People fasting over Ramadan lose an average of 1kg in weight, UAE researchers have found.
Scientists analysed data going back decades to study the impact on body mass during the holy month.
The project involved academics from the University of Sharjah along with colleagues in Bahrain and the UK.
Researchers analysed 85 papers published between 1982 and 2019, covering more than 4,000 people across 25 countries.
“We end up with the conclusion that for all these people there was a small-to-medium effect [on their weight],” said Dr Mo’ez Al Islam Faris, an associate professor of human nutrition at the University of Sharjah and one of the study’s authors.
“This is good to have such a reduction. Any reduction in body weight is good for the health, for the cardiovascular system and general health.”
This year, Ramadan is expected to begin on Thursday, April 23.
Importantly, Dr Faris said weight loss during the holy month was not down to individuals eating less but instead due to changes in how the body metabolises fats when fasting.
Writing in the European Journal of Nutrition, researchers said that fasting, on average, resulted in a 1.022kg weight loss in non-athletic people.
Although modest, the loss is still statistically significant and offers potential health benefits.
The loss was attributed to a reduction in body fat as well as a loss in body fluid.
The team also found that weight loss tended to be greatest when Ramadan fell in summer, when the time between the pre-dawn suhoor meal and the post-sunset iftar meal can be more than 17 hours. People also tend to lose more fluid during the summer as they sweat more in the heat.
In winter, when the fasting time can be around 12 hours, weight loss was least. A person’s sex or age did not have a significant impact on weight gain or loss, the study suggested.
Dr Faris said Ramadan weight loss was in part due to a depletion in the amount of a carbohydrate called glycogen stored in the liver.
If glycogens stores are reduced, the body utilises stored fats as a source of energy by releasing substances called fatty acids into the blood. The liver then takes these fats to use in energy production
“There is no external source of energy, so the body will provide the required energy from its internal energy store,” said Dr Faris.
“This energy store, the very short-term energy store, maybe declines in a few hours. Adipose [fat] tissue is a major source of energy. Body fat stores are a source of energy in fasting from 12 hours up to 15 hours.”
Other analysis by Dr Faris and his colleagues found that fasting reduced waist circumference and blood pressure.
It also increased the level of high-density lipoprotein cholesterol, often referred to as good cholesterol as it cuts the risk of heart problems or stroke.
Additionally, researchers found fasting was linked to a reduction in biochemical indicators of inflammation and oxidative stress, both harmful biochemical changes that can be linked to cancer.
However, Dr Faris, who co-wrote the paper with Dr Haitham Jahrami from the Arabian Gulf University in Manama, Bahrain, said that the effects of Ramadan fasting showed “a wide variation” between studies, and some people put on weight.
This can be partly explained by genetic variation and geographical differences, because the length of fasting depends on the timing of sunset and sunrise, which varies with latitude.
People may also put on weight if they eat to excess after breaking the fast.
“They go for a kind of binge eating. In terms of eating through all the night, it’s not healthy and it’s not actually following the guidance of our Prophet Mohammed," Dr Faris said.
“You can get more benefits in keeping modest in your eating behaviour and spending more time in worship and doing good deeds.”
