“Seventy-four percent of the items in the grocery store contain added sugar,” says Dr. Robert Lustig, a professor emeritus of pediatric endocrinology at the University of California, San Francisco, and author of “Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity and Disease.” So, even if you never stop by the bakery or snack on chocolate bars, it’s likely you’re probably eating more sugar than you realize.
Natural sugar, found in things like fruit and dairy, is accompanied by fiber, which helps slow digestion and prevents blood sugar crashes. Fruit and dairy also offer other essential vitamins and minerals. On the other hand, added sugar provides zero nutritional value and can lead to blood sugar spikes. Moreover, added calories from added sugar can quickly lead to weight gain. “The big sources of added sugar include cakes, cookies, candy and breakfast cereal,” says Lustig. “But there’s also added sugar in yogurt, salad dressing, hamburger buns, hamburger meat, chicken — things you would never associate with sugar.”
The American Heart Association recommends limiting added sugar intake to no more than 9 teaspoons (36 grams) of sugar for men and 6 teaspoons (25 grams) of added sugar for women. This is roughly the amount of sugar found in 9–12 ounces of soda or 12–15 large jelly beans. However, the average American consumes 77 grams of added sugar per day.
Logging your food in an app like MyFitnessPal is a great place to start, since it automatically calculates your sugar intake. You can also use the following signs to gauge whether you’re eating too much sugar:
When you eat or drink something containing sugar, it activates the reward center in your brain, making you want more. The brain adapts to the dopamine (aka feel-good chemicals) released when you consume sugar, “which tells the brain ‘This feels good; I want more,” explains Lustig. The problem is, over time, “you may need more sugar to experience that pleasurable feeling, the same way that you may build a tolerance to alcohol and need to drink more to feel buzzed,” says Samantha Cassetty, MS, RD, a New York City-based registered dietitian nutritionist and co-author of “Sugar Shock: The Hidden Sugar in Your Food.” This can create a vicious cycle that hooks you on sweets and makes you feel like you’re “addicted to sugar.”
Do you often find yourself reaching for a sugary snack to power through a work deadline? When the sugar hits your bloodstream, it first makes your blood-sugar levels spike (giving you a boost of energy). However, since added sugar usually isn’t packaged with satiating nutrients like fiber and protein, it subsequently causes blood sugar levels to drop, which is why you feel that inevitable crash.
“People think sugar gives them energy, but research doesn’t show this at all,” says Cassetty. “In fact, it does the opposite, making you feel less alert and focused and more fatigued.” If you have a sugary breakfast and something sweet with your lunch, your entire day may be a series of spikes and drops, causing you to rely on sugar whenever you feel sleepy.
“If you’re drinking sugary drinks, whether that’s soda or a fancy coffee shop concoction, the sugary calories don’t promote fullness.” says Cassetty. “That leads to a calorie surplus that will promote weight gain.”
Additionally, regularly eating processed foods instead of whole foods like fruits, vegetables, whole grains, nuts, beans and other high-fiber foods can lead to weight gain. “Processed food is high in added sugar (for palatability) and low in fiber (for shelf-life),” says Lustig. This makes it easier to over-consume processed foods, leading to a caloric surplus and bigger waistline.
Many people who regularly eat or drink foods high in added sugar feel hazy, confused or unable to focus on their work. This is known as brain fog. “You feel lethargic and less attentive when consuming lots of sugar,” says Cassetty. “Sometimes, people don’t even realize they’re in a fog until they cut way back on their added sugar consumption. The difference in energy levels can be really noticeable if you go from eating a high-sugar, heavily processed diet to a lower sugar, whole-foods, plant-focused diet.”
Some research suggests people who consume a lot of sugar are more likely to experience depression or bad mood. “Sugar plays a role in the inflammatory process, which is thought to be involved in depression,” says Cassetty. “There’s also an association between the healthfulness of your gut and mood disorders. Bacteria in your gut produce neurotransmitters like serotonin, norepinephrine and dopamine, which are involved in mood regulation. A sugary diet hurts your gut health, which may then have a negative influence on your mood.”
Drinking soda or other sugary beverages like juice and snacking on sweets throughout the day increases your risk of developing tooth decay. “When you eat something with sugar, the bacteria that live in your mouth metabolize the sugar and excrete acid as a byproduct,” says Anne Mary Orr, DDS. “This turns your mouth from a neutral pH of 7 to a more acidic state. Once the pH around your tooth dips below the critical pH of 5.5, the tooth starts to dissolve. Saliva buffers or counteracts this acidity and returns the pH to neutral. In an average person, it takes 20 minutes for your mouth to return to a neutral state.”
Each time you eat or drink something containing sugar, “you reset that 20-minute timer, where your teeth are dissolving over and over,” explains Orr. “Repeated exposure weakens the tooth more.” To protect your teeth, it’s a good idea to cut back on high-sugar foods and beverages. One smart trick: Brushing your teeth after every meal can help deter snacking.
Eating too much sugar can prevent you from having a glowing complexion. “There is compelling evidence showing high-sugar diets contribute to acne and may exacerbate flares,” says Dr. Anna Chacon, a board-certified dermatologist at Cleveland Clinic Florida in Weston and advisory board member for Smart Style Today. However, the impact remains unclear, and more studies are needed, she notes.
Other research shows sugar may make the skin appear saggy or wrinkly. “Collagen [a protein that provides structure to the skin] keeps the skin supple and youthful,” explains Chacon. “Sugar and glucose can produce advanced glycation, meaning a weakening of collagen, which makes the skin appear looser.”
Sleep is crucial for crushing your workouts, promoting recovery and helping with weight-loss. However, research shows diets high in refined sugar are linked to poor-quality sleep.
“[The study showed] someone having high sugar intake in the evening had difficulty falling asleep and did not seem to get the most physically restorative sleep,” says clinical psychologist Michael Breus, PhD, a diplomate of the American Board of Sleep Medicine and a fellow of The American Academy of Sleep Medicine.
Restless sleep caused by sugar consumption can subsequently be part of a vicious cycle — poor sleep may cause your hunger hormone (ghrelin) to spike and your satiety hormone (leptin) to drop, prompting you to consume more sugar when you’re tired. Over time, too little sleep could lead to weight gain.
HOW TO REDUCE YOUR SUGAR INTAKE
Sugar can be hidden under many names, so “it’s important to educate yourself so you can read food labels and understand where sugar is showing up in your life.” To get a sense of how much sugar you’re consuming, try keeping a food journal or using an app like MyFitnessPal.
To cut sugar from your diet, smart small by drinking more water instead of soda, energy drinks and other sweetened beverages, recommends Lustig. Another smart way to quickly reduce your added sugar intake is to focus on cooking more at home. Try a new low-sugar recipe or make meal prep part of your weekly routine.
Creating a bedtime ritual to unwind can also help you prioritize sleep and prevent sugar cravings due to fatigue. If you find you’re hungry close to bedtime, opt for something on the lighter side that’s high in protein, like these RD-approved foods.
Originally published June 2016, updated February 2023
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