Fasting during the month of Ramadan can be good for your health if it's done correctly.
If you're overweight, it can be an opportunity to lose weight – provided you eat healthily when you break the fast.
The changes that happen in the body during a fast depend on the length of the continuous fast.
The body enters into a fasting state eight hours or so after the last meal, when the gut finishes absorbing nutrients from the food.
In the normal state, body glucose, which is stored in the liver and muscles, is the body's main source of energy.
During a fast, this store of glucose is used up first to provide energy. Later in the fast, once the glucose runs out, fat becomes the next source of energy for the body.
With a prolonged fast of many days or weeks, the body starts using protein and breaking down protein for energy. This is the technical description of what's commonly known as "starvation".
"You are unlikely to reach the starvation stage during Ramadan, because the fast is broken daily," says Dr Razeen Mahroof, a consultant from Oxford.
As the Ramadan fast only lasts from dawn till dusk, the body's energy can be replaced in the pre-dawn and dusk meals.
This provides a gentle transition from using glucose as the main source of energy to using fat, and prevents the breakdown of muscle for protein.
The use of fat for energy helps weight loss. It preserves the muscles and eventually reduces your cholesterol level. In addition, weight loss results in better control of diabetes and reduces blood pressure.
After a few days of the fast, higher levels of endorphins appear in the blood, making you more alert and giving an overall feeling of general mental wellbeing.
A balanced food and fluid intake is important between fasts. The kidneys are very efficient at maintaining the body's water and salts, but these can be lost through sweating.
To prevent muscle breakdown, meals must contain enough energy food, such as carbohydrates and some fat.
The way to approach your diet during fasting is similar to the way you should be eating outside Ramadan.
You should have a balanced diet, with the right .
If you're not careful, food eaten during the pre-dawn and dusk meals can cause some weight gain.
Dr Mahroof recommends approaching the fast with discipline, otherwise an opportunity to lose weight and be healthier could be wasted.
"The underlying message behind Ramadan is self-discipline and self-control," he says. "This shouldn't fall apart at the end of the day."
Those observing the fast should have at least two meals a day: the pre-dawn meal (Suhoor) and a meal at dusk (Iftar).
Dr Mahroof says your food intake should be simple and not differ too much from your normal diet.
It should contain foods from all the major food groups:
Try to limit the amount of sugary foods you eat and instead include healthier sources of carbohydrate in your diet, such as wholegrains, potatoes, vegetables, fruits, legumes, and lower fat dairy products.
Foods high in fibre can help to keep your bowels healthy and add bulk to your meal, helping you to feel full.
It's also worth avoiding caffeine-based drinks such as tea, coffee and cola. Caffeine is a diuretic and stimulates faster water loss through urination.
Suhoor, the pre-dawn meal, should be a wholesome, moderate meal that's filling and provides enough energy for many hours.
"Slow digesting food like pitta bread, salad, cereal (especially oats) or toast provide a constant release of energy," Dr Mahroof says.
"It's important to have some fluids with vitamins, such as fruit juice or fruit. Some people have isotonic drinks to replace any lost salts."
It's customary for Muslims to break the fast (Iftar) with some dates, in accordance with the Prophetic traditions.
Dates will provide a burst of energy. Fruit juices will also have a similar revitalising effect.
Start by drinking plenty of water, which helps rehydration and reduces the chances of overindulgence. Avoid the rich, special dishes that traditionally celebrate the fast.
Carbon monoxide is a poisonous gas that has no smell or taste. When breathed in, it can make you unwell and can kill.
Cooking for large numbers of people using oversized pots on gas stoves has been shown to cause the build-up of carbon monoxide in some homes, particularly those that aren't well ventilated.
If you're planning to cater for large numbers of people at your home – for example, at a pre- or post-Ramadan gathering – it's important that you don't use oversized pots on your gas stove and don't place foil around the burners.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.