The Spooky Side of Sugar

Most of our holidays in America are built around sugar. Birthday cake, Christmas cookies, spiced cider, you name it—a celebration treat is likely a sugary one. On October 31st, we literally send our children out into the night to demand sugar from strangers (while parents indulge on the leftovers). That’s why this year, we’re encouraging you to join us for a group fast on Halloween. Fast through the frightful food environments lurking around every corner, and trade in your sweets for Zero treats…which we’ll be handing out on social media throughout the day. 

Even though we try to make healthy decisions, there’s no denying sugar is part of our national fabric, and there’s a reason for that: biologically we’re wired to want it. Sugar wasn’t so easy to come by when our metabolisms were evolving. Honey didn’t come in cute little bear-shaped jars, it came in hives full of bees! But those who were able to get access to sugar usually had a better chance for survival—high calories for quick energy. We learned to crave it. 

So, realistically, you’re not going to avoid sugar entirely. You’ve got biology and social pressure working against you. But if you keep yourself informed on the SPOOKY side of sugar, at least you’ll know what you’re getting yourself into, and you might think twice before unwrapping that second Snickers on Halloween.

What is Sugar?

What makes a sugar a sugar? Categorically, it’s a carbohydrate. Chemically, there are a few different kinds: simple sugars (one molecule) and compound sugars (two or more simple sugars combined). What we know as “table sugar” or “granulated sugar” is one of these compound sugars, sucrose. It’s a combination of simple sugars fructose and glucose. Lactose, the sugar in milk, is a combination of simple sugars glucose and galactose.

Common Sources

There are tons of sugars found in nature, but in food you’re likely going to find them in just a few common forms:

  • Sucrose: That’s the disaccharide we know as table sugar. It’s naturally present in small amounts in fruits and some vegetables. Mainly, though, this is a processed sugar that you find in baked goods, sweetened ice cream, flavored yogurts, puddings, and fast foods.
  • Fructose: This one’s a simple sugar found naturally in fruits and some vegetables. When combined with glucose, it can be made into sucrose or high fructose corn syrup.
  • High fructose corn syrup: This one’s really sweet, and you’ll find it in a ton of packaged, processed foods. It’s processed from corn starch, and the final mixture is either 55% fructose and 45% glucose/water (HFCS 55) or 42% fructose and 58% glucose/water (HFCS 42). High fructose corn syrup is found in soda, salad dressings, candy, canned fruit, granola bars, condiments, and other processed foods.
  • Hidden sources of sugar: There at least 61 names manufacturers use to describe added sugars on food labels! Common ones include high fructose corn syrup, dextrose, rice syrup, cane juice, cane sugar, glucose, honey, maltodextrin, caramel, fruit juice concentrate, maple syrup, and molasses. An estimated 74% of packaged products contain added sugar.

Natural vs Added Sugar

When referring to the health risks of sugar, the majority of studies refer to added sugars. These are sugars that are added to a food or beverage during processing. Most commonly, these come in the form of sucrose or high fructose corn syrup, but you can also “add” other forms of sugar to food items, like honey, brown rice syrup, and cane sugar. 

Natural sugars, on the other hand, are the same sugars, but they usually come “packaged” in unprocessed foods like whole fruits and vegetables, accompanied by fiber, vitamins, minerals, and antioxidants. So the sugar is still sugar, it just comes with some healthy bonus nutrients. Moderate fructose consumption (emphasis on the moderate!) from these sources in most healthy people is likely fine and does not have the same negative health effects that added sugars do.

How Much Sugar Should You Consume?

Average American Consumption

The average American consumes about 17 tsp (~71 grams) of added sugar per day. By most estimates, that’s way too much. To put that into perspective, one 12 oz. soda has about 11 tsp of added sugar. Americans get 13-14% of their total daily caloric intake from added sugars. The statistics are worse for kids and teens: 16% of their diets are added sugars.

Government Intake Recommendations

The American Heart Association recommends no more than 6 tsp (~25 grams) of added sugar per day for women, no more than 9 tsp (~38 grams) for men. That’s 8-11tsp less than the national average. The 2015-2020 dietary guidelines for Americans recommend that no more than 10% of your total daily calories come from added sugars. So, if you are consuming a 2000 kcal diet, then 200 kcal or ~12 tsp of added sugar would be the recommended limit.

Other Considerations

It’s important to realize that sugar impacts those who are healthy differently than those who already have a chronic disease such as type 2 diabetes, obesity or metabolic syndrome.

In addition, Americans continue to gain weight and metabolic disease is still on the rise, so it’s logical to wonder whether current dietary recommendations are appropriate, or whether we need even stricter guidelines.

Health Consequences of Consuming too Much Sugar

Weight/Fat Gain

Consuming sugar causes a spike in the glucose circulating in your blood. Over time, chronically elevated blood glucose can be pretty dangerous for your health. When blood sugar spikes, the hormone insulin is released, which helps transport the blood sugar into cells to be used as energy. However, when there is excess blood sugar, your body stores sugar to save for later – either as glycogen (in your liver and muscles) or as adipose tissue (“fat”). 

In addition to weight gain from the extra calories, added sugar consumption in excess can specifically promote fat storage through increased levels of insulin. So, limiting total added sugar and preventing sugar from adding too many additional calories to your diet is a great first step toward preventing weight gain.

Poor Energy/Fatigue

We’re all familiar with sugar highs and sugar crashes. 

In one study comparing a meal of pure liquid carbohydrates a calorically equivalent mixture of carbohydrate, fat and protein, the carbohydrate-drinking participants had more feelings of fatigue and had slower reaction times 2 to 4 hours after the meal.

The results were based on subjective perceptions of fatigue, but the energy ups-and-downs can be partially explained by the rise and fall of blood sugar. After a meal, especially one high in carbohydrates, blood sugar levels in the body will rise, giving us an energy boost, but when those levels dip, often too low (after the insulin shuttles it all into your cells), the body will experience fatigue until the blood sugar levels can return back to normal.

Gut Health

What we eat has a direct effect on the system of beneficial (and not-so-beneficial) bacteria in our gut – the so-called “gut microbiome.”  The microbiome is important for nutrient absorption, immunity and overall health. In mice models, refined sugar intake resulted in immune issues and increased potentially harmful bacteria such as C. difficile. Complex carbohydrate intake, on the other hand, including fiber, micronutrients, and prebiotics, promoted the growth of beneficial bacteria and discouraged the abundance of harmful ones.


In order for something to be addictive, it must produce cravings, tolerance and withdrawal. Recent research points to the conclusion that sugar does in fact produce all three of these addictive responses. In those who chronically consume sugar, periods of no sugar can lead to dips in dopamine, which some researchers suggest would be considered the “withdrawal” stage. Dopamine, the main chemical in the “reward” center of the brain, can be replenished with a quick “sugar fix.” 

Another study focusing on obese individuals also showed dysfunction in the dopamine reward circuit with chronic overconsumption of sugar. These individuals had built up a tolerance and needed higher levels of sugar to achieve the same “feel-good” sensation.

Sugar’s addictive qualities aren’t great news for its connection to chronic disease.

Increased Risk of Chronic Disease


Typically, sugar is the body’s primary fuel source. It’s also the main fuel source for abnormal and cancerous cells. In one study, sugar intake correlated with increased tumor burden in mice with liver cancer. In humans, high blood sugar and high insulin levels have been shown to be a risk factor for cancer. High levels of insulin also stimulate growth pathways such as IGF, creating an environment favorable to tumor growth.

One review showed that a high glycemic index diet was related to a slight  increased risk of colorectal cancer and a diet high in glycemic load had increased risk of breast and endometrial cancer. Sugar and highly processed carbs generally contribute to a high glycemic index and a high glycemic load. 

It’s also worth discussing the connection between sugar and the Warburg effect. This is the metabolic adaptation that some cancer cells undergo that makes them highly efficient at generating energy from glucose. Some scientists have posited that reducing sugar intake would thereby reduce their efficiency at creating energy and growing. There have been some preliminary results showing some success with ketogenic diets (low-carb, high fat) as a supplemental treatment for cancer, specifically for those with glioblastomas, prostate, colon, pancreatic, and lung cancer. All this suggests that the removal of sugar and excess carbohydrates may play a role in treatment and/or prevention.

Type 2 Diabetes

Type 2 diabetes is usually an issue of too much insulin. What is the main driver of increased insulin levels? Sugar!

A few short-term, controlled trials suggest that for metabolic changes to occur, fructose and sucrose consumption must be chronic, and they may only occur when you’re consuming more calories than your body needs. We also cannot forget the role that genetics play in our ability to tolerate sugar as well.

But overall, the research isn’t good news for people with a sweet tooth. In a study of healthy adults who consumed 3 or 4 gm per kg fructose per day in addition to their normal caloric intake, there was a 19% or 20% decrease in hepatic insulin sensitivity (not a good sign – we want to maintain insulin sensitivity to avoid diabetes).  A large number of observational studies have also shown a positive association between sugar sweetened beverages and the development of type 2 diabetes. If nothing else – the research clearly tells us to avoid sugary drinks. They seem to be a major culprit in the diabetes epidemic.

Heart Disease

For years, we were taught that saturated fat was the villain when it comes to heart disease, but recent data suggests sugar may have an outsized impact. In one study, when saturated fats were replaced with carbohydrates and added sugars, total cholesterol and triglycerides actually increased, whereas HDL (so-called “good cholesterol) decreased. These unfavorable shifts can increase the risk of heart disease overall. 

Fructose is especially tricky. Unlike other sugars, it needs to be processed by the liver. If you eat a lot of it, fat can accumulate in your liver, leading to an increase in several markers for heart disease.

What Steps Should I Take Now?

Reduce Added Sugar Intake

Obviously health conditions, genetics, and activity level all play a part, but there’s a clear trend in the research: for most people, the less added sugar you consume, the better. Added sugars contain plenty of calories but lack other nutrients our bodies need. So, no matter what diet you’re on, it’s best to consume more nutrient-dense, whole foods and fewer processed items that are likely to contain sugar.

Consume Natural vs Added Sugar

Natural sugars, even though they still are sugars and can have an impact on metabolism, at least come in the form of whole, nutrient-dense foods. They provide additional fiber, vitamins, minerals, antioxidants and other beneficial nutrients to promote a healthy diet. Moderation is still key: when given the choice, opt for less-sugary vegetables instead of sugar-dense fruits.

Fast With Us!

Since every special occasion is likely to be a sugarstravaganza, there will be times you want to opt out, and Halloween may be one of them! We totally understand that social pressure can be a major hurdle to removing sugar from your diet, so we’re here to support you. 

This Halloween, we’ll be doing a not-so-scary group fast with everyone who doesn’t want to chow down on sugar. So head into the app and set a reminder to fast with us on the 31st—your body will thank you, and you might even unlock a spooky in-app surprise. Remember to share your fasting progress and motivate others using #ZeroTreats.

Written by: Nicole Grant and Chad Callaghan

Posted in Health & Science


  • where do I go to set a reminder for fasting tonight? the app wants to start my fast now. thank you for your help. 🙂

    • Hey Robin – Go to your timer screen and select ‘edit reminder’ toward the bottom, you can set it there!

      • I can’t find that at the bottom of my screen. It doesn’t say edit reminders. But I’m fasting anyway. I would like a “surprise ,” but maybe the best one is a little more weight loss. 😊

      • I started my fast over 13 hours ago. Am I still in the fast for the not-so-scary group for Halloween? If not how can I be?

  • I can’t even THINK about sugar anymore!!! My IF journey started in August at 180lbs and a mental mess…today I weigh in at 156 and counting, purely from changing the timing of my eating. Thank you isn’t enough. Mentally, physically, emotionally…I am becoming a new person.

    • What types of fast do you complete I am just starting out and I have completed 36 hrs and 24 for the first week.

      • I do circadian rhythm fasts. I also started my first week with long 36’s and 20:4.

        However it’s nice seeing the scales drop very fast (pun intended), they bounced back up quite quickly when I fueled my body.

        I now reserve myself to a couple long fasts a month and do continuous circadian rhythm.

        This way I can be social with friends on occasion and keep a steady feeding pattern.

        I maintain a on/off day gym routine too, and I’m seeing great routines.

        I tend to keep breads and sweets to a minimum, but also treat myself from time to time.

        Life should continue to be a joy, there’s no good or bad, there’s just too much.


    • Wow!! I started on the 23rd and I am so motivated, have finished two full 36 hour and an 18 Fast but ultimately ADF is perfect for me and I already feel the changes, health wise and appearance. I decided to cut added sugars a week before but this motivates me even more…30 lbs in two months wow. Are you doing alternate day fasting?

      • Hi,

        I’ve done a few long fasts (36hours) and seen great results on the scales early on.
        But that weight comes back on, possibly I do not follow a refeeding process.

        I now stick to a regular routine of circadian rhythm fasts, with a couple longer fasts throughout the month. This has me best balanced and I can maintain social life too.

    • That’s wonderful and motivating for me! Thank you. I started in Sept. at 179 and down to 165. I have 20 to go according to my Cardiologist. He turned me on to fasting.

    • How did you handle cravings? I drink water but sometimes I just want an M&M. The strange thing is that I rarely eat or have sweets in my house. I think it is in my head. But oh do I crave sugar at times.

    • If you go to your timer screen and select ‘edit reminder’ toward the bottom, you can set it there!

  • I’ve been doing IF for 40 days and eating healthy but I am not lossing fat jet, it’s normal? It is possible that IF doesnt work for me?

    • Could be you are eating hidden sugars in your food. If you want to burn fat and go into ketosis you should avoid all processed food with sugar and (if you are very sensitive to sugar) even vegetables like carrots, zucchini and beets.

    • You probably ARE loosing some fat, but first of all you’ll loose excess water in your body. Remember that you need to drink a lot of water and dont give up….dont cheat with some sugar some times….your body will go into survival modus…but if you dont eat carbs you will loose weight if you like it or not 😊👍

    • Don’t expect instant results, changes happen under the hood and in the brain.

      It’s good that you are conscious about your heating rythem, keep at it.

      Ensure you keep your fitness rythem steady too, do a strength or cardio every 2 days.

      Slowly you will see changes in the mirror.

    • To lose fat You need to consume less calories. Make sure You’re eating healthy whole foods (vegetables, fruit, grains) and that You control Your portions. Try to avoid junk food. Also, I suggest counting Your BMR and Your TDEE to know how much calories You should consume daily.
      Fasts work for everyone as they don’t just about fat/weight loss but about the general mindset towards food and many other health benefits. The only reason why You might not be seeing the results You hoped for is that You’re eating incorrectly or possibly consuming calories even while fasting.
      Hope this helps!

    • Track your food everyday. I use the app Lose It! which is very user friendly and free.
      You can see the calories, the macros and the amount of carbs and you can adjust accordingly.
      Also the App Eat this Much, could help you produce a meal plan according to your needs.
      Good luck!

  • This year I bought halloween candy as usual. I’ve had about 3 pieces and it’s all been a disappointment. If I have sugar, it’s going to be the good stuff!

  • I am in England and have been doing the 16 hour fast every day (although I average 18 hours). So far I have lost 21 pounds and have found it the easiest ‘diet’ I have ever done. Thank you so much Zero for finding the willpower I didn’t know I had!

  • Great information! I am a non sugar person but a little Stevia saves the day when I feel like a little Sweet. Thanks for breaking things down so clearly. #ZeroTreats, Zero is my hero. I’ve lost 10 real pounds so far! I’m thankful.

  • A New Halloween Tradition????? That would be Awesome.
    I say we win then day and then set our sights for Thanksgiving!!!

  • The timer screen must be different between android and iPhone. There is no “edit reminder” on my android version. It doesn’t really matter for me because I do time restricted eating every day.

  • Hi all!! Quick question… does diet soda cause an insulin response? I’ve read conflicting information in the web about it. When unable / unwilling to drink coffee (i.e. at night), can a diet soda be a good option to add some flavor instead of water?

    • I’ve read studies that suggest it’s even worse than sugar, because you’re triggering an insulin response when there’s no sugar coming.

      But even putting that aside, why even go there? Be kind to yourself, choose something that you believe will do you good vs something you hope won’t do you harm.

      Think of it this way, you’re not giving anything up. You’re conciously choosing what you put into your body.

  • I don’t have a edit reminder . the last thing on my screen is custom fast. I wonder if i have an older version of zero. 🙁

  • I have been fasting regularly since the beginning of last year. It feels like the perfect antidote to too much food and sugar. It is especially helpful as a tool to avoid sweets today.

  • Recommending 25g of sugar per day?

    That’s basically two pieces of fruit and you’ve hit your sugar limit. Come on guys, that’s totally unrealistic. If I have a banana for breakfast and an apple with lunch, I’m already at 25g sugar. What should I eat for the rest of the day? Let me guess, chicken breast, eggs, cottage cheese, grass-fed beef, etc.

    For people who are NOT on a Keto diet, 25g of sugar per day is not an appropriate recommendation.

    • You don’t have to take the recommendation 😎 do what works for you. Make conscious choices and you’ll do much better than by mindlessly reaching for your default foods.

    • Fruit is full of sugar you are right. It’s the dietary guidelines which tell you to eat 2-5 pieces of fruit a day, which are wrong. They don’t even make a difference between fruit and vegetables !
      Just like the food pyramid that tells you to mostly eat grain, and resulted in the obesity epidemic we now see.

  • We just had an in-depth conversation with our kids about sugar and canceled trick-r-treating. We’re going to stay in, watch a movie, and have family time. Also I’m passing out glow bracelets instead of candy. I can’t in good conscience contribute to the sugar epidemic in our kids.

  • I joined zero fasting last month and have had hard times sticking to food choices due to work loaded but mostly very stressful family problems 😞🤦🏽‍♀️.
    I really need to lose the weight and my body typically responds very slow. I can go days without eating more than 500calories and still won’t lose any pounds. But when that stress gets me, I go for the sweets😥😞.I need help🤦🏽‍♀️😓🥺

  • Hi! I’m new to this app. 🤝 Intermittent fasting has always been a part of my Keto lifestyle but now I’m interested in longer fasts so I thought this app might help to keep track of the time and keep me motivated. I’m starting a 48 hour fast now. 👍

  • On 14 days of 16:8’s. Loving the results so far. No craving and mental clarity are a bonus in my health journey. So glad I found the app. A great resource for accountability 🦋

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