This post is also available in Dutch .
Ramadan has started again, the annual month of fasting in which Muslims do not eat between sunrise and sunset. Eating only between certain times – and thus not eating for a somewhat longer period – is what we call intermittent fasting. Actually, we fast every night when we sleep and thus do not eat anything. But some people – regardless of Ramadan – want to fast even longer. For example, by not eating early in the evening or not eating breakfast until noon the next day. This means fasting for about 16 hours and only eating during an 8-hour period. This form of intermittent fasting is called “time-restricted feeding” and is a bit like Ramadan but with different times when you are allowed to eat. Intermittent fasting has recently become very popular as a method for losing weight, and a lot of research has been done on it. Therefore, before comparing it to Ramadan, let’s check out this new diet trend.
Intermittent fasting has been found effective for losing weight, especially in people with (pre)type 2 diabetes. In addition to weight loss, studies also report decreased glucose and cholesterol levels. Intermittent fasting seems even more effective for weight loss than a low-calorie diet that allows you to eat all day. Similar results of intermittent fasting have been found in obese 40+ year-olds who were otherwise healthy.
But is fasting also good for your thinking ability, your cognition? Comparing multiple studies on intermittent fasting, we see positive effects on cognitive functions. For example, in the elderly with mild cognitive impairment, although these effects are similar to those of a low-calorie diet. This research shows that weight loss can improve your mental abilities, whether you choose intermittent fasting or simply eat less during the day. However, other studies show that people perform worse on cognitive tasks after fasting, especially on tasks that measure executive functions, the ability that allows us to regulate and control our behavior and attention.
The difference seems to be in the short-term and long-term effects of fasting. In the long term, it can benefit memory and concentration, as you can actually lose weight with a longer period of consecutive time not eating in a day. However, Ramadan lasts only a month, and most scientific studies of intermittent fasting examine a period of at least eight weeks.
Also, the timing of fasting in a day seems to be important. Intermittent fasting studies show that skipping breakfast and fasting between 9 p.m. and 1 p.m. gives a different effect than skipping dinner and fasting between 5 p.m. and 9 a.m. The latter variant is more in line with your own circadian rhythm, or biological clock, where you stop eating when it’s dark and start your day with breakfast. Only this method of fasting lowers blood glucose levels in overweight or obese people, while skipping breakfast and eating later in the evening does not have that effect. Ramadan precisely involves eating only in the dark, which can disrupt the biological clock. This is why people who work shifts also have a higher risk of obesity and type 2 diabetes. However, since Ramadan only lasts one month, this likely is not such a big deal.
Moreover, skipping breakfast is not good for young people’s school performance. A good breakfast – with slow carbohydrates (whole grain cereals, for example) and protein rather than just fast sugars – is important for remembering information and provides an improved attention span. Sunrise is currently around 7:45 a.m., so breakfast should be possible before then. The (small) studies that have been done on cognitive performance during Ramadan show that cognitive functioning was better in the morning but got worse at the end of the afternoon. A factor here is that Ramadan fasting also includes no drinking, and sleep tends to be shorter as well. One study shows that your cognition need not suffer during Ramadan if you remain physically active.
So, fasting for a slightly longer time each day seems to benefit weight control, but whether it is also good for your brain is not yet entirely clear and probably depends on exactly how long and when you fast. Of course, the purpose of the fasting month of Ramadan is not to benefit your weight or brain but to feed your soul to get closer to Allah and also to learn to empathize with people who are having a harder time. Good luck to all!
This is an edited piece from a section out of the (Dutch) book:
Esther Aarts. Waarom we een zak chips altijd in één keer leegeten. Borgerhoff & Lamberigts (2024).
Editor: Lucas Geelen
English Translation: Helena Olraun
Photo by Abdullah Arif on Unsplash
Extra sources:
- https://pubmed.ncbi.nlm.nih.gov/22375233/ Effects of fasting during ramadan month on cognitive function in muslim athletes
- https://pubmed.ncbi.nlm.nih.gov/31109004/ Sleep Patterns, Alertness, Dietary Intake, Muscle Soreness, Fatigue, and Mental Stress Recorded before, during and after Ramadan Observance
- https://pubmed.ncbi.nlm.nih.gov/36438750/ Time-restricted feeding and cognitive function in sedentary and physically active elderly individuals: Ramadan diurnal intermittent fasting as a model
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