Understanding Glycaemic Index (GI)
The Glycaemic Index (GI) is a measure of how quickly carbohydrate-containing foods raise blood glucose levels after consumption. Foods are ranked on a scale from 0 to 100, with pure glucose scoring 100. High-GI foods, such as white bread, pastries, and sugary drinks, cause rapid spikes in blood sugar, while low-GI foods, such as lentils, vegetables, and most fruits, produce a slower, more gradual rise.
For skincare professionals, understanding GI is crucial because blood sugar fluctuations influence skin ageing and inflammation. Rapid spikes in glucose contribute to endogenous glycation, where sugar molecules attach to proteins like collagen and elastin, forming Advanced Glycation End Products (AGEs). These compounds stiffen and weaken the skin’s structural proteins, accelerating fine lines, wrinkles, and sagging.
Don’t be fooled by the appearance of watermelon on this chart; watermelon is actually a skin-healthy food that has a low Glycaemic load that protects against UV ageing and skin cancer. This is why it’s not a good idea to ONLY use GI as the only tool in your dietary toolkit.
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Hyperglycaemia is known to induce high
rates of protein glycation
High-GI Diets and Skin Concerns
High-GI foods don’t just affect metabolic health; they have visible consequences for the skin. Elevated blood glucose triggers insulin surges, which increase sebum production and can exacerbate acne. Moreover, chronic high-GI intake contributes to oxidative stress and inflammation, further degrading collagen and elastin fibres.
Clinical observations have linked high-GI diets to:
Clinical observations have linked high-GI diets to:
- Premature wrinkling and loss of skin elasticity
- Dull, uneven complexion
- Increased susceptibility to inflammatory skin conditions
Incorporating GI Awareness into Skincare Guidance
Skincare professionals can integrate GI knowledge into client consultations to promote holistic skin health. Recommendations include:
- Emphasise low-GI carbohydrates, such as fruits, vegetables and whole gluten-free grains.
- Advise against combining carbohydrates with fats because it prevents glucose transport into the cells, which causes hyperglycaemia.
- Educate clients on how processed and refined foods accelerate glycation and inflammation.
Using GI as a tool, practitioners can help clients maintain stable blood sugar levels, reducing glycation risk and supporting skin repair from within.
Conclusion
Although the Glycaemic Index can be a useful clinical tool, it is also just a tiny facet of everything that makes up a skin-healthy diet. Instead of getting overwhelmed by the numbers and where individual foods sit on the Index, it’s far easier to just design a diet abundant in low-fat, whole plant-foods: fruits, vegetables, legumes and gluten-free grains, because these are always low-medium on the Glycaemic Index
Continue your professional learning.Explore the Skin Nutrition Science Glossary, a growing resource designed for practitioners in aesthetics, nutrition and wellness science.
Article by Star Khechara
Professional agehacker, author, speaker, founder of skin nutrition institute
About me
Ex-skincare formulator and beauty author turned skin-nutrition educator: Star distilled her 20+ years of skin-health knowledge into the world’s first international accredited skin-nutrition school to teach skin therapists, facialists, face yoga practitioners and estheticians how to help their clients feed the skin from within for cellular-level rejuvenation and vibrant beauty.
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