New research suggests that artificial sweetener sucralose, commonly used in many different products from diet fizzy drinks to ketchup, yoghurts to breakfast cereals, may leave us feeling up to three times hungrier than eating sugar

Research showed that those who reported being hungrier after eating food containing sucralose experienced heightened brain activity in regions involved with appetite. 

Artificial sweeteners have grown in popularity worldwide as awareness around the health risks of sugar has grown. Current recommendations suggest that no more than 5% of our calories a day should come from ‘free sugars’ (sugars added to food or drinks like cakes, juice drinks, biscuits, and chocolate) as well as sugars found naturally in honey, syrup, unsweetened fruit and vegetable juices, smoothies and purees. That’s no more than around 30g of free sugars for adults – less than the amount of sugar found in some cans of fizzy drinks. For those looking to reduce their sugar intake, sweeteners are often recommended, as they provide a similar taste without the added calories. However, a growing body of research suggests that sweeteners may come with their own sets of health concerns. Previous studies in both humans and rodents have shown that artificial sweetners can stoke hunger.

New research from Kathleen Page, MD, Associate Professor of Medicine and Co-Chief at the Division of Endocrinology and Diabetets at the University of Southern California, analysed the brain activity of 75 adults before and after drinking sucralose, sugar, and plain water. Participants aged 18 to 35 fasted overnight and rated their hunger before and after having the drinks, while researchers tracked neural activity for 35 minutes after each drink. 

Researchers found that bloodflow to a brain region involved in hunger (the hypothalamus) increased by around 3% after consuming sucralose, while drinking water or a sugar-sweetened drink decreased bloodflow by around 6%. When asked, participants reported feeling three times hungrier after drinking the sucralose drink compared to the sugary one. Researchers think that this could be because sucralose doesn’t trigger the release of insulin or GLP-1 (a hormone that plays an important role in regulating blood sugar levels and apetite), which tell your brain when food is eaten, meaning your body still thinks you are hungry. 

Increasing our hunger isn’t the only potential pitfall of artificial sweeteners. A 2023 study co-authored by researchers at the Harvard T.H. Chan School of Public Health looked into whether ultra-processed foods may cause an increased risk of depression. 

Researchers collected data on the diet and mental health from 31,712 middle-aged women enrolled in the Nurses Health Study II between 2003 and 2017, where participants filled out a questionnaire on their dietary habits every four years, as well as reporting if they received a clinical diagnosis of depression and/or started taking antidepressants during the study. None of the study's participants had depression when the research began.

Researchers discovered a link between artificial sweeteners and depression; the top fifth of consumers participating had a 26% higher risk of developing depression than those in the bottom fifth. 

Not all research into artificial sweetners paints a sour picture. A 2024 review into the chronic use of artificial sweeteners highlighted both the pros and cons of artificial sweeteners, including highlighting that artificial sweeteners can help to prevent tooth decay by reducing the amount of sugar consumed. 

Amongst the cons highlighted about artificial sweeteners, researchers emphasised the disruption they can cause towards gut microbiota (also known as gut microbiome and gut flora). Having a healthy gut microbiome can play an important role in helping with digestion, keeping bad bacteria away, reducing inflammation, as well as improving both your immune system and mental health. 

While more and more of us worry about our sugar intake and are concerned that we might be addicted to sugar, switching to sweeteners may feel like a positive first step in the right direction. But with a growing body of research into the potential downsides of some sweeteners, it could be a sign that making the switch is just that – a first step, not the end of the journey. 

As Nutritional Therapist and Functional Medicine professional, Olianna Gourli explains, limiting sugar can help with hormonal balance, healthy joints, decreasing mood swings and cravings, improving energy levels and sleep. 

If you are thinking of cutting back on sugar or sweeteners and trying to eat a healthier, more balanced diet, working with a nutritional professional can help to make overall lifestyle changes beyond switching from sugar to sweeteners. Able to support you towards specific goals, to help you make changes and develop healthier habits, as well as to focus on foods that can support your mental health and wellbeing, nutritional therapy can help with more than you might think.  

It’s easy to feel overwhelmed by new health messages and research, but these studies open up a valuable conversation about what we are putting on our plates – and why. Rather than just swapping one unhelpful eating habit for another, this could be a moment to rethink how we nourish ourselves. Whether you're just starting out or already on a health journey, now’s a great time to explore deeper, more personalised ways to support your health and wellbeing, and to find ways of putting your health first.