The general advice for decades has been to eat small meals and snacks throughout the day to maintain blood sugar balance and energy. But it turns out that this advice may not be the best for everyone. In addition to intermittent fasting, time-limited food intake has many health benefits that are supported by research.
What is time-limited food intake?
Time-limited food intake is the practice of eating all your food within an eight to twelve hour window during the day. Researchers at the Regulatory Biology Laboratory at the Salk Institute for Biological Studies have found that fasting (not eating or drinking water for a period of time) can play an important role in staying healthy.
The study also found that the timing of our eating may be more important than the food itself, especially with respect to the circadian rhythm.
The Salk Study
The researchers fed two groups of mice the same high-fat, high-sugar diet. This diet replicated the Standard American Diet (SAD) that many people eat. One group of mice had access to food 24 hours a day. The other group could only eat during an 8-hour window at night (mice are nocturnal).
After 100 days, the group that had access to an all-day, all-night high-fat diet gained weight and developed health problems, including high cholesterol, high blood sugar, liver damage and decreased motor control.
The group that had access to food only for the 8-hour period weighed 28% less than the first group. And although they consumed the same amount of calories from the same type of food, the members of the time-limited feeding group did not develop the same health problems.
The result of the study
Dr. Satchin Panda, the lead author of the study, noted that their research shows that eating on a regular schedule and having regular fasting periods as well can be beneficial. The reason is that digestion genes are more active earlier in the day while cell repair genes are more active at night. So it may be that eating food while the body is ready to handle it can have health benefits.
Eat according to the time against hunger. Intermittent fasting
Many people hear about time-limited food intake and think it sounds a lot like intermittent fasting. The two have similarities, but also differences.
Intermittent fasting is a generic term for any diet that restricts eating to certain times of the day. The time-limited diet is one such diet. But time-limited food intake puts the emphasis on aligning the time you eat with your circadian rhythm. This means that it is important to eat at the same time (and fast at the same time) every day or so.
Unfortunately for shift workers, this is important for scheduled meals and wake-up calls during the day. This is because during the day, the body expects to receive food and is most capable of handling and processing it.
Time-limited eating is a type of intermittent fasting that aims to limit eating to the time of day when your body is best prepared to digest and use food.
Benefits of time-limited food intake
This type of eating style mimics what we believe to be the normal eating habits of our ancestors. These hunter-gatherer societies would not have had access to food 24 hours a day, 7 days a week. They may only have access to a meal twice a day (when prey is out and available to be hunted). And it would be logical that the reproduction of our ancestors' eating habits could have a positive impact on our health. What the researchers found was that time-limited food intake has many health benefits.
Healthy weight
The Salk study mentioned above found that the body continues to store fat when food continues to enter the body. But after a certain number of hours of fasting, the body begins to break down the fat. A time-limited diet reduces fat production and makes better use of it in the body.
But the time we spend eating also helps. Dr. Panda explains in a YouTube video interview with Dr. Rhonda Patrick that in one study, eating breakfast earlier in the day had a huge impact on the weight loss that participants experienced.
The study was controlled for activity, calories/types of food consumed, etc.
Further examination revealed that time-limited dietary intake helps reduce body fat and also helps reduce cholesterol and triglyceride levels.
Healthy blood sugar
It can also be helpful in balancing blood sugar levels. By eating constantly, the liver continues to produce glucose, which raises blood sugar levels. The time-regulated diet and the long fasting period it creates help give the liver a break from glucose production.
In addition, during periods of fasting, glucose helps build molecules that repair damaged cells and produce new DNA. Salk's study found that glucose tolerance and insulin sensitivity were better when food was restricted to a 12-hour window.
A study conducted by the University of California at San Diego found similar results. Over two thousand overweight women were divided into two groups. One group fasted for at least 12 hours at night, while the other group fasted for less time. The group that fasted for at least 12 hours had higher blood glucose levels than those who fasted for shorter periods.
Reduced inflammation
Regulation of blood sugar and use of glucose for cellular repair also helps reduce inflammation. Inflammation causes many chronic diseases, including heart disease,cancer strokes and the Alzheimer's disease. Salk's study found reduced inflammation as well as improved lipid profile and gene expression.
Reduction of metabolic diseases
The Salk researchers continued to investigate the concept of time-limited food intake in another study and found some interesting results. The original study led researchers to believe that diet helps set the circadian rhythm, but the opposite may be true. What they found is that the primary role of the circadian clock may be to tell the animal when to eat and when not to eat. When the circadian clock is disrupted, chronic diseases can occur. This condition may be a side effect of not eating at times when the body is most able to handle food.
The circadian clock naturally weakens with age. This goes hand in hand with an increased risk of metabolic diseases. Researchers believe that creating a strong circadian rhythm, by consciously controlling the times we eat, can help keep these diseases at bay. Considering that metabolic diseases are becoming more and more common today, these results are very interesting!
Healthy liver
Salk's study also found that the body only begins to break down cholesterol into beneficial bile acids during periods of fasting. This degradation helps to cause the metabolism of brown fat. Brown fat is a good fat that can improve health by improving the body's ability to burn white fat, create heat and even regulate blood sugar.
Dr. Panda explains that the liver genes are more sensitive to the act of eating than to light. One study found that mice fed during the day had liver genes turned on and off at that time, while those fed at night had liver genes turned on and off at that time. In other words, it is important to eat during the day so that the liver continues to process food during the day. Fasting at night is important to keep the liver in repair mode at night. For this reason, the study found that eating during the day may help protect against age-related mild fatty liver.
Precautions on time-limited food intake
The benefits of a time-limited diet are vast, but it may not be right for everyone. People with blood sugar problems or hormonal imbalances may need to get these things under control before trying to eat in a limited time. In addition, the timing (and duration) of fasting can vary from person to person. Talk to your doctor before changing your eating habits and to find out if a time-limited diet is safe for you.
Moreover, it is not a miracle solution. You should always eat healthy foods, no matter when you eat! Although research suggests that limiting food intake to a shorter period of time may help the body adopt a less healthy diet, the Salk study showed that time-limited food intake combined with a healthy diet has the best results.
How do I start the time-limited feeding?
Start by going at least 12 hours overnight without food (or drinks other than water). Research has found health benefits with this time of fasting. After you get used to 12 hours, see how you feel and if you want to try a longer fast. Some research suggests that the longer you fast, the better the health benefits. Some people find that 4 to 6 hours to eat is more convenient for them.
It is not known when, in particular, is the best time to fast. However, it seems that it is important to stick to a regular meal schedule. According to Dr. Panda's research, it makes sense to eat larger, higher-carbohydrate meals earlier in the day when insulin sensitivity is higher. Alternatively, low-carbohydrate meals may be better later in the day.
For some people, it's best to eat dinner early (5-6pm) and not eat again until after breakfast.
For others, it may be easier to delay the first meal in the morning. Remember that any drink that is not water (such as coffee or tea) is considered a meal.
Sources:
The Salk study may offer a drug-free intervention to prevent obesity and diabetes. (North Dakota). Excerpt from https://www.salk.edu/news-release/salk-study-pay-offer-drug-free-intervention-to-prevent-obesity-and-diabetes/
FoundMyFitness. (June 30, 2016). Retrieved January 18, 2019, from address https://www.youtube.com/watch?v=-R-eqJDQ2nU.