If you’ve ever tried to shed excess pounds, you know that losing weight can be a complicated (and frustrating) process. Not all foods—or calories, for that matter—are created equal, and just as some foods can expedite your weight loss journey, others can derail it quickly.

Here, three health experts explain which types of foods fall into the latter category—and what you should eat instead.

Foods with emulsifiers

Why they are harmful: Many processed foods, like ice cream, mayonnaise, margarine, chocolate, bakery products, and sausages, contain emulsifiers, which are chemicals that help blend together ingredients that would not naturally mix well together (e.g. oil and water), explains NYC-based registered nurse Rebecca Lee. Emulsifiers also make food look appealing, keep it fresh, and prevent molding. That may all sound harmless, but a study on mice found that consumption of these chemicals may do a number on your body by altering gut bacteria, triggering inflammation and increasing the risk of obesity and heart disease.

Check labels carefully to see if the food you’re consuming contains emulsifiers. Common emulsifiers include: lecithins, mono- and di-glycerides, polyglycerol ester, sorbitan ester, PG ester, and sugar ester.

What to eat instead: Where possible, opt for unprocessed foods like fresh fruits and vegetables, farm fresh eggs, legumes, nuts, and seeds.

Foods with MSG

Why they are harmful: Monosodium glutamate (MSG) is a highly addictive flavor-enhancer commonly used in fast food (like Chick-fil-A and Kentucky Fried Chicken), Chinese takeout, ramen noodles, canned foods, processed meats, and numerous other prepackaged foods, explains Lee.

Regular consumption of MSG-laden foods is linked to weight gain, as well as many other health issues. A study of 750 Chinese men and women found that those who used the most MSG in their cooking were nearly three times more likely to be overweight than those who didn’t use any, she explains. Even scarier, the increase in obesity risk was independent of physical activity and total calories consumed.

Other MSG-linked conditions include fibromyalgia, fatty liver and liver toxicity, high blood sugars, asthma, high cholesterol, high blood pressure, neurological brain disorders, digestive disorders, and metabolic syndrome, says Lee.

MSG can be disguised by more than 40 different names, explains Lee. Key terms that may denote its presence: glutamate, anything “hydrolyzed”, yeast extract, gelatin, soy protein, soy or whey protein, soy sauce, anything “…protein”, and calcium or sodium caseinate. MSG is hard to avoid because the FDA requires it to be listed on the label only if it’s used as a main ingredient, and not if it’s used only as a processing agent, which is a very common practice, explains Lee.

What to eat instead: Seek out foods that are minimally processed and seasoned with simple spices. Even better, flavor your meals with chile peppers for an extra metabolic boost. (Numerous studies suggest that capsaicin, the compound in chile peppers that gives them their heat, also raises metabolism).

RELATED: 5 Foods to Rev Up Your Metabolism

Artificial sweeteners

Why they are harmful: Many people use zero-calorie sugar substitutes as a weight-loss tool, but these sweeteners may actually have the opposite effect, says Lee. In a mice study, those who were fed artificial sweeteners saccharin, sucralose or aspartame developed glucose intolerance, a metabolic condition associated with obesity and type 2 diabetes. “The artificial sweeteners altered the animals’ gut microbiomes towards a balance of bacteria associated with metabolic diseases,” says Lee. What’s more, in a follow-up study on 7 human volunteers, 4 became glucose intolerant after consuming the maximum recommended dose of saccharin for just one week.

What to eat instead: Consuming too much regular added sugar isn’t good for you either, so satisfy your sweet cravings the natural way with whole fruits, cinnamon, nut butters, or sweet potatoes.

RELATED: What’s Better? Sugar-Free, No Added Sugar or Unsweetened

Refined carbs

Why they are harmful: Eating a diet high in refined carbs (think: pasta, bread, sweets) will cause a surge in blood sugar, which will trigger your pancreas to produce insulin to help clear the sugar from your blood, explains New Jersey-based registered dietitian Jeanette Kimszal. That translates into your body digesting and absorbing food more rapidly, which can cause energy crashes later on and damage your metabolism in the long term.

What to eat instead: Reach for complex carbohydrates consisting of whole grains and vegetables, like quinoa or spaghetti squash. “They contain fiber, which will slow digestion and keep your metabolism in check,” explains Kimszal. “Look for whole grain products that have at least 3 grams of fiber per serving and do not contain the words ‘enriched’ on the package.”

Low-fat products

Why they are harmful: Most of us tend to assume that foods labeled ‘low-fat’ are good for weight loss, which in theory makes sense, given the fact that gram for gram, fat has twice as many calories as proteins and carbs. But in a study published in the journal Appetite, researchers analyzed nutrition information for nearly 6,000 foods in Canada and found that, overall, products with low-fat claims were not significantly lower in calories than their full-fat equivalents. What’s more, “low-fat foods may even lead people to consume extra calories,” says Lee. A separate study investigating the effects of different fats on satiety found that participants were less hungry two hours after eating regular muffins compared to fat-free muffins.

What to eat instead: Instead of avoiding fat, rev up your metabolism by consuming good-for-you fats, like the omega-3’s found in salmon, tuna, mackerel and other cold water fish.

Soda

Why it is harmful: “Because it contains high fructose corn syrup (HFCS), soda can cause metabolic syndrome, which is a group of conditions (increased blood pressure, high blood sugar, excess body fat around waist) that occur together, increasing your risk for heart disease, stroke, diabetes,” says Tanya Zuckerbrot, NYC-based registered dietitian, author of The F-Factor Diet and creator of F-Factor. Fructose, when consumed in the same quantities as other sugar, has more damaging effects on the metabolism, she adds. A study published in the American Journal of Clinical Nutrition found that HFCS may lead to obesity because of its negative effects on the metabolism.

What to drink instead: Get your fizzy fill with Kombucha, a carbonated, fermented tea that’s loaded with probiotics, recommends Zuckerbot. Probiotics have been shown to help regulate digestion, weight and metabolism.