We have all been there, struggling to lose weight by trying every diet known to man, only to fail and put weight back on. Macronutrient partitioning and nutrient density, along with meal timing all have a role to play in fighting weight gain, but what if we have missed something? For example, longevity and body composition in coastal Mediterranean villages seem to be the best in the world, but why? They eat a diet containing whole grains and other carbs so bang goes the keto theory, they drink red wine, they eat fish and red meat. What I personally believe is the Mediterranean diet should be rephrased to mean the Mediterranean lifestyle. These people out live western populations in the USA, UK and Australia because they follow general principles for longevity. They work outside, they have a sense of community, they are not exposed to a lot of artificial light and their diet is natural and unprocessed. The temperature in the Mediterranean is typically warm all year round with lots of sun exposure, yet melanoma rates are some of the lowest in the world despite excessive sun exposure.
In 2017 a couple of studies were released about sunlight which caught my attention. The first showed that sunlight activated melanopsin in fat cells which consequently reduced fat droplet size in people and raised leptin. Two amazing things should you want to lose weight or prevent excessive fat gain. The second study looked at UV radiation from the sun and weight. The study, conducted on fluffy humans aka mice, showed that UV radiation prevented excessive weight gain. What was most impressive was the results could not be replicated through oral vitamin D supplementation meaning that the weight reduction effects of sunlight were from the UV component.
Various studies on vitamin D and weight have yielded questionable results. However what has been clearer is nitric oxide in the skin which comes from our diets is a more critical pathway in weight control. Nitric oxide (NO) is in the skin only becomes bioactive when exposed to UV radiation.
The study we have mentioned above used UVB radiation. This tells us that just a few minutes of midday sun would be enough to mobilise NO in the skin and for us to benefit from the pending weight reduction effects.
What was more amazing in the results was that UV light reduced fasting glucose levels, insulin and cholesterol in the mice, all markers of metabolic disease.
What can we take away from this? Well UV exposure seems beneficial for reduction in biomarkers for metabolic disease and weight gain. We must also make sure we all experiment ourselves to determine how much midday sun we need to feel the benefits and not place ourselves at risk for skin damage. UV radiation in the right does in incredibly good for health but there are many studies that suggest too much may be detrimental, so make sure you asses your own tolerance levels.