Do sweets really "disrupt" hormones? What happens in the body after eating sugar, how it relates to insulin, hunger hormones, stress, and sleep, and what scientific sources say about it.
There is a lot written online about sugar and hormones, often in very categorical terms. In some places, sugar is called the culprit for all hormonal troubles, while elsewhere, it is promised that a few simple tricks will "balance your hormones." The reality is calmer and much more interesting. Hormones are chemical signals that organs use to communicate with each other, and the so-called hormonal balance is not a single number that you could measure or ruin with one cupcake.
In this article, we rely on documents and research from the World Health Organization (WHO), the European Food Safety Authority (EFSA), and the British National Health Service (NHS). You will find sources at the end of the article, and they are marked with numbers in the text, for example, [1]. If you are interested in sweet cravings, we write about them in more detail in the article "How to reduce sweet cravings?".
What happens after you eat sugar?
During the digestion of carbohydrates, glucose enters the bloodstream. Its levels in the blood are maintained by the pancreas, which produces two main, opposing hormones [1]:
- Insulin. It is produced by the beta cells of the pancreas when blood glucose levels rise, for example, after a meal. Insulin helps muscles and adipose tissue take up glucose from the blood, and the liver store it in the form of glycogen [1].
- Glucagon. It is produced by the alpha cells of the pancreas between meals and during sleep. It stimulates the liver to release stored glucose so that there is no deficiency in the blood [1].
- Gut hormones. After a meal, so-called incretins, GLP-1 and GIP, are released in the gut, which enhance the insulin response [1].
This is a normal process. A healthy person's body returns glucose levels that have risen after a meal back to normal ranges on its own. We explain why some products raise glucose levels faster than others in the article "Blood glucose levels after a meal: what is important to know?".
When do sugar levels become important? Back in a 2010 scientific opinion, the EFSA noted that when sugars account for more than 20–25% of energy intake, it can adversely affect glucose and insulin responses [2].
| Hormone | What it does (simplified) | Source |
|---|---|---|
| Insulin | Helps cells take up glucose from the blood | [1] |
| Glucagon | Stimulates the liver to release glucose between meals | [1] |
| GLP-1 | Enhances insulin response after a meal | [1] |
| Leptin | Appetite-suppressing hormone | [8] |
| Ghrelin | Appetite-stimulating hormone | [8] |
| Cortisol | One of the stress hormones | [7] |
Free sugars: how much is recommended?
When talking about sugar and health, it is important to know which sugar is being discussed. WHO recommendations apply to free sugars. These are sugars that are added to food and drinks by manufacturers, cooks, or ourselves, as well as sugars naturally present in honey, syrups, and fruit juices [3]. These recommendations do not apply to sugars naturally present in fresh fruits, vegetables, and milk [3].
- The WHO strongly recommends that free sugars account for less than 10% of total energy intake [3].
- Reducing to less than 5%, which is approximately 25 g or 6 teaspoons per day, would provide additional health benefits. This is a conditional recommendation because it is based on a smaller number of studies [3].
- In 2022, the EFSA assessed whether it was possible to set a safe upper limit for sugar. No level below which risk would not increase could be determined, so the EFSA recommends consuming as little added and free sugar as possible while maintaining a nutritious diet [4].
- The NHS advises adults to consume no more than 30 g of free sugars per day, and fruit juices and smoothies should be limited to 150 ml per day in total [5].
| Recommendation | Energy portion | Approximately per day | Source |
|---|---|---|---|
| WHO primary recommendation | less than 10% | up to 50 g | [3] |
| WHO conditional recommendation | less than 5% | up to 25 g (approx. 6 tsp) | [3] |
| NHS for adults | not specified | up to 30 g | [5] |
| EFSA | not specified | as little as possible in a nutritious diet | [4] |
What does the EFSA say about sugar and health? In a 2022 opinion, it is noted that sugar consumption is an established cause of dental caries. In observational studies where sugar replaced other nutrients, no link with the chronic metabolic diseases evaluated was found. In controlled trials with intermediate endpoints, added and free sugars were associated with some disorders, but the reliability of the evidence varied: it was rated as moderate for obesity and blood lipid disorders, and low for fatty liver disease and type 2 diabetes [4].
In other words, there is a link, but it is not as simple as often written. We write about what actually happens when you give up sweets in the article "Sugar detox: what actually happens in the body".
Hunger and satiety hormones: ghrelin, leptin, and GLP-1
Ghrelin is often called the hunger hormone because it stimulates appetite, while leptin suppresses appetite [8]. After a meal, ghrelin levels typically decrease. Scientists are interested in whether different sugars affect these signals in the same way.
In a study by Teff and colleagues, 12 normal-weight women ate food of identical energy value for two days, but 30% of their calories came from a drink sweetened with either fructose or glucose [6]. Here is how the results differed:
| Indicator | Fructose day compared to glucose day |
|---|---|
| Post-meal glucose fluctuations | 66% lower |
| Insulin response | 65% lower |
| Leptin levels over 24 hours | 21% lower |
| Post-meal ghrelin reduction | Weaker (ghrelin decreased by about 30% after glucose meals) |
| Blood triglycerides | Increased faster and for longer |
A lower insulin response might seem like an advantage at first glance. However, the authors noted that satiety signals were weaker, and hypothesized that a diet high in fructose could lead to overeating in the long term [6]. This is a short, small study showing a potential mechanism, not a long-term effect.
The practical conclusion is simple: sugary drinks and juices are a source of free sugars that both the WHO and NHS advise limiting [3, 5]. We write about why it is so easy to confuse hunger with the desire for something tasty in the article "Hunger or food craving: how to distinguish them?".
Stress, cortisol, and sweet cravings
In a laboratory study by Epel and colleagues, 59 healthy premenopausal women participated. Each of them performed stress-inducing tasks on one day and attended a quiet control session on another [7].
- Women who reacted more strongly ate more. Those whose cortisol levels increased more during stress consumed more calories on the stress day than those who reacted less. There was no difference on the control day [7].
- More sweet food. Women who reacted more strongly ate more sweet food on both days [7].
- Mood is also important. The more their mood deteriorated during tasks, the more they ate [7].
This does not mean that cravings for sweets are "the fault of hormones" or a sign of weak willpower. The study shows that stress, mood, and eating are connected and that people react to stress differently. If you crave sweets every stressful evening, it is worth having other ways to relax: a walk, a conversation with a loved one, or a short break without a phone.
Sleep, hunger hormones, and the desire for sweet snacks
Sleep is also related to hunger hormones. In a study by Spiegel and colleagues, 12 healthy young men spent only 4 hours in bed for two nights, and 10 hours for two nights in another period [8]. Changes were clearly visible after the short sleep nights:
| Indicator after two nights of short sleep | Change |
|---|---|
| Leptin (suppresses appetite) | 18% less |
| Ghrelin (stimulates appetite) | 28% more |
| Feeling of hunger | 24% stronger |
| Appetite | 23% higher |
| Desire to eat high-calorie, carb-rich food | 33–45% higher |
The study is small and included only men, but it illustrates well why cookies seem especially tempting after a night without enough sleep. If you crave sweets most after short nights, maybe it's worth starting with sleep rather than willpower.
Women's hormones: what's worth knowing
When talking about women's hormones and sugar, polycystic ovary syndrome is most often mentioned. The NHS now calls this condition polyendocrine metabolic ovary syndrome (PMOS), formerly known as PCOS [10].
- The cause is not known exactly. The NHS states that it may be related to hormones like insulin and testosterone not working properly. Hormones and insulin resistance may be tested during diagnosis [10].
- Symptoms can vary. For example, irregular periods or long intervals between them, weight gain, or difficulty losing it. Sometimes there are no symptoms at all [10].
- Risk of some diseases may increase, including type 2 diabetes [10].
In such cases, the NHS advises eating a healthy and balanced diet and regular physical activity, but a doctor determines the diagnosis and treatment [10]. No diet, "hormone-balancing" tea, or food supplement replaces examinations and a doctor's assessment.
Where does fiber come in?
Fiber is often mentioned when talking about sugar, so it is worth distinguishing what the sources say.
- Whole fruit and juice are not the same. The WHO and NHS classify juices as free sugars, whereas naturally occurring sugar in fresh fruit is not [3, 5].
- Recommended amount. The EFSA considers 25 g of fiber per day to be a sufficient amount for normal adult bowel function [2].
- Main sources are food. The EFSA indicates that we get the most fiber from whole grain products, legumes, fruits, vegetables, and potatoes [2].
In practice, this means: choose a whole fruit instead of juice, add vegetables and legumes to your plate, and eat dessert after a nutritious meal, not instead of it. We explain the difference between soluble and insoluble fiber in the article about soluble and insoluble fiber, and write about where to find them in food in our guide "Fiber: what is it and where is it abundant?".
Important: these research data are about sugar, hormones, and nutrition in general. They are not a description of the effects of the fruttberry product and do not replace a doctor's consultation. Fiber supplements are not intended to regulate blood glucose levels or hormonal activity.
Practical habits for every day
You don't need to give up sweets completely. A few simple habits are enough:
| Habit | Why | Advice |
|---|---|---|
| Read labels | Free sugars are found in cookies, sweetened yogurts, breakfast cereals, and soft drinks [5] | Compare several products and choose the one with less sugar |
| Quench thirst with water | Sugary drinks and juices are a source of free sugars [3, 5] | No more than 150 ml of juice and smoothies in total per day, best during a meal [5] |
| Eat a whole fruit | Sugar in fresh fruits is not classified as free sugar [3] | Instead of a glass of juice, eat an apple or a handful of berries |
| Take care of your sleep | Hunger intensified by 24% after two short nights [8] | Try to go to sleep and wake up around the same time |
| Have a plan for busy days | Stress and bad mood are linked to higher food intake [7] | Don't skip lunch and schedule a short walk |
| Eat fiber-rich food | EFSA: 25 g of fiber per day [2] | Vegetables, legumes, and whole grain products every day |
When to see a doctor?
The NHS lists the main symptoms of diabetes and advises seeking urgent medical attention if they occur [9]:
- constant thirst;
- more frequent urination than usual;
- extreme fatigue;
- unexplained weight loss.
Not everyone with diabetes experiences symptoms, so if you have risk factors, it's worth checking even without them [9]. Also see a doctor if your periods have become irregular or long intervals have appeared between them, or if symptoms interfere with your daily life [10].
Fiber for your daily life: fruttberry fiber mix
We created fruttberry out of personal need, as we wanted a fiber mix that was pleasant to drink daily and contained no added sugar. This is a simple way to supplement your daily diet with fiber when you cannot get enough from food.
Ingredients
- Psyllium husk is the base of the mix.
- Inulin from agave is a soluble fiber fermented in the gut.
- Freeze-dried strawberries (12%) and blackcurrants (8%) provide flavor and color from real berries, not from flavoring.
- Glucomannan from konjac tubers is another soluble fiber.
How much fiber in one teaspoon?
There are 77 g of fiber in 100 g of the mix. In an independent study by the KTU Food Institute, 84.4 g of fiber per 100 g was found in a sample of our mix. One teaspoon (5 g) provides about 3.86 g of fiber and only 11 kcal. The mix contains no added sugar, gluten, lactose, or preservatives and is suitable for vegans.
Mix one teaspoon into 200–250 ml of water and drink immediately. Increase the amount gradually, every 3–4 days. Since fiber swells, always drink enough water: if you drink too little liquid, it can clog the throat or esophagus.
If you want to keep a portion on hand at all times, choose 30 portions of 5 g. The 250 g pack is most convenient for home.
All fruttberry dietary fibers in one place.
Frequently asked questions about sugar and hormones
Does sugar disrupt hormonal balance?
When you eat sugar, insulin is released, which is a normal bodily reaction [1]. The EFSA states that it is better to consume as little added and free sugars as possible, as excess intake is linked to certain metabolic markers [4]. However, one dessert will not "disrupt" your hormones.
How much sugar per day is too much?
The WHO recommends that free sugars make up less than 10% of energy, and ideally less than 5%, which is about 25 g per day [3]. The NHS advises no more than 30 g for adults [5].
Does sugar in fruit count, too?
Sugar naturally present in fresh fruit is not classified as free sugar. Sugar in juices, honey, and syrups is classified as such [3, 5].
Why do I crave sweets more after a night of poor sleep?
In a study, after two nights of short sleep, the appetite-suppressing hormone leptin decreased by 18%, the appetite-stimulating hormone ghrelin increased by 28%, and the desire for carbohydrate-rich food increased by 33–45% [8].
Do fiber supplements regulate blood sugar or hormones?
No. Dietary supplements are not intended to regulate glucose levels or hormonal activity. A fiber blend helps supplement your diet with fiber when you are unable to get enough from food. If you are concerned about your glucose levels or hormones, consult your doctor.
Sources
- Röder PV, Wu B, Liu Y, Han W. Pancreatic regulation of glucose homeostasis. Experimental & Molecular Medicine. 2016;48(3):e219.
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on Dietary Reference Values for carbohydrates and dietary fibre. EFSA Journal. 2010;8(3):1462.
- World Health Organization. Guideline: sugars intake for adults and children. Geneva: WHO, 2015.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA). Tolerable upper intake level for dietary sugars. EFSA Journal. 2022;20(2):7074.
- NHS. Sugar: the facts. Reviewed 2026.
- Teff KL, Elliott SS, Tschöp M et al. Dietary fructose reduces circulating insulin and leptin, attenuates postprandial suppression of ghrelin, and increases triglycerides in women. Journal of Clinical Endocrinology and Metabolism. 2004;89(6):2963–2972.
- Epel E, Lapidus R, McEwen B, Brownell K. Stress may add bite to appetite in women: a laboratory study of stress-induced cortisol and eating behavior. Psychoneuroendocrinology. 2001;26(1):37–49.
- Spiegel K, Tasali E, Penev P, Van Cauter E. Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Annals of Internal Medicine. 2004;141(11):846–850.
- NHS. Diabetes. Reviewed 2026.
- NHS. Polyendocrine metabolic ovarian syndrome (PMOS). Reviewed 2026.
The information provided is general in nature and does not replace the consultation of a doctor or nutritionist. Scientific data are provided regarding fiber and nutrition in general and are not a description of the properties of a specific product. If you have chronic illnesses, are taking medication, are pregnant, or are breastfeeding, consult a healthcare professional before starting to use food supplements. A food supplement is not a substitute for a varied and balanced diet.
