Over the past 30 years, low-fat diets have been touted as the key to weight management. But even as the calories from fat in people’s diets have decreased, obesity rates continue to climb. So what’s going on here? Sugar.  According to the Centers for Disease Control and Prevention, the average American adult consumes 71 grams (about 17 teaspoons) of added sugar each day. For perspective, the American Heart Association recommends no more than six teaspoons of added sugars a day for women and nine for men. Sugars added during food processing and manufacturing come from sucrose—table sugar, made from sugars found in fruits, vegetables, and nuts—and dextrose, which is made from starches like corn or wheat. Foods with these added sugars are typically lower in fiber and can cause blood glucose levels to spike more quickly.

There are also naturally-occurring sugars. Unlike added sugars, naturally occurring ones come from fructose—a sugar found in fruit and certain vegetables—and lactose in dairy products. Most of these foods also contain fiber, which helps you maintain blood glucose levels and feel full for longer. 

While it’s still unclear how sugar alone directly impacts obesity, eating too much of the added sugars can lead to excess fat and weight gain.  

Here are six not-so-sweet things you need to know about added sugar.

Foods made with added sugars tend to be higher in calories than those with naturally occurring sugars. Plus, they often  lack nutrients like vitamins, minerals, protein, fat, and fiber that your body needs to function at its best. (Thus, the term “empty calories.”) For good health, try to cut back on your added sugar intake. The U.S. Dietary Guidelines for Americans recommends limiting calories from added sugar to 10 percent or less of your daily calories. So, for example, if you eat 2,000 calories a day, you’d budget 200 calories max for added sugar (or no more than 50 grams of added sugar a day). It pays to read food labels: The sugar content in a 16-ounce soda is around 64 grams (or 16 teaspoons) and has 240 calories. One soda could account for a lot more than your daily sugar intake!

Sugar activates the “reward center” in your brain, similar to how an addictive drug acts. When you eat sugar, your brain releases dopamine, a feel-good hormone that makes you crave more...and more and more. You can probably imagine how that instant gratification can create a negative cycle of compulsive eating. When your body doesn’t use sugar as energy, it’s stored and turned into fat. The takeaway: Sugary treats (mmm, gelato) here and there—and in moderation—are totally fine. But just know it’s possible to get hooked, so keep tabs on your sweets habit.

You probably know that eating too many foods with added sugars can send your blood sugar through the roof. But did you know that chronically high blood sugar levels may lead to hyperglycemia—too much glucose in your blood—and even type 2 diabetes? Yes, it’s true.

Added sugars are also not your friend when it comes to weight loss, and here’s why: Insulin. Insulin is a hormone that plays a role in telling your cells when to store energy as fat or glucose in the body. Hyperglycemia leads to weight gain through “insulin resistance,” when your cells stop responding properly to insulin and cannot use glucose as energy. Your body makes up for this by making more insulin than it needs. When you have excess insulin and blood sugar in your bloodstream, it signals your body to store that extra sugar as fat.

Your metabolism is in charge of converting what you eat and drink into energy. Table sugar, high-fructose corn syrup, and other caloric sweeteners— found in sweet beverages and processed foods —can carry a high glycemic load (the measure of how rapidly food raises blood sugar). As a result, consuming sugary foods and drinks can overwhelm your body’s ability to process them, wreaking havoc on your metabolism.

The fructose found in sugar makes it difficult for your metabolism to process fats and carbs. Those added sugars also cause oxidative stress and inflammation in your body. Chronic stress and inflammation interrupt your body’s ability to function properly and damage the gut microbiome, which can further damage your metabolism.  

We know that added sugars alone add no nutritional value and may even replace more nutritious foods in your diet. But added sugar has an even more sinister side: It depletes valuable nutrients (stored in your body or from foods you’ve eaten) to help your body process the sugar’s calories as energy. Not cool, sugar.

Ever feel hungry shortly after eating a cookie? Sugar intake affects your appetite control by increasing your hunger hormone ghrelin and decreasing the activation of brain satiety centers. That’s a bad combo when you want to feel satisfied after eating!

As with all things, sugar should be consumed only in moderation. Of course, feel free to celebrate special occasions and enjoy your favorite treats every now and then. But understanding how sugar can impact your weight care journey and long-term health can help inform your decisions. Remember, you are in control—and that’s pretty sweet.