A few months ago, the Journal “Appetite” published a study from the University of Surrey (my neighbours), who tracked sleeping and eating schedules of over 600 people. The study found that the majority of people surveyed had a feeding window of 10-14 hours. This data is in keeping with many prior studies that demonstrate that when it comes to our eating and fasting periods we are FAR OFF from what nature has intended us to do.
Do you know your ideal eating versus non-eating (fasting) window? And why it is important not only for researchers working on a study but for YOUR overall health?
A long time ago, when we didn’t have artificial lights in our house, and far far off the time when digital technology was our best companion in the evening, we felt sleepy at dusk, went to bed at the first signs of darkness (around 9pm) and woke up with sunrise (around 6am). Light was the main influencing factor of how our body felt and behaved when it came to sleep-wakefullness-feeding. Even though we have had artificial lights for a long time now, and since recently digital technology that makes us feel connected or ‘on’ 24-7, our body still operates on the circadian rhythms that were determined for us by evolution.
Melatonin, the hormone of sleep, gets releases when dusk falls, close to 8 pm and reaches its highest peak around 9:30pm. If we were to listen to that signal, we would go to bed around 9:30pm and fall asleep around 10pm to get the best of restorative sleep or what nature has programmed for us.
In reality we often don’t listen to the internal signals our body sends us. We continue working and often eating during the times when our body’s functions responsible for concentration, analysis, memory and digestion have long ‘retired’ to have their deserved rest. But we go against them. To what merit?
In the study from the University of Surrey, the researchers quoted the NHS statistics: 67 percent of men and 60 percent of women in the UK are overweight or obese. This causes more than 11,000 yearly hospital admissions, which are directly related to obesity. Even though the communication of effective lifestyle measures to prevent obesity and diabetes - such as a healthy diet and regular exercise - has been an ongoing process for many years, implementation of this advice across the population is not as fruitful as we would hope. Hence, there are a variety of different-angle measures public health authorities are considering. Time-restricted eating is one such measure.
All of the functions in our body work according to a 24-hour circadian rhythm. Our cell renewal and repair, blood circulation, memory consolidation, energy metabolism, muscle protein synthesis, and nutrient digestion and absorption, and many more - work according to their own circadian clocks.
Overall time of eating matters
The ideal eating window for our digestive system is between 8-12 hours. This means that we need to start and finish eating all of our meals and snacks within 12 hours.
Dr Satchin Panda, Professor at the Salk Institute, California, has been researching the circadian regulation of physiology and metabolism for over 25 years. The evidence from his studies tells us that our digestive system works optimally for about 8-11 hours. The process of digestion, absorption and metabolism of food needs to complete a whole cycle EVERY time we eat, regardless whether it is a small piece of toast or a quarter pounder burger. Even a small bite of food takes our digestive system an hour or two to process fully. After about 10-hours of eating on & off, the gut and metabolic organs will continue to work on the food we’ve given them, however this process will slow down for a variety of reasons. At evening times, the circadian clocks of other organs turn on, as our body prioritises their functions when we are supposed to be restful (remember my mentioning of the times when we didn’t have artificial lights and no digital technology?). Thus in the evening, gastric acid and gut hormones will get produced at a different rate, and digestion slows down, resulting in the sense of indigestion, heartburn or acid reflux.
Dr Panda has tracked eating patterns of both humans and rodents to understand if there’s an eating - fasting window that could be most beneficial for health. Many of his studies show that majority of people eat for the whole duration of 14-16 hours of their wakefulness. Most of us tend to believe we’re eating in a standard 3-meals-a-day pattern, but when eating is tracked with an app, it shows that it is more like a 4.5 meals’ pattern.
Read more
Making fat and breaking fat
15 hours of eating erratically produces an ill effect on both our metabolism and overall health. Our digestive system works in such a way that it cannot make and break up body fat at the same time. Every time we eat, even a small morsel, the fat-making processes are turned on. This makes perfect sense from the point of our evolution. Our body starts making fat when the brain detects food is offered in order to have enough reserves to go through a hunger period. Fat is the primary source of energy when the body is deprived of food for a length of time (starting from a minimum of 3 hours spanning to several days). Using fat reserves the body can survive hunger periods, starvation and use fat for energy in periods of convalescence from an injury.
After we finish eating, the digestive system takes anything between 2 to 6 hours to digest, absorb and metabolise the meal. Only then the fat-burning programme is turned on.
Late evening eating
Late-night eating is a habit for many people. For some it is due to their work schedule, either doing shift work or finishing work late in the evening. At 8-10pm stomach acid production is higher than in the morning and afternoon. This has a direct effect on any food we consume late in the evening. Food that has entered the stomach at night has to sit in a high-acid environment. In addition, gut motility decreases during the evening. Gut motility refers to the process by which food is churned and moved and pushed along the GI tract. In response to a late-night meal, excess acid production, slower motility, decreased swallowing rate, decreased saliva production lead to a number of gastro-intestinal discomforts, such as acid reflux, heartburn, constipation, IBS. Left without attention and change, these can lead to serious GI diseases, including cancers.
Read more here
What about weight control?
The implications of late evening or night eating on metabolism and weight management are striking. Experiments on mice who were fed the same diets in calorific value but were either allowed to eat sporadically or follow their natural circadian rhythms, showed that following erratic eating, mice developed markers for metabolic syndrome diseases: obesity & diabetes. Time-restricted feeding improved nutrient sensor functions, raised energy expenditure and reduced inflammation.
Cell Metabolism study
Studies on people showed very similar results. Timing of eating can change our metabolic rate, can change our gut bacteria and affect inflammatory messengers in the body.
Read more
Putting it into practice?
One of my clients recently decided to follow my advice to try time-restricted eating, as he felt discouraged with continuous weight gain. Due to his work, he ate his dinners often at 8 or 9pm. His sleep was affected by late night eating, he often fell asleep at 1am and woke up at 6:30am.
The plan we devised was to follow a 12-12 or 10-14 eating-fasting window, with the goal to finish all his meals by 8pm. As for his actual diet, i.e. calorie intake, we kept all his previous foods the same, with the addition of adding a wide variety of vegetables at his breakfasts and dinners. He was delighted that he could keep eating bagels at breakfast and red meat at dinner time. He lost 7kg in just under 10 weeks’ time!
What do you think of time-restricted eating? Is it something you’re willing to give a go?
Do you know your ideal eating versus non-eating (fasting) window? And why it is important not only for researchers working on a study but for YOUR overall health?
A long time ago, when we didn’t have artificial lights in our house, and far far off the time when digital technology was our best companion in the evening, we felt sleepy at dusk, went to bed at the first signs of darkness (around 9pm) and woke up with sunrise (around 6am). Light was the main influencing factor of how our body felt and behaved when it came to sleep-wakefullness-feeding. Even though we have had artificial lights for a long time now, and since recently digital technology that makes us feel connected or ‘on’ 24-7, our body still operates on the circadian rhythms that were determined for us by evolution.
Melatonin, the hormone of sleep, gets releases when dusk falls, close to 8 pm and reaches its highest peak around 9:30pm. If we were to listen to that signal, we would go to bed around 9:30pm and fall asleep around 10pm to get the best of restorative sleep or what nature has programmed for us.
In reality we often don’t listen to the internal signals our body sends us. We continue working and often eating during the times when our body’s functions responsible for concentration, analysis, memory and digestion have long ‘retired’ to have their deserved rest. But we go against them. To what merit?
In the study from the University of Surrey, the researchers quoted the NHS statistics: 67 percent of men and 60 percent of women in the UK are overweight or obese. This causes more than 11,000 yearly hospital admissions, which are directly related to obesity. Even though the communication of effective lifestyle measures to prevent obesity and diabetes - such as a healthy diet and regular exercise - has been an ongoing process for many years, implementation of this advice across the population is not as fruitful as we would hope. Hence, there are a variety of different-angle measures public health authorities are considering. Time-restricted eating is one such measure.
All of the functions in our body work according to a 24-hour circadian rhythm. Our cell renewal and repair, blood circulation, memory consolidation, energy metabolism, muscle protein synthesis, and nutrient digestion and absorption, and many more - work according to their own circadian clocks.
Overall time of eating matters
The ideal eating window for our digestive system is between 8-12 hours. This means that we need to start and finish eating all of our meals and snacks within 12 hours.
Dr Satchin Panda, Professor at the Salk Institute, California, has been researching the circadian regulation of physiology and metabolism for over 25 years. The evidence from his studies tells us that our digestive system works optimally for about 8-11 hours. The process of digestion, absorption and metabolism of food needs to complete a whole cycle EVERY time we eat, regardless whether it is a small piece of toast or a quarter pounder burger. Even a small bite of food takes our digestive system an hour or two to process fully. After about 10-hours of eating on & off, the gut and metabolic organs will continue to work on the food we’ve given them, however this process will slow down for a variety of reasons. At evening times, the circadian clocks of other organs turn on, as our body prioritises their functions when we are supposed to be restful (remember my mentioning of the times when we didn’t have artificial lights and no digital technology?). Thus in the evening, gastric acid and gut hormones will get produced at a different rate, and digestion slows down, resulting in the sense of indigestion, heartburn or acid reflux.
Dr Panda has tracked eating patterns of both humans and rodents to understand if there’s an eating - fasting window that could be most beneficial for health. Many of his studies show that majority of people eat for the whole duration of 14-16 hours of their wakefulness. Most of us tend to believe we’re eating in a standard 3-meals-a-day pattern, but when eating is tracked with an app, it shows that it is more like a 4.5 meals’ pattern.
Read more
Making fat and breaking fat
15 hours of eating erratically produces an ill effect on both our metabolism and overall health. Our digestive system works in such a way that it cannot make and break up body fat at the same time. Every time we eat, even a small morsel, the fat-making processes are turned on. This makes perfect sense from the point of our evolution. Our body starts making fat when the brain detects food is offered in order to have enough reserves to go through a hunger period. Fat is the primary source of energy when the body is deprived of food for a length of time (starting from a minimum of 3 hours spanning to several days). Using fat reserves the body can survive hunger periods, starvation and use fat for energy in periods of convalescence from an injury.
After we finish eating, the digestive system takes anything between 2 to 6 hours to digest, absorb and metabolise the meal. Only then the fat-burning programme is turned on.
Late evening eating
Late-night eating is a habit for many people. For some it is due to their work schedule, either doing shift work or finishing work late in the evening. At 8-10pm stomach acid production is higher than in the morning and afternoon. This has a direct effect on any food we consume late in the evening. Food that has entered the stomach at night has to sit in a high-acid environment. In addition, gut motility decreases during the evening. Gut motility refers to the process by which food is churned and moved and pushed along the GI tract. In response to a late-night meal, excess acid production, slower motility, decreased swallowing rate, decreased saliva production lead to a number of gastro-intestinal discomforts, such as acid reflux, heartburn, constipation, IBS. Left without attention and change, these can lead to serious GI diseases, including cancers.
Read more here
What about weight control?
The implications of late evening or night eating on metabolism and weight management are striking. Experiments on mice who were fed the same diets in calorific value but were either allowed to eat sporadically or follow their natural circadian rhythms, showed that following erratic eating, mice developed markers for metabolic syndrome diseases: obesity & diabetes. Time-restricted feeding improved nutrient sensor functions, raised energy expenditure and reduced inflammation.
Cell Metabolism study
Studies on people showed very similar results. Timing of eating can change our metabolic rate, can change our gut bacteria and affect inflammatory messengers in the body.
Read more
Putting it into practice?
One of my clients recently decided to follow my advice to try time-restricted eating, as he felt discouraged with continuous weight gain. Due to his work, he ate his dinners often at 8 or 9pm. His sleep was affected by late night eating, he often fell asleep at 1am and woke up at 6:30am.
The plan we devised was to follow a 12-12 or 10-14 eating-fasting window, with the goal to finish all his meals by 8pm. As for his actual diet, i.e. calorie intake, we kept all his previous foods the same, with the addition of adding a wide variety of vegetables at his breakfasts and dinners. He was delighted that he could keep eating bagels at breakfast and red meat at dinner time. He lost 7kg in just under 10 weeks’ time!
What do you think of time-restricted eating? Is it something you’re willing to give a go?
