Probably less than social media promises, but more than nothing. If cutting added sugar means you eat fewer calories overall, many people lose a little weight, and your teeth get fewer sugar attacks. Changes in cravings and taste vary a lot from person to person, and the evidence for a quick "sugar detox" is weak.
What counts as added sugar?
The World Health Organization (WHO) uses the term free sugars. That covers:
- sugars added to food and drink by the manufacturer, the cook or you at the table
- sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates
It does not cover the sugars in whole fresh fruit and vegetables, or the natural sugar in milk, because WHO found no evidence of harm from those.
So a month without added sugar, done properly, means no sugar in your coffee, no soft drinks, sweets or most biscuits and cakes, and checking labels on sauces, cereals and yoghurts. It also means honey, date syrup and fruit juice are not a loophole. They count as free sugars too. Fruit itself is fine.
How much sugar do the guidelines allow?
WHO's 2015 guideline makes two recommendations for adults and children:
- Strong recommendation: keep free sugars below 10% of daily energy. On a 2,000 kcal diet, that's about 50 g.
- Conditional recommendation: going below 5%, about 25 g or 6 teaspoons a day, would bring further benefits.
The European Food Safety Authority (EFSA) looked at the same question in 2022 and could not find a level of added or free sugars below which risk stops rising. Its conclusion was that intake should be as low as possible within a nutritionally adequate diet.
Many people pass 25 g without noticing. WHO points out that one tablespoon of ketchup has about 4 g of free sugars and one can of a sugary soft drink can have up to 40 g.
What changes in 30 days?
Your weight, maybe a little. A meta-analysis of randomised trials in the BMJ (Te Morenga and colleagues, 2013) found that when adults cut sugar and ate otherwise as they liked, they lost on average about 0.8 kg. When the sugar was swapped for the same calories from other foods, weight did not change. In other words, sugar affects weight mainly through calories. If you replace biscuits with bread and butter, don't expect the scales to move.
Your teeth. Sugar feeds the mouth bacteria that cause tooth decay. WHO based its guideline partly on the link between free sugars and decay, so fewer sugar hits each day is good news for your teeth.
Your diet as a whole, often. Leaving out soft drinks and sweets frees up room for more filling foods. That's where much of the benefit comes from, and it is the part that lasts if you keep the habit.
Will my cravings and sweet tooth go away?
The evidence here is mixed.
- A small US study (Wise and colleagues, 2016) put people on a low-sugar diet for 3 months. Sweet foods started to taste sweeter to them, but they didn't like sweet foods any less.
- A larger trial from the Netherlands, the Sweet Tooth trial (2026), asked 180 adults to eat a low, regular or high amount of sweet-tasting food for 6 months. There was no difference between the groups in how much they liked sweet taste, how sweet things tasted, or what they chose to eat.
So a month may make sweet things seem a bit sweeter, or it may not. It's unlikely to change your preferences on its own.
As for "sugar withdrawal": a review in the European Journal of Nutrition (Westwater and colleagues, 2016) found little evidence that sugar is addictive in humans in the way drugs are. Missing your usual dessert in the first days is real, but it is more about habit and routine than chemical withdrawal.
What won't happen?
You may read that 30 days without sugar will "detox" your body, clear your skin or transform your energy. We couldn't find good evidence for these claims from short sugar-free periods. Your liver and kidneys clear waste every day, sugar or no sugar. If you feel better, that's great, but it is hard to separate the effect of sugar from better sleep, less alcohol or simply paying more attention to food.
How do I make it work and keep it going?
- Start with drinks. Soft drinks, sweetened iced tea and juices are often the biggest source of free sugars.
- Read the label. Look at "of which sugars" in the nutrition table and at the ingredients list for sugar, glucose syrup, honey and similar names.
- Keep fruit. Whole fruit is not a free sugar and helps with the wish for something sweet.
- Change step by step. Halving the sugar in your coffee for a week before stopping is easier than going cold turkey.
- Think beyond the 30 days. The real aim is a lower level you can keep, not a perfect month followed by a rebound.
If you have diabetes or take medication that lowers blood sugar, talk to your doctor before making big changes to your diet. Changing what you eat can affect your blood sugar and your medication may need checking.
FAQ
Can I eat fruit during 30 days without added sugar?
Yes. WHO's free sugars guideline does not include the sugar in whole fresh fruit. Fruit juice and smoothies, though, count as free sugars.
Are honey or brown sugar allowed?
Not if you want to cut free sugars. WHO counts honey and syrups as free sugars, and brown sugar is still added sugar. Your body handles them in much the same way as white sugar.
Will I lose weight if I stop sugar for a month?
Some people do, mostly because they eat fewer calories overall. In trials where sugar was replaced with the same calories from other foods, weight did not change.
Sources: WHO, Guideline: Sugars intake for adults and children (2015), EFSA, Tolerable upper intake level for dietary sugars (EFSA Journal 2022, 20(2):7074), Te Morenga L et al., Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies, BMJ 2013, 346:e7492, Wise PM et al., Reduced dietary intake of simple sugars alters perceived sweet taste intensity but not perceived pleasantness, American Journal of Clinical Nutrition 2016, 103(1):50, Čad EM et al., The Sweet Tooth Trial: a parallel randomized controlled trial investigating the effects of a 6-month low, regular, or high dietary sweet taste exposure, American Journal of Clinical Nutrition 2026, 123(1):101073, Westwater ML et al., Sugar addiction: the state of the science, European Journal of Nutrition 2016, 55(Suppl 2):55.
