealand I’ve dedicated my entire career to one mission – helping people live healthier, longer lives. But right now, New Zealand is h...

30/03/2025

A much-needed addition to the field- finally a tailored food pyramid for a population group with insulin resistance and metabolic disease. This new paper addresses the many myths that are often alleged about low-carb diets, i.e., that they are nutritionally deficient, cause heart disease, increase mortality and have harmful side effects etc...
Great work by this team!

As the prevalence of chronic diseases persists at epidemic proportions, health practitioners face ongoing challenges in providing effective lifestyle treatments for their patients. Even for those patients on GLP-1 agonists, nutrition counseling remains a crucial strategy for managing these condition...

22/03/2025

Gotto keep pushing that message, even at ridiculously early hours of the morning.

https://links.streem.com.au/tvnz-one-20250319-80RPQn0tjK6IGinhlhOhlAEEzy?keywords

To flesh it out, our AUT research project aims to get metabolic health and lifestle medicine higher up on the agenda when it comes to delivering health care for communities with prediabetes and T2D.

For more information, check out our website. https://www.wholenz.org/research-project Feel free to peruse the site, and enjoy the free resources in the resources tab. If you want to be involved in the project, as a primary care team, please get in touch wholenz@aut.ac.nz

is a collective movement in NZ, representing a unified effort aimed at reversing pre-diabetes and T2diabetes in our communities. Our goal is to improve the way healthcare is delivered to those living with diabetes and more broadly, chronic disease, by promoting a whole food, carbohydrate-re...

23/10/2024

Results of the longest trial (5y) of carbohydrate-reduction for T2D (conducted by Virta Health) has just been published, and shows remission is achievable and sustainable. Remission was observed in 20 % of those enrolled at five years, and the majority of those in remission had sustained it for at least four years. Other outcomes show sustained improvements in body mass, HbA1c, triglycerides, HDLc, and inflammatory markers, with no significant change in LDLc and Total cholesterol. Read the paper to see how remission outcomes compare with other forms of treatment.

Anyone who still says there is no long term evidence showing this dietary approach is safe and effecive for T2D, is incorrect, there is evidence and it's looking looking good.

This study assessed the five-year effects of a continuous care intervention (CCI) delivered via telemedicine, counseling people with type 2 diabetes (T2D) on a very low carbohydrate diet with nutritional ketosis.