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Improve Cellular Health with Time-Restricted Eating

Purpose: Time-restricted eating may improve metabolism, insulin resistance, weight loss, energy levels, and cellular health.


Time-restricted eating (TRE) involves restricting the amount of time that food is eaten during a 24-hour cycle to between four and twelve hours. For example, if breakfast begins at 9:30am and dinner ends at 6:30pm then eating is restricted to a nine-hour window and fasting occurs for fifteen hours. World-renown longevity researcher, Valter Longo, PhD from the University of Southern California Longevity Institute is a leading researcher on the topic of fasting. Research by Valter Longo, PhD shows that fasting at least twelve hours increases weight loss and improves metabolism and insulin resistance. 


Typically, when fasting occurs for at least twelve hours, the body begins to convert stored fat and dysfunctional cells into energy. By recycling the components of dysfunctional cells, the body is able to repair itself and improve cellular health. Furthermore, fasting for at least twelve hours increases the number of mitochondria within each cell, helping each cell to become more efficient at converting stored fat and food into energy. When each cell is capable of converting stored fat and food into energy more efficiently, then a person may feel that their energy level remains stable throughout the day.


During time-restricted eating, a person can begin eating any time after waking up in the morning, but should finish eating at least three hours before going to sleep. The process of digestion increases blood flow into the digestive system and decreases blood flow in other areas of the body. If a person falls asleep within three hours of eating, then the amount of blood that would normally flow into the brain and other organs will be diminished, leading to less restorative sleep.


Time-restricted eating is the extent of what is necessary for the average person to improve or maintain cellular health. However, Valter Longo, PhD has developed a five-day fasting mimicking diet (FMD) that is shown to have even greater benefits for cellular health. An enhanced level of cellular repair occurs after 48 hours of fasting, which may improve outcomes for people with autoimmune diseases and cancer. The five-day FMD involves eating a vegan diet of 1,100 calories on day one and then between 700 and 800 calories during days 2-5. The benefits from this fasting mimicking diet are similar to a traditional five-day water fast. The advantage of the FMD compared to a five-day water fast is that the body still receives nutrients. During the first day of the FMD, the body begins converting stored fat into energy and starts the process of removing dysfunctional cells. By the end of day two, autophagy begins which is when the body accelerates the removal of dysfunctional cells and uses stem cells to regenerate new cells. During days three, four, and five, the process of autophagy and the conversion of stored fat into energy continues.

Practice: This practice may help someone understand how to improve cellular health with time-restricted eating.

It may be difficult for the average American to fast for at least twelve hours without experiencing a drop in energy levels. About 80% of Americans have some level of insulin resistance which makes the process of converting stored fat into energy inefficient. Functional medicine doctor Steven Gundry, MD recommends fasting one hour longer each day until fasting for at least twelve hours is comfortable.


If attempting a fasting mimicking diet (FMD), start day one by consuming a vegan diet of 1,100 calories and then consume between 700 and 800 calories during days 2-5. The research by Valter Longo, PhD shows that 1,100 calories on day one and between 700 and 800 calories during days 2-5 produces a fasting state and is safe for people with a wide range of weights. Day 6 involves transitioning back to a normal diet by eating lighter food and slightly fewer calories than normal. Valter Longo, PhD recommends speaking with a doctor about the risks, benefits, and frequency of attempting a FMD. A FMD may be done as often as once per month.

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