Science shows that cutting straight to the heart of every trendy diet may be the key to weight loss — and long-term health.

By Rachael Schultz
Dec 09, 2019 @ 6:00 pm
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Your cube-mate went keto and lost 15 pounds. Your sister-in-law did the Whole30 and felt less moody and less stressed than ever before. Your dad won’t stop raving about how the Mediterranean Diet cleaned up his blood pressure and triglycerides. These diets have more in common than being trendy — they all ask you to cut your sugar down to almost zero.

In the U.S., added sugars make up roughly 17% of most adults’ diet. That makes sense considering roughly 74% of packaged foods have added sugar, according to stats from University of North Carolina, Chapel Hill. And before you think you’re exempt from that category, turn over whatever bottle or box you just munched out of — added sugar is in soda and potato chips, but also Greek yogurt, smoothies, trail mix, and protein bars, says Harley Pasternak, celeb trainer and co-founder of Sweetkick.

And unlike going low-carb or low-fat — both controversial because they force you to cut out foods from your diet that are actually nutritious — reducing your sugar intake is suggested by every health professional worldwide. (Spoiler: It's been tied to weight gain, depression, and increased risk of pretty much every disease.) 

Translation: If you're overwhelmed with trendy diets but thinking about making some diet changes in 2020, sugar is a pretty good place to start. Ahead, everything you need to know about the mental and physical health benefits of a sugar "detox" — plus tips for how to cut sugar out of your diet for good.

PSA: All Sugar Isn’t the Same

All sugars are a type of carbohydrate, but there are two types of sugar molecules: simple and compound.

Simple sugars contain one molecule — glucose, fructose, or galactose — and are the foundation for every type of sweet treat. Because they only contain a single molecule, they break down really quickly, spiking your blood sugar — which is why we often call them “quick-burning fuel.” (More on this category in a minute.)

Compound sugars are made up of two or more of these foundational molecules and encompass things like sucrose, lactose, fiber, and starches. The combination of molecules means your body processes them slightly slower, which is a good thing. But depending on their chemical makeup, they can still be pretty bad for that spike in insulin. Which brings us to...

Glucose vs. Fructose

Considering galactose is almost exclusively found in lactose — i.e. milk products — fructose and glucose are the main simple sugars we are dealing with. And fructose is really the biggest problem, says Kimber Stanhope, Ph.D., R.D, research nutritional biologist with the University of California Davis and the SugarScience team at the University of California San Francisco. (A 2019 study analysis agrees, pointing to fructose above other offending molecules like glucose.)

Okay, quick bio lesson (stay with us — this helps explain pretty much everything else): Glucose and fructose, the two main simple sugars, have the exact same chemical composition. However, they have a different rate-limiting enzyme, which influences how your body responds to the molecule.

Remember, sugar is a carb which means its purpose is to provide fuel for the body. When you eat any sugar, it leaves the intestine and goes directly to the liver. Glucose’s rate-limiting enzyme (called PFK) is very sensitive to how much energy (aka fuel) the liver needs. If the organ is full-up, PFK shuts down and all the glucose bypasses the liver and goes to the brain, the muscles, fat cells, nerve cells — in essence, it allows the rest of the body to use the energy source as fuel.

Fructose, on the other hand, has a rate-limiting enzyme called fructokinase, which doesn’t really care how much energy is already in the liver. That means when fructose leaves the intestines and hits the liver, it stays there. The liver is then stuck dealing with a big overload of the sweet molecule. It stores some as glycogen to later be used as fuel during, say, a workout; but the liver can only store so many carbs or sugars, so whatever fructose is leftover, the liver does what it always does with too much potential energy: It stores the fructose as fat.

That fat has two fates, neither of which are good, Dr. Stanhope says: It’s either sent into the blood along with cholesterol, raising things like triglycerides which directly increases your risk for heart disease; or it’s stored in the liver, increasing liver fat which, among other consequences, can cause insulin resistance, upping your risk for type 2 diabetes. For most people, both happen, increasing their risk for most of the top deadly diseases in America, Dr. Stanhope adds.

The main added sugars we consume are sucrose and high fructose corn syrup (found in sodas, desserts, candies, even salad dressing). Both of these are made up of both glucose and fructose, but the latter is harmful enough to trump the dynamic, meaning these added sugars still contribute to your disease risk, Dr. Stanhope says.

Added vs. Natural

“While it’s important we don’t over-eat sugar of any kind, not all sugar is created equal,” Pasternak says. That is, added sugar is enemy but natural sugars — meaning fruit — are a go.

The sugars in nature’s candy are a mix of sucrose, fructose, and glucose — but there are a handful of reasons you don’t need to stress over the fructose in your fruit, Dr. Stanhope says: For starters, fruits are no more than 10% sugar. And because of that, you’d have to eat a lot of produce to equal the amount of fructose you’d get in, say, a soda — way more than most people are willing to or capable of eating in a day.

Mostly though, fruit’s fiber saves it from being a sugar rush — fiber slows down the rate at which our body processes the accompanying molecules, so your liver and brain aren’t overloaded with sugar but instead are able to process it over a healthier timeline.

What’s more, fruit has a whole lot of other nutrients, namely bioactive compounds like polyphenols, that boost our health and create an advantage that’s above and beyond any potential damage the fructose an do.

In fact, a 2018 meta-analysis in BMJ reports that carbohydrate quality, including sugars, plays a much larger role in disease risk than quantity — that is, things like added sugars and high-glycaemic load grains are more related to obesity, diabetes, cardiovascular disease, and some cancers; whereas whole fruits, non-starchy vegetables, and legumes, help protect against it.

The problem: The food industry has come up with a zillion ways to say "added sugar" on a label, making it hard to know what to steer clear of. (Literally — there are at least 61 different names for sugar listed on food labels.) Look for common terms like brown sugar, corn sweetener, corn syrup, dextrose, fructose, glucose, high-fructose corn syrup, honey, lactose, malt syrup, maltose, molasses, raw sugar, and sucrose.

9 Ways a Sugar "Detox" Can Improve Your Health 

We’re not asking you to cut out added sugar always and forever. “The word cleanse is overused — the body is so resilient it doesn’t really need to be cleansed,” says Pasternak. “But a sugar reset is really about resetting your habits, your palette, and your relationship to sugar.”

Going through a sugar reset will help re-balance your neurochemical and hormonal production and improve pretty much every aspect of your health. And while nixing sweets from your eternal future sounds overwhelming, cutting back for a reset will actually help you crave less of it in the long-term. Here’s nine benefits you can expect from cutting sugar:

It’ll protect your future heart.

Sugar increases your risk for obesity, type 2 diabetes, and pretty much every metabolic disease, but the major risk is to your heart: Researchers from Harvard looked at peoples diet over 15 years and found those who regularly got 17 to 21 percent of their calories from added sugar were 38 percent more likely to die of cardiovascular disease, compared to those who limited added sugar to 8 percent of their calories. In fact, just one or two additional servings of sugar a day increases your risk for coronary heart disease by 10 to 20 percent, reports a 2018 study in Nutrients.

Now, let’s be real: Most of us under 45 aren’t thinking about heart disease. But “the health issues that people encounter later in life are a byproduct of the poor food decisions that they’ve made since they were young,” says Pasternak. And considering heart disease is the leading cause of death for both men and women (most of whom more than likely didn’t think they’d be a statistic when they were young and healthy), this is a huge perk.

You’ll curb your cravings.

People love to say our brain becomes addicted to sugar, and some studies have suggested this — but the research is almost exclusively on mice and our brains are much more complex, says Drew Ramsey, M.D. assistant clinical professor of psychiatry at Columbia University who studies how nutrition affects mood disorders.

But while sugar’s not actually addictive in the official definition of the word, it definitely has a hold on your brain: Eating sweets and carbs prompts our brain to take up more tryptophan which is used to make serotonin, aka the happiness hormone. That’s why your brain craves the sweet stuff, he explains.

“Sugar activates the reward center in your brain, so the more sugar you eat, the more you’re going to want to eat sugar,” he explains. What’s more, a recent study in Obesity revealed that when we eat something that has at least two of fat, sugar, carbs, or salt — so-called “hyper-palatable foods” — our brain’s ability to decipher when we’ve had enough to eat is overpowered, which increases the chances you’ll overeat.

Even if you’re sticking with seemingly healthier sweets like vanilla yogurt or smoothies, eating a lot of sugar cultivates a microbiome that’s hungry for the molecule, which often furthers the craving cycle, Dr. Ramsey adds.

You’ll score more nutrients.

“Eating a diet high in added sugar means you’re inevitably eating less fruits and vegetables, which increases the chances we’re missing out on nutrients key for body and brain health — things like magnesium, zinc, omega 3 fats,” Dr. Ramsey says. One-fifth of deaths world-wide are thanks to poor diets — namely those low in fresh vegetables, seeds and nuts but high in sugar, salt, and trans fat — which breeds disease, reports recent research in The Lancet. Meanwhile, eating more fresh fruits and vegetables is directly linked with weight loss, fending off depression, and higher levels of happiness and life satisfaction.

Your brain will grow and repair more.

“You’re giving birth to thousands of brain cells a day and they’re always in the state of repairing and trying to make new connections, largely thanks to the neurochemical brain-derived neurotrophic factor, or BDNF,” Dr. Ramsey explains.

Added sugars likely suppresses BDNF production, and certain nutrients in whole foods enhance it — so ditching processed foods for real produce means a healthier brain.

It may help ease depression and anxiety.

Men and women who consumed a ton of sugar per day (67+ grams, which is 17 teaspoons of sugar or just under 2 cans of Coke) were more likely to show symptoms of depression over five years than folks who cut back (less than 40 grams a day, or 10 teaspoons), reports a 2017 study in Scientific Reports.

There’s a few things at play here. For starters, not eating enough fruits and vegetables significantly increases your odds for depression, according to a 2017 study in BMC Psychiatry. And that BDNF suppression comes into play, too, since less of the brain-derived neurotrophic factor is directly linked with depression.

The root of all this: What you eat directly affects the bacteria in your gut. “The types of bacteria that live in your colon affect how you feel and think and how anxious you are,” Dr. Ramsey adds. Plants and fermented foods create diversity; sugar creates discontent.

It’ll help your teeth.

The World Health Organization recommends adults and children limit their added sugar intake to max 5% of their overall calories — specifically to protect their oral health, as studies show this is the threshold for developing tooth decay. Bacteria feeds on sugar molecules, so the more it’s in your mouth, the more often bacteria can breed.

You’ll lose body fat.

This may or may not be on your list of 2020 goals, but eating less sugar is directly linked to losing weight, and eating more of it with weight gain, according to a meta-analysis out of New Zealand. Sugar causes spikes in insulin which is our master metabolic switch that then tells your body to store visceral fat, Dr. Ramsey explains. Here’s why that’s important, even if you don’t care about losing weight: Visceral fat not only increases body fat, but it actively produces inflammation, increasing your risk for depression, obesity, and type 2 diabetes, among other issues, he adds.

Your skin will look like magic.

The inflammation sugar creates in the body can exacerbate skin conditions like eczema, acne, and rosacea. Hormones, genetics, and stress can all be culprits too, but docs say giving up sweets can significantly help your skin calm down.

You’ll have a more balanced gut.

“The types of bacteria that live in your colon affect how you feel and think, how anxious you are, whether you gain weight, how hungry you are, what you crave,” Dr. Ramsey says.

When you eat sugar, you’re feeding the less healthy bacteria in your gut and creating inflammation, he explains. “Having an unhealthy microbiome creates an immune system that’s out of whack and a metabolic system that isn’t running as efficiently as it should,” he says. When we eat more plants, diverse fibers, and fermented foods, however, we create a more diverse microbiome.

Ready to get started? Here's how to actually cut sugar out of your diet.