Intermittent Fasting has gained popularity over the last 3-5 years. And it continues to be a hot topic of conversation in both the public and scientific communities. We’ve worked with many patients that have changed their lifestyles to include an intermittent fasting regimen. The most common reason: to achieve weight loss goals.
The definition of fasting is “abstain from all or some kinds of food or drink.” Prior to the recent dietary fad it’s become, fasting has been performed for various religious observances for thousands of years. As it has adapted to modern society, the most common form of intermittent fasting is called 16:8. The numbers refer to 16 hours of fasting and 8 hours of food consumption. Keep in mind that it’s not 8-straight hours of eating! And the food consumed within that 8-hour window must include a healthy and nutrient-dense variety of foods Below is a table that explains the different types of fasting that have been observed over the years.
| Type of fast | Description |
|---|---|
| Complete alternate-day fasting | Involves alternating fasting days (no energy-containing foods or beverages consumed) with eating days (foods and beverages consumed ad libitum) |
| Modified fasting regimens | Allows consumption of 20-25% of energy needs on scheduled fasting days; the basis for the popular 5:2 diet, which involves severe energy restriction for 2 nonconsecutive days per week and ad libitum eating for the other 5 days |
| Time-restricted feeding | Allows ad libitum energy intake within specific time frames, inducing regular, extended fasting intervals; studies of <3 meals per day are indirect examinations of a prolonged daily or nightly fasting period |
| Religious fasting | Variety of fasting regimens undertaken for religious or spiritual purposes |
| Ramadan fasting | A fast from sunrise to sunset during the holy month of Ramadan; the most common dietary practice is to consume one large meal after sunset and one lighter meal before dawn. Thus, the feast and fast periods of Ramadan are approximately 12 hours in length |
| Other religious fasts | Members of the Church of Jesus Christ of Latter-Day Saints routinely abstain from food and drink for extended periods of time. Some Seventh-day Adventists consume their last of two daily meals in the afternoon, resulting in an extended nighttime fasting interval that may be biologically important |
(“Metabolic Effects of Intermittent Fasting” published in Annual Review of Nutrition in 2017)
Multiple scientific studies have been performed to evaluate the health benefits of fasting. It’s important to note that most of these studies have been performed on mice. Why does this matter? Because mice are inherently nocturnal animals… and humans are not. In fact, it has been shown that shift-work can have a significantly negative impact on our natural metabolic rhythms. So there is still a lot to be explored!
However, studies have shown potential health benefits to intermittent fasting, which include:
- Lowering insulin levels between meals, potentially decreasing the likelihood of developing insulin resistance
- Reducing caloric intake, promoting weight-loss
- After 12 hours of fasting, the body breaks down fat for energy
- Improving the body’s resistance to oxidative stress
The greatest impact that intermittent fasting has on our health is related to the reduction of late night snacking. The human body performs much better with eating the majority of calories earlier in the day and less in the evening when there is typically less energy expenditure.
Overall, the following lifestyle modifications recommended with an intermittent fasting lifestyle can have a positive impact on your health:
- Reduced alcohol, sugar, and processed food intake
- Eating a diet rich in vegetables and healthy fats
- Being active throughout the day and building muscle tone
- Avoid nighttime snacking and eating
If you are considering changing your dietary lifestyle, let us help! Dr. Amanda is available Tuesdays and Thursdays for nutritional counseling and guidance to help you find what the best approach is for you. Call today to schedule an appointment!