As a registered dietitian, I often hear from people who feel like their metabolism is working against them. And truthfully, it might be—especially if certain foods are sneaking into your diet more often than you realize. Metabolism is your body’s engine, turning food into the energy you need to move, think, and thrive. But when it slows down, it can lead to frustrating weight gain, constant fatigue, and even sluggish digestion. While many people focus on what can boost metabolism, it’s just as important to know what may be sabotaging it. Surprisingly, even some foods that seem healthy can throw things off. The good news? A few smart swaps can get your metabolism back on track. Below are 7 common foods that might be slowing you down—and what to eat instead.
Highly Processed Sugary Foods
Examples of these are breakfast cereals, granola bars, and other foods packed with added sugar. Check the label and see the added sugar per serving and you’ll realize how much you’ll be eating. These sugary foods increase the blood sugar. This affects the metabolism and commonly result in the feeling of being sluggish. Long and constant intake may cause insulin resistance, making it harder to burn fat efficiently, according to research.
Artificial Sweeteners
They are a good alternative to sugar only if taken at the right amount. These artificial sweeteners like aspartame and sucralose have an effect on the gut bacteria, specifically altering the balance of the good and bad ones. This affects the nutrient absorption and metabolism, say studies.
Refined Carbohydrates
Examples of these are white bread, pasta, and pastries. They lack fiber and are quickly converted into sugar in the body which increases the insulin level fast, especially when not combined with lean proteins and high-fiber foods. Generally, they won’t directly cause the slowing of metabolism. It is how they are combined with other foods, as well as their serving portions.
Seed Oils
This has been a debate among many as it is believed that oils like soybean, corn, and canola are high in omega-6 fatty acids that can cause inflammation, slowing metabolism in effect. As a dietitian, I’d say that a diet high in omega-6s and low in omega-3s may affect metabolic disorders, but similar to refined carbohydrates, it depends on the serving portion and how they are combined with other foods. A diet with adequate omega-3s from fish, flaxseeds, and walnuts can mitigate concerns about excess omega-6. Also, when seed oils are taken in limited amounts.
Alcohol
A glass of wine here and there may be fine. But then again, excessive alcohol consumption will interfere with fat-burning processes. To explain further, the liver will prioritize breaking down alcohol over burning fat. This can slow metabolism and contribute to weight gain, say studies.
Dairy Alternatives with Additives
Many dairy-free alternatives like almond and oat milk usually contain added sugars, thickeners, and emulsifiers that can disrupt gut health and metabolism. Always check labels and always choose the. unsweetened versions.
Fried Foods from Fast Foods
Last but definitely not least, these fried foods contain unhealthy fats, refined carbs, and additives that slow the metabolism. Aside from contributing excess calories, fried foods promote insulin resistance and fat storage, say studies.
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Catherine Gervacio, RND, Certified Exercise Nutrition Coach