I’ve just returned from a quick trip to the USA, where I had the privilege of presenting at A4M Longevity Fest in Las Vegas. The theme was Redefining Medicine, with around 10,000 attendees, and the energy was buzzing. There was so much to see, do and learn.

But, after a busy eight weeks with significant international travel, this trip was very much a fly-in, fly-out. In all honesty, I probably only experienced about 20% of what the conference had to offer, and there were many people I had hoped to connect with but simply didn’t have the time. Next time, I will definitely be staying longer — it was a phenomenal event and one I highly recommend.

One thing that is obvious in the USA — and this was my third work trip there this year — is that the food culture is different. Portion sizes are much larger, sweetness is more intense, and it can be harder to avoid added and refined sugars, simply because they’re so ubiquitous.

The USA has one of the highest intakes of refined sugars and ultra-processed foods (UPFs), which aligns with higher rates of overweight and obesity, metabolic dysfunction and chronic disease.

But this isn’t just an American issue.

Sugar and UPFs have crept into daily diets across the globe, driven by powerful marketing that sometimes suggests highly processed products are healthy, when in reality they often contain additives, preservatives, hidden sugars and compounds that do little to support cellular health — and in many cases actively contribute to metabolic dysfunction.

This is now well documented. The Lancet Ultra-Processed Foods Series, published last month (November 2025), outlines strong links between UPFs and cardiovascular disease, type 2 diabetes and all-cause mortality. I recently shared this series via email and on my socials. If you missed the email, you can also find the details in a social post featuring myself with Dr Mark Hyman and Dr Robert Lustig — two of the world’s leading advocates for reducing sugar and ultra-processed foods. I included the links to the Lancet papers with this post if you’d like to explore the data further.

Do People Really Feel Better When They Reduce Sugar?

There’s no doubt — I see this consistently in clinic, and I’ve experienced it personally.

When people reduce or remove refined and added sugars from their diet, they often notice:

• weight loss and/or improved body composition
• more stable energy throughout the day
• improved sleep
• reduced cravings
• fewer energy crashes
• improved mood stability
  

But the real question I’m often asked isn’t “Do people feel better when they reduce sugar?”

It’s “Is sugar actually that bad?”

To understand this, we need to look beyond food culture and trends, and instead look at what sugar is doing to the body at a cellular and biochemical level.

Looking Beyond ‘Good’ and ‘Bad’ Foods

As someone who has worked in the field of nutritional genomics (gene–diet interactions) for over 20 years, I don’t look at food in isolation. I look at how food and nutrients interact with our DNA, our cells and our biological pathways.

This includes how food influences systems such as:

• inflammation
• hormone regulation
• blood glucose control
• detoxification
• methylation
• energy production
  

These systems need to work together for us to feel well, heal/ regenerate, maintain energy and support long-term health.

When you look at refined sugar through this lens, it becomes clear why it deserves your attention — particularly if you’re working on your health, such as trying to manage weight or metabolic issues, living with chronic or autoimmune conditions, or thinking about having a baby or healthy ageing. The food you eat is critical. 

Sugar: Energy — or a Stress Signal?

Sugar can absolutely provide energy — glucose is used by cells throughout the body. However, when refined or added sugars are consumed frequently and in high amounts, especially outside the context of whole foods, sugar begins to act less like energy and more like a stress signal.

Repeated blood sugar spikes stimulate insulin release, followed by rapid drops in glucose. Over time, this pattern can contribute to:

• blood sugar instability
• increased inflammatory signalling
• hormone dysregulation
• gut irritation
• energy highs followed by crashes
• mood changes and cravings

Sugar, Insulin and Hormone Balance

One of the most under-appreciated effects of high sugar and UPF intake is its impact on hormones.

Insulin and sex hormones
Chronic high sugar intake can lead to hyperinsulinaemia (persistently elevated insulin). Elevated insulin suppresses sex hormone-binding globulin (SHBG) — the protein that regulates how much oestrogen and testosterone are biologically active.

Lower SHBG means higher free oestrogen and testosterone, a mechanism well described in:

• PCOS
• insulin resistance
• metabolic syndrome
  

Oestrogen and aromatase
Insulin resistance and increased adiposity can increase aromatase activity (encoded by the CYP19A1 gene), converting androgens into oestrogen. This can contribute to:

• heavier or irregular cycles
• worsened perimenopausal symptoms
• symptoms associated with higher oestrogen exposure
  

Progesterone
Blood sugar instability and chronic physiological stress can disrupt ovulation and reduce progesterone production, contributing to PMS, cycle irregularity and fertility challenges.

Testosterone
In women, insulin resistance can increase free testosterone via reduced SHBG.
In men, high sugar intake and metabolic dysfunction are associated with lower testosterone levels, in part due to increased aromatase activity converting testosterone to oestrogen.

Genetics Matter

For some people, the effects of sugar are amplified due to genetic susceptibility.

Examples include:

• TCF7L2 variants influencing blood sugar regulation and type 2 diabetes risk
• FTO variants affecting appetite, carbohydrate handling and weight regulation
• inflammatory genes such as TNF-α, which can heighten inflammatory responses
  

This is just a very brief snapshot. There are many other genetic variations that influence how we respond to food — which is the foundation of nutritional genomics and personalised nutrition.

How Much Sugar Should We Be Having?

In Australia, the NHMRC Australian Dietary Guidelines recommend limiting foods and drinks high in added sugars, in line with global recommendations.

The World Health Organization (WHO) provides a clear quantitative guideline:

• Less than 10% of total daily energy from free sugars
• Less than 5% for additional health benefits
• Roughly 25–26 grams per day (about 6 teaspoons) for most adults

Importantly, these recommendations are based on reducing disease risk, not achieving optimal health.

Where Sugar Often Hides — and How It Adds Up

We tend to think of sugar as coming from obvious treats like lollies, cakes and desserts. But many people exceed recommendations through foods and drinks they believe are healthy.

Common sources include:

• drinks — fruit juices, flavoured drinks and smoothies
• flavoured yoghurts (especially low-fat versions)
• breakfast cereals and muesli bars
• packaged gluten-free products
• sauces, dressings and condiments
  

To put this into perspective:

• a glass of fruit juice can contain 5–6 teaspoons of sugar
• a low-fat flavoured yoghurt often contains 4–5 teaspoons
• sauces or dressings can add another 1–2 teaspoons
  

Together, that can easily exceed the entire daily recommendation — before you factor in breakfast cereal, a muesli bar, a packaged snack or a muffin later in the day.

Even foods we choose for health reasons can quietly add to our daily sugar load. For example, I personally choose oat milk in my coffee — I enjoy it. But I’m also aware that oat milk contains rapidly absorbed carbohydrates, largely maltose (a sugar made up of two glucose units), produced when oat starch is broken down during processing.

Oat milk isn’t an ultra-processed food, but it is processed — and it still contributes carbohydrates that affect blood sugar. On its own, that’s not a problem. But when combined with other foods and drinks across the day, these small, everyday choices can add up.

So, it’s not about one choice in isolation — it’s about the cumulative effect of everyday choices across the day and over time that matters. Oat milk may or may not be an issue for me, it depends on the other foods and drinks I choose to consume throughout the day. 

What About Sugar Alternatives?

When people reduce sugar, many turn to artificial sweeteners. While these may reduce sugar intake short-term, evidence suggests they can:

• overstimulate sweet taste receptors
• disrupt the gut microbiome
• maintain cravings for sweet foods
• offer little benefit for long-term weight or metabolic health
  

Stevia and monk fruit are natural, plant-derived sweeteners and can be useful short-term during transition. Small amounts of maple syrup or raw honey can also be appropriate when used intentionally.

Often, once taste buds recalibrate, real foods — like a delicious mango — taste incredibly sweet and satisfying on their own.

Reducing Sugar Without Deprivation

This is not about fear, restriction or perfection.

Food is pleasure. Food is social. Food is meant to be enjoyed.

Extreme restriction often leads to guilt, binge-eating and metabolic stress — none of which support long-term health.

If it’s a birthday, with Christmas is around the corner, or Aunt Betty makes an incredible pavlova — enjoy it. Celebrate.

The key is awareness and intention. Every choice sends a signal to your body, and when most choices support health, the occasional indulgence becomes exactly that: a conscious, fun, joy filled decision.

Final Thoughts — and Support If You Want It

Reducing refined sugar isn’t about obsession and deprivation — it’s about nourishing your mind and body.

When we prioritise real, whole foods, we create an internal environment that supports:

• stable energy
• hormone balance
• metabolic health
• beneficial gene expression
• long-term wellbeing
  

If you’d like support, reducing sugar is one of the first areas we focus on in the Whole Food Challenge. From there, we progressively explore other inflammatory foods and learn how to use food as nourishment — not punishment — to support health, energy and longevity.