5 Sneaky Ultra-Processed Food Ingredients That Harm Your Gut, Metabolism and Appetite

Ultra-processed foods (UPFs) are everywhere – from breakfast cereals and snack bars to plant milks, sauces and “health” treats. Most people know they are loaded with sugar and vegetable oils, but far fewer realise how many additives are specifically engineered to make these foods hyper-palatable, easy to overeat and hard to give up. If you have ever opened a packet and wondered why it is almost impossible to stop, these hidden ingredients may be part of the reason.

What are ultra-processed foods?

Ultra-processed foods are industrially formulated products made mostly from refined ingredients, oils, starches, sugars and additives rather than whole foods. They typically contain long ingredient lists with substances you would not use in a home kitchen, such as emulsifiers, artificial sweeteners, colourings and flavour enhancers.​

These products are designed to be cheap, convenient and intensely tasty, but high intakes are consistently linked with increased risk of obesity, type 2 diabetes, heart disease and poor gut health. The problem is not just calories; it is the way these foods interact with appetite, hormones and the microbiome.

1. Emulsifiers: smooth texture, upset gut

Emulsifiers help oil and water mix, creating the creamy, uniform texture in foods like chocolate, ice cream, margarine, plant milks and sauces. Common examples include lecithin, mono- and diglycerides of fatty acids, certain phosphates, xanthan gum and pectin.  ​

Emerging research suggests that some emulsifiers can disturb the gut microbiome, increase intestinal permeability and promote low-grade inflammation, changes that are associated with metabolic dysfunction and insulin resistance. Over time, this may influence how the body handles blood glucose and stores fat, even if total calorie intake does not change.

2. Flavour enhancers: louder taste, weaker fullness signals

Flavour enhancers such as monosodium glutamate (MSG) and yeast extract are used to intensify savoury taste and make products more appealing. They are common in packet soups, instant noodles, snack foods, sauces and processed meats.  ​

By amplifying flavour, these ingredients can encourage faster eating and make it easy to override natural fullness cues, especially when combined with refined carbs and fats. Regular consumption of heavily flavoured UPFs is linked with higher overall energy intake and a greater risk of obesity and metabolic disease.

3. Artificial sweeteners: sweet taste, mixed metabolic signals

Artificial and low-calorie sweeteners such as aspartame, sucralose and sugar alcohols like maltitol are widely used in “diet”, “light” and “no added sugar” products. They appear in soft drinks, protein bars, yoghurts, chewing gum and many “keto” or “diabetic-friendly” snacks.  ​

Although they are often promoted as a healthier alternative to sugar, studies associate high intakes of some sweeteners with altered glucose tolerance, insulin resistance and changes in the gut microbiome. These shifts may increase inflammation and raise the long-term risk of type 2 diabetes, despite little or no direct calorie contribution.  ​

4. Stabilisers and thickeners: better texture, possible microbiome changes

Stabilisers and thickeners such as carrageenan, xanthan gum, guar gum and various gelling agents are used to improve mouthfeel, prevent separation and extend shelf life in products like desserts, plant milks, yoghurts and sauces. They help create the creamy or silky texture that many people find appealing.  ​

While many of these compounds are approved as safe, newer studies indicate that some may change the composition and activity of gut bacteria in ways that are not yet fully understood. For susceptible individuals, this may contribute to digestive symptoms, low-grade inflammation or altered appetite regulation.

5. Food colourings: brighter food, higher risk patterns

Food colourings, both synthetic and some highly processed natural colours, are used to make products look more vibrant and attractive, especially to children. They are common in confectionery, cereals, flavoured drinks, snack foods and packaged baked goods.​

Artificial dyes have been linked in some children to hyperactive behaviour and increased risk of certain allergic reactions. High intake of brightly coloured, ultra-processed products also tends to go hand in hand with greater exposure to sugar, refined starches and unhealthy fats, a pattern associated with higher risk of obesity, heart disease and some cancers over time.

Why calories and “low fat” missed the mark

For decades, nutrition advice has centred on cutting fat and counting calories, with the assumption that a calorie is a calorie regardless of source. During this time, ultra-processed, low-fat and “diet” products exploded in number, yet rates of obesity, type 2 diabetes and metabolic disease continued to climb.​

Focusing only on calorie deficit ignores how food quality, processing and additives affect hunger hormones, blood sugar, gut health and reward pathways in the brain. Ultra-processed foods can promote chronic inflammation and dysregulated appetite, making it much harder to sustain a healthy weight and metabolic profile even when people try to “eat less”.​

A simple real-food formula that works

Instead of obsessing over calories and grams of fat, shifting attention to food quality and satiety can dramatically improve health and make eating well feel easier. A straightforward formula can help build meals that are nutrient dense, satisfying and kind to the gut.​

Try using this structure for most meals:

• Pick a protein: meat, fish, eggs, Greek yoghurt, cottage cheese, tofu or tempeh provide the foundation for fullness and stable blood sugar.​
• Add some veggies: non-starchy vegetables such as leafy greens, broccoli, cucumber, capsicum and zucchini add fibre, micronutrients and volume for very few digestible carbs, especially helpful if you are insulin resistant.​
• Add some fat if the protein is lean: options like extra-virgin olive oil, avocado, olives, nuts, seeds or a knob of butter boost satiety and help absorption of fat-soluble vitamins.​
• Add some flavour: herbs, spices, salt, citrus and fermented foods such as sauerkraut or kimchi make real food enjoyable without relying on artificial flavour enhancers.​

Using this formula, you end up with a nutrient-dense, minimally processed, highly satiating meal that supports a healthy gut and keeps you comfortably full for hours. Over time, eating this way tends to crowd out ultra-processed foods, reduce cravings and naturally align appetite with the body’s true energy needs.

Dr Mary Barson and Dr Lucy are the founders of Real Life Medicine. They help women who have been on every diet under the sun, optimise their health and achieve long lasting weight loss without feeling miserable or deprived.

They do this with their 3 step framework:

• Strategies to improve your metabolism
• Brain-based skills to overcome self-sabotage
• Tools to make it easy to implement

With this comes increased energy, vitality and confidence.

You can avoid chronic disease and stop living life on the sidelines!