Health & Environment

Sun-kissed to Curb Weight and Diabetes, study finds

Moderate amount of sun exposure could curb weight gain and halt the development of diabetes, a study from Australia has found.

The findings showed that regular exposure to 10 minutes of noonday sun could suppress the development of obesity and symptoms of diabetes, including insulin resistance and abnormal fluctuation of glucose level.

Dr Shelley Gorman, the study's lead researcher from Australia Telethon Kids Institute, said the key factor is to get one's skin to generate nitric oxide under sunlight exposure to reduce blood pressure.

The research also found that nitric oxide could also benefit our metabolic systems besides our blood vessels.

Professor Juliana Chan Chung-ngor, founding director of the Hong Kong Institute of Diabetes and Obesity, said nitric oxide could improve blood flow through vessel dilation. It may also help in nutrient provision, waste removal and promote healing inside our bodies through inflammatory responses.

Besides the physical benefits, sunlight also elevates people's mood that is essential in the amount of food intake.

"People who receive more sunlight tend to be happier and would eat less, because stress or sadness could drive people to eat more. We call that comfort eating," said Ms Joanne Chan Yuk-yi, a registered dietician who specialises in weight management and paediatric nutrition.

The theory behind this, according to Ms Chan, is that sunshine could increase serotonin levels in our body. Serotonin helps relay messages between approximately 40 billion brain cells, including parts that control our mood and appetite.

Ms Chan added that seasonal affective disorder (SAD) which typically happens during winter is an example of how the darkening of summer sunshine could affect us psychologically.

However, no clinically approved nitric oxide donors other than hypertension-treating sodium nitroprusside and organic nitrates (which can cause blood pressure reduction and local irritation when applied to the skin) are available for human use at present, said Dr Gorman.

So far the tests were only done for groups of overfed mice that were exposed to ultra-violet light and topical nitric oxide compound cream. Further research is needed to see if the same effect can be reproduced in humans.

Dr Gorman notes of a setback caused by nitric oxide. She warned that the usage of nitric oxide on humans might lower blood pressure and induce serious headache under excessive or prolonged exposure.

Dr Gorman also advised the public to seek advice on sun exposure from cancer councils before carrying out sunlight-related weight-loss plans.

But Professor Chan worries that people bogged down by weight problems expect reaching out to sunlight as a quick fix and would continue indulging in their unhealthy lifestyles after losing weight.

"Disease is really a consequence of complex interplay between people, timing and setting, and it would oversimplify the situation if we just focus on one factor," said Professor Chan.

For unhealthy lifestyles, Professor Chan blames the society.

"We are living in a high risk society with too much food, too much stress and too little exercise. Keeping a balanced lifestyle and being positive and happy are critically important to staying healthy," she said.

Professor Chan said the essence of staying fit is to remember that "We eat to live and not live to eat."

"The point is we need to go back to basics and understand the importance of adhering to certain principles and patterns which are applicable to many aspects of life," said Professor Chan.

And one "basic" Dr Gorman suggested is to regularly exercise outdoors.

"We all may be able to achieve a ‘double-whammy' of the positive benefits of moderate sun exposure and exercise for weight and diabetes control," she said.

 

By Hilary Wu

Edited by Karen Lee 

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