A sugar-free diet: is it beneficial for the skin?

The main point to remember.

Most sugar-free diets aim to reduce added and refined sugars, without completely eliminating carbohydrates, which are essential for normal physiological function.
Excessive sugar consumption promotes glycation, a process that stiffens collagen and accelerates skin ageing.
A sugar-rich diet is associated with an increased risk of acne, while a low glycaemic index diet can improve the appearance of the skin.
To date, no solid clinical evidence demonstrates that sugar exacerbates eczema or psoriasis.
Reducing sugar intake does not lead to any deficiencies in the skin: on the contrary, it contributes to better overall skin health.

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Sugar-free diet: what does it involve?

The sugar-free diet is a nutritional approach that aims to reduce, or even eliminate, added and refined sugars, without completely excluding carbohydrates. The latter remain essential to the proper functioning of the body, as they provide the energy required by the brain, muscles and cellular metabolism. The objective of this dietary approach is to return to a more natural, unprocessed diet, rich in nutrients and low in hidden sugars, which are often found in ready meals, flavoured yoghurts and fruit juices.

3%

In clinical studies, a sugar-free diet generally corresponds to an intake of less than 3% of daily calories from sugars.

Generally, three approaches to sugar-free dietary regimens are distinguished:

The strict sugar-free diet, which excludes virtually all carbohydrates, including those from fruits, legumes and cereals. It is rarely adopted outside a medical context.
The so-called “low-carb” diet, which reduces rapidly absorbed and refined sugars while maintaining a moderate proportion of complex carbohydrates sourced from vegetables and wholegrain cereals.
The no-added-sugar diet, the most common approach, which eliminates industrial sugars but retains those naturally occurring in fruits or honey.

According to the recommendations of the World Health Organisation (WHO), free sugars should not exceed 10% of total energy intake in adults and children.

What are the effects of sugar on the skin?

One of the major mechanisms of skin ageing is the accumulation of advanced glycation end-products (AGEs) over time. Glycation is a non-enzymatic reaction in which sugar molecules, such as glucose or fructose, form covalent bonds with proteins, lipids or nucleic acids. AGEs develop both endogenously, through the body’s natural processes, and exogenously, particularly via diet: excessive intake of refined sugars, simple carbohydrates and foods cooked at high temperatures (grilled, fried, roasted) promotes their build-up. Other external factors—such as smoking, alcohol, sedentary lifestyle, pollution or UV exposure—can also stimulate AGE production in the skin.

The collagen and elastin, the principal proteins of the extracellular matrix, are particularly susceptible to glycation. This process results in the formation of cross-links between collagen fibres, which increases their rigidity and sensitivity to stimuli mechanical, while impairing their ability to interact with cells and other extracellular matrix proteins. AGEs also promote oxidative stress and inflammation by increasing the production of free radicals and by activating RAGE receptors (Receptor for Advanced Glycation End Products) on the cell surface, triggering inflammatory cascades that accelerate skin ageing.

Le processus de glycation. — The glycation process.
Source: BILOSHYTSKA A. & al. Skin aging – The role of nutrition and sugar. Journal of Education, Health and Sport (2025).

Glycation often increases after 35 years of age and accelerates with intrinsic ageing. The most common AGEs in the skin are carboxymethyllysine and pentosidine, as well as derivatives such as glyoxal, glucosepane and the methylglyoxal-lysine dimer. Excess sugars and repeated glycaemic peaks promote the formation of these pro-inflammatory molecules, which lead to structural, morphological and functional alterations in skin tissue.

Several studies have investigated the effects of sugar on the skin. A study involving 4,025 women aged 40 to 74 evaluated the impact of diet on skin appearance and signs of skin ageing. The results highlighted a direct link between carbohydrate intake and skin appearance. An increase in carbohydrates in the daily diet was associated with a greater likelihood of wrinkled skin and skin atrophy. These associations were independent of factors such as age, body mass index, sun exposure or physical activity. Conversely, higher intakes of vitamin C and linoleic acid were associated with better skin appearance, with reductions in wrinkles and skin dryness.

A sugar-free diet thus appears to contribute to delaying the onset of skin ageing signs.

1.36

times greater risk of developing wrinkles when adding 50 g of carbohydrates to one’s daily diet.

1.33

times more likely to develop skin atrophy when 50 g of carbohydrates are added to one’s daily diet.

A high intake of sugars and simple carbohydrates is also associated with inflammatory mechanisms in the skin. Increased sugar levels in the body favour the production of free radicals and advanced glycation end-products (AGEs), which activate inflammatory pathways. For this reason, it is sometimes suggested that a low-sugar diet could be beneficial for certain inflammatory dermatoses, such as eczema and psoriasis, by reducing both systemic and cutaneous inflammatory burden.

However, clinical evidence establishing a link between sugar consumption and these inflammatory skin diseases remains limited.

A recent study, conducted on 30 volunteers with atopic dermatitis, assessed the effect of a very low-sugar diet compared with a higher-sugar diet on the progression of eczema. Over three weeks, participants were supported by dietitians and clinical follow-up was carried out using SCORAD (SCOring Atopic Dermatitis), a tool measuring the extent and severity of lesions as well as psychological impact. The results showed no significant difference between the two groups, leading the researchers to conclude that sugar was not an aggravating factor for eczema, at least within the context of this short study.

In contrast, the evidence is more plentiful regarding acne. A study conducted between November 2018 and July 2019 analysed 24,452 adults in order to investigate a potential association between their dietary habits and the condition of their skin. Among them, 11,324 individuals (46%) reported suffering from acne. After adjustment for age, sex, physical activity level, smoking status, daily energy intake and the presence of depressive symptoms, the results showed a significant association between acne and the consumption of high-fat and sugary products and sugar-sweetened beverages.

A high intake of sugars could therefore increase the risk of acne.

1.54

times greater risk of developing acne in individuals with a high consumption of fatty and sugary foods.

1.18

times more likely to develop acne when consuming large quantities of sugary drinks.

These results were confirmed by dietary interventions specifically targeting the glycaemic load of foods. A study conducted on 43 young men with acne compared the effects of a low glycaemic load diet with a “standard” diet (42% higher glycaemic intake than the low-load group). Over 12 weeks, researchers assessed the number and severity of acne lesions during monthly visits. At the end of the study, the total lesion count had decreased more in the low glycemic load group (−23.5 ± 3.9) than in the control group (−12.0 ± 3.5). Similar observations were made for inflammatory lesions (−17.0 ± 3.1 in the low glycemic load group versus −7.4 ± 2.5 in the control group).

These findings indicate that a sugar-free diet may help limit, or even reduce, acne.

Évolution du nombre de lésions inflammatoires dans les groupes "régime alimentaire sans sucre" et contrôle. — Evolution of the number of inflammatory lesions in the “sugar-free diet” and control groups.
Source: VARIGOS G. A. & al. A low-glycemic-load diet improves symptoms in acne vulgaris patients: A randomized controlled trial. The American Journal of Clinical Nutrition (2007).

Could a low-sugar diet be detrimental to skin health?

A low-sugar diet poses no risk of deficiency for the skin. To date, no study has demonstrated any detrimental effect on the skin associated with reducing or stopping sugar. On the contrary, reducing simple sugars is often linked to improved skin quality by limiting inflammation and oxidative stress. Thus, eliminating added sugars does not lead to a deficiency in the skin but rather contributes to maintaining balanced skin.