You might think you’re eating a fairly healthy diet. Maybe you avoid fast food or sugar to your tea. But hidden fats and sugars are everywhere, and many everyday foods that seem healthy can quietly overload your system. For example, flavoured yoghurts, packaged cereals, granola bars, salad dressings, and fruit juices often contain large amounts of added sugar. Similarly, processed snacks, baked goods, and ready-to-eat meals are often packed with unhealthy fats. 

Unknowingly, they are getting into our systems and wrecking our health in ways that go far beyond our waistline. The hidden damage they cause is often overlooked and misunderstood. While we may only attribute high-fat and high-sugar diets to our increasing waistlines, what we don’t see is how these diets silently affect our brain, liver, gut, metabolism, and even future generations. Keep reading to know how these diets can impact our overall health.

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5 Ways High Sugar and High Fat Diet Affect Your Health

Poor Cognitive Function and Spatial Navigation Ability

A 2025 study published in the International Journal of Obesity reveals that a high-fat, high-sugar diet doesn’t just harm your physical health, it also affects brain function. In particular, it impairs memory and the ability to navigate spaces, skills linked to the brain’s hippocampus. Participants who consumed less junk food performed better in spatial tasks, like remembering routes in a virtual maze. These findings underscore how poor dietary habits can subtly impact cognitive abilities essential for everyday functioning.

The good news? The researchers say these brain effects can likely be reversed by improving your diet. Making smarter food choices now may help protect your memory and thinking skills in the long run.

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Induce Metabolic Syndrome

A high-fat, high-sugar (particularly high-glucose) diet has been shown to trigger early signs of metabolic syndrome (MetS), a condition that increases the risk of type 2 diabetes and heart disease.  In a 2018 animal study published in Nutrients, rats fed this high-fat high-sugar diet gained weight, had increased abdominal fat, showed impaired glucose tolerance, and developed signs of oxidative stress and nerve sensitivity. Interestingly, the study highlighted that glucose (also known as dextrose in the food industry) may play a bigger role than fructose in driving metabolic syndrome when combined with high fat.

These findings show that we might be ignoring how much harm glucose (a type of sugar often added to processed foods) can cause when eaten with a high-fat diet. All processed and packaged snacks, sweets, sugary drinks, and fast foods are loaded with both sugar and fat. This is a clear sign to limit the consumption of highly processed and packaged foods.

Related story: 7 Ways to Control High Blood Sugar In The Morning

Predispose Offspring to Lifelong Health and Behavioural Risks

A pregnant woman's high-fat, high-sugar diet may have consequences for later generations, a mouse study by Washington University, USA indicates. The study suggests that a mother’s obesity can cause genetic abnormalities that are passed through the female bloodline to at least three subsequent generations. This eventually increases the risk of obesity-related conditions.

Another 2017 study published in the Journal of Physiology found that high-sugar and high-fat diets increase the risk of metabolic syndromes in offspring, including obesity, insulin resistance, and type 2 diabetes. It also affects brain development by interfering with key brain receptors in the prefrontal cortex. It is an area involved in memory, decision-making, and self-control. These issues might lead to difficulties with learning and memory. 

In addition, a 2024 research published by the University of Australia, babies born to women consuming a high-fat, sugary diet are at greater risk of cardiovascular disease and diabetes in later life.

Related story: Sugar Substitute: Healthy Sweetener Alternative For People With Diabetes

Negatively Alter Gut Microbiota

A 2023 study published in the journal Nutrients highlights how a high-fat, high-sugar diet can quickly disturb the balance of gut microbes, even within a single day. In mice fed such a diet, researchers observed a drop in helpful bacteria (like Bacteroidetes) and a rise in others (such as Firmicutes and Proteobacteria), which are linked to health problems. 

These imbalances in gut bacteria can contribute to metabolic diseases like obesity and type 2 diabetes by increasing the amount of energy absorbed from food. Not only this but high-fat and sugar diets disrupt how fat is processed in the liver and fat tissue, and raise certain amino acids in the blood that can lead to insulin resistance.

Related story: Does Exercise Help Lower Blood Sugar

Increase the Risk of Non-Alcoholic Fatty Liver Diseases

A 2023 study published by the University of Missouri-Columbia established a link between diets high in fat and sugar and the development of non-alcoholic fatty liver disease, the leading cause of chronic liver disease.

The research team found that when mice were fed a high-fat, high-sugar diet, they developed a type of gut bacteria called Blautia producta and a lipid that triggered liver inflammation and fibrosis. This led to a serious condition called non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH), which closely resembles the same disease in humans. The study highlights how changes in the gut can directly affect the liver. This shows a strong gut-liver connection. What you eat not only impacts your digestion but also your liver health through the gut microbiome.

Need all your wellness solutions in one place? A whole new world awaits just a click away.

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