What Happens to Your Body When You Stop Eating Sugar or Do a Sugar Detox?

You may want to skip that 21-day "sugar detox."

There's an unspoken rule in nutrition (and life, in general): If it sounds too good (or easy) to be true, it probably is. And that goes for diet advice, as well.

Information about sugar detoxes abounds on the internet—specifically, on health and wellness websites—claiming that nixing that one ingredient can drastically overhaul your diet. Influencers take you along during their sugar detoxes and then show you their before-and-after photos once they're completely off the stuff (and have seen their sought-after results).

And yes, eating sugar in moderation and as part of a balanced diet is beneficial. But there's one super important detail that not everyone's telling you: It's nearly impossible to stop eating sugar entirely. And much of what you've heard about sugar "detoxes" is possibly wrong. 

Here's what you need to know, according to nutritionists, about what happens when you "stop" eating sugar and why it's not necessarily a foolproof idea.

How Much Sugar Should You Eat Daily?

It's not helpful or accurate to think of sugar as the enemy.

But it also wouldn't be fair to completely dismiss the evidence suggesting that excessive sugar can increase your risk of health conditions. Those health conditions may include heart disease and type 2 diabetes, according to the Centers for Disease Control and Prevention (CDC).

The evidence doesn't suggest that you should cut out sugar completely. The Dietary Guidelines for Americans recommends getting no more than 10% of your daily calories from added sugar. Added sugars are sugars that are put into foods or drinks when they're being processed or prepared. Per the CDC, added sugars include: 

  • Sucrose
  • Dextrose
  • Table sugar
  • Syrups
  • Honey
  • Sugars from concentrated fruit or vegetable juice

Note that those recommended limits don't apply to naturally-occurring sugars, like those in carbohydrates like fruit or milk. 

Also, the Institute of Medicine (IOM) guidelines recommend getting between 45% and 65% of your daily calories from carbohydrates, according to a 2014 study published in Advances in Nutrition. Those calories can be from added sugars and naturally occurring sugars and starches.

You're Still Eating It

It's nearly impossible to cut all sugar out of your diet completely. 

"All carbohydrates break down into sugar once we eat them," Alissa Rumsey, MS, RD, author of Unapologetic Eating and founder of Alissa Rumsey Nutrition and Wellness, told Health. "Our bodies digest and break down the carbohydrates into glucose, a simple sugar, that can be transported throughout the body and brain to provide energy."

To be fair, not all carbohydrates are the same. For instance, various sugar molecules have slightly different molecular structures, while starches are made of several glucose molecules strung together. 

And when you consume carbohydrate-rich foods containing fiber, protein, or fat, your body digests and absorbs glucose more slowly than in foods that are 100% carbohydrates. But still, all carbohydrates are made of sugar molecules that your body breaks down into glucose.

All this to say: When you go on a "sugar detox" and cut out added sugars, high-sugar fruits, and whatever else, you're not actually cutting out sugar. You're still getting it, just in a different form.

But let's say you completely stop eating carbohydrates and get all your calories from protein and fat. Even then, your body would still not be without sugar. Note: Again, if you were to do that, you'd have to cut out plant-based foods entirely, so it's not plausible. 

That's because your body uses a metabolic pathway called gluconeogenesis, according to the National Library of Medicine.

However, that's an oversimplification of very complex biochemistry. Of course, the process of using protein and fat as fuel differs from the default process of using glucose. Still, it's worth noting that your body is never without sugar.

Unclear Sugar Detoxes Rules

Most advocates for "quitting sugar" sidestep all that complexity—that you're never really "off" sugar for good—by making arbitrary rules around what foods are and aren't OK.

"There's no standard for what a 'sugar detox' entails or what foods you must cut out when you say you're going to 'stop eating sugar,'" explained Rumsey. "Some people cut out all sweets or dessert-type foods. Others will cut out sweets and packaged foods that contain sugar, while other people go even more extreme and stop eating most carbohydrates in addition to sweets and packaged foods."

That vagueness is bad because it can be a slippery slope. The lack of an agreed-upon definition of a sugar detox can lead to an increasingly extreme interpretation as time goes on. 

For example, your sugar detox might start as cutting back on sugars, then progress into a more extreme version where you try to avoid carbohydrates altogether.

Is There Such Thing as a Sugar Addiction?

The idea of sugar addiction gets tossed around often. However, it's debatable whether it's possible to be addicted to food. Yes, sugar lights up pleasure centers in your brain as addictive drugs do. But so do other things, like playing with puppies or listening to great music.

A review published in 2016 in the European Journal of Nutrition looked at the existing research on sugar addiction and found that sugar doesn't meet the criteria for being a genuinely addictive substance. But researchers have done most of those studies on rodents.

That's because, while rodents eat sugar when it's available, they don't seek it out when it's paired with an unpleasant stimulus like a shock, which is not the case with addictive drugs. Their tolerance for sugar doesn't seem to increase when they eat it regularly.

Of course, findings from rodent studies don't apply to humans. Still, as of November 2022, there needs to be more human research to form similar conclusions.

A study published in 2018 in Frontiers in Psychiatry concluded that there is strong evidence that sugar can be addictive. But the researchers proposed that food addiction in humans is more like caffeine or nicotine addiction than it is like cocaine or heroin. The researchers described a "subtlety to food addiction" of which most people who meet the criteria may not be aware.

"When people describe feeling 'addicted' to food, what they are usually describing is a mix of intense cravings, a feeling of being out of control around food, and frequent overeating or bingeing on certain highly palatable foods," explained Rumsey. "The experience of being out of control around food is a very real one, and the language of addiction, 'this is a biological drive that I can't control,' fits with this feeling."

When a Sugar Detox Can Hurt

In fact, that feeling is more likely a result of restriction than addiction. 

"When we demonize foods and make them 'off limits,' we tend to increase our desire to have them," Josée Sovinsky, RD, RP, a dietitian and psychotherapist at Blossom Counseling Center, told Health.

Eventually, you'll reach for that off-limits food. You'll feel out of control because you've been denying it for so long and tell yourself that you won't be able to eat it again afterward. 

"This can, at times, explain why people feel addicted to certain types of foods, including sweet foods," added Sovinsky.

But that "withdrawal" you might feel when you give up sugar isn't proof of addiction, nor is it something you should just "power through" for a few days.

"Depending on how people define sugar and the foods they are cutting out, it is quite possible that people are experiencing low blood sugars," said Sovinsky. "Our brain, in particular, requires high amounts of sugar in the form of glucose. When it doesn't get enough, side effects can include headaches, difficulty concentrating, dizziness, irritability, anxiety, and an increase in thoughts about food."

So, you're not detoxing. You're just under-fueled.

An Alternative to Quitting Sugar

Anyone who's heard of intuitive eating is probably familiar with the idea that letting yourself eat what you want can lead to a better relationship with food. Here's why: "Through a process called 'habituation,' the more you allow yourself to consume the foods that feel addictive, the more they tend to lose their excitement," said Sovinsky.

While it's true that you might eat more of these foods than you're used to at first, eventually, they'll lose their luster. Rumsey agreed and even recommended keeping sugary foods in the house instead of banning them, saying that can lessen your desire for them over time.

But you may need more time to be ready to give yourself unconditional permission to eat sugar when you want it. In that case, try to shift your focus from "I have to cut back on sugar" to "I will eat consistently eat filling meals and snacks throughout the day." 

You might feel like you must consciously break your habit of reaching for sugar at a specific time every day. Still, there's a better way to do it than just telling yourself you can't have the sweet treat.

Meals containing all three macronutrients (carbohydrates, protein, and fat) will help dull your cravings for sugar. And having an arsenal of snacks you like—for example, cheese and crackers, avocado toast, hummus with pita, or veggie sticks—means that you always have the option of reaching for something besides a sugary treat between meals.

A Quick Review

The bottom line here is that what happens to your body when you stop eating sugar is that you feel intense and out-of-control cravings for sugar. 

"If you work on adopting a flexible mindset around sugar, as well as eating consistent meals and enough calories and carbohydrates, you will build back trust with your body," said Rumsey. 

That certainly sounds more doable (and better for you) than yet another 21-day "detox."

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