What Is Glycaemic Load (GL)?
While the Glycaemic Index measures how fast carbohydrates raise blood sugar, the Glycaemic Load (GL) accounts for both the GI and the amount of carbohydrate in a serving. This makes GL a more practical tool for real-world eating, as it considers portion size and carbohydrate content, which directly influence post-meal glucose levels.
The formula is:
GL = (GI × carbohydrate content per serving in grams) ÷ 100
Low GL foods produce minimal blood sugar spikes, even if their GI is moderate. Conversely, high GL meals can rapidly elevate glucose, triggering glycation and systemic inflammation, both of which affect skin integrity.
Is watermelon too sugary?
Using a watermelon slice, let's run the equation
Watermelon GI = 76
Watermelon GI = 76
Net carbs in a large slice of watermelon = 10.2g
76 x 10.2 / 100 = 7.7 GL
The University of Sydney defines low, medium and Glycemic loads as follows:
Low Glycemic load (low GL): 0 to 10
Medium Glycemic load (med GL): 11 to 19
High Glycemic load (high GL): 20 and over
🍉 As you can say that slice of Watermelon has a low Glycaemic Load
Write your awesome label here.
Hyperglycaemia is known to induce high
rates of protein glycation
High GL Diets and Skin Ageing
Consistently consuming high-GL meals leads to frequent hyperglycaemia, which fuels the formation of AGEs in collagen and elastin. Over time, this accelerates:
High GL diets also exacerbate inflammatory skin conditions, including acne and rosacea, due to insulin and androgen spikes
- Fine lines and wrinkles
- Loss of skin elasticity and firmness
- Dullness and uneven tone
High GL diets also exacerbate inflammatory skin conditions, including acne and rosacea, due to insulin and androgen spikes
Applying GL Knowledge in Practice
Skincare professionals can guide clients by:
- Focusing on Whole Plant Foods - emphasise fruits, vegetables, legumes, and gluten-free grains as daily staples. These whole plant foods naturally fall within the low to medium range on the Glycaemic Index, helping to maintain steady blood sugar levels and reduce the risk of glycation.
- Eat low-fat meals - to keep dietary fat intake low, as excess fat interferes with glucose transport from the bloodstream into the cells. When this process is blocked, blood sugar levels rise, leading to hyperglycaemia, a key trigger for glycation and premature skin ageing.
- Avoid Processed Foods - processed foods are often packed with refined sugars, unhealthy fats, or both, creating a “blood sugar nightmare”. Reducing or eliminating these products helps to stabilise glucose levels, lower AGE formation, and support overall skin and metabolic health.
For example, fruit is the number one beauty food for a reason: high in fibre, high in water content and low to medium on the Glycaemic Index. Focussing on a low-fat plant-based wholefood diet abundance in fruit is a scientifically-valid way to prevent Hyperglycaemia-induced skin disorders and collagen loss
Conclusion
Glycaemic Load translates the concept of GI into practical dietary advice, highlighting the role of portion size and carbohydrate content in skin ageing. By helping clients understand GL, skincare professionals can empower them to make choices that reduce glycation, inflammation and oxidative stress, all key to maintaining youthful, resilient skin.
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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