Written By: Kent Hospital Staff on May 3, 2024
What is intermittent fasting?
Intermittent fasting is an eating pattern that cycles between periods of eating and not eating or “fasting.” Most of us do this cycle to some extent naturally, perhaps waiting 10 hours between dinner and breakfast. That’s where the term “breakfast” comes from; it’s the meal that breaks the fast. But the key with intermittent fasting is extending these periods of not eating to take advantage of the body’s unique physiology when in the unfed state.
What are the intermittent fasting methods?
While there are many variations of intermittent fasting, there are three main fasting methods.
- 16/8 Method is the most common method for intermittent fasting. It involves fasting for 16 hours each day and restricting eating to an eight-hour window. That window is often around 11 a.m. to 7 p.m.
- Alternate-Day Fasting is alternating between days of regular eating and days of either very low-calorie intake or complete fasting.
- 12-Hour Fast is a milder form of fasting when individuals try to fast for just 12 hours overnight.
How does intermittent fasting work?
During any of these fasting periods, you can and should drink lots of water to stay hydrated. When eating, insulin levels go up in the bloodstream to help bring sugar into the cells for energy. When insulin levels are high, the body understands now is a good time to store energy in places like fat tissue. During periods of fasting, however, insulin levels become very low, and this allows the body to burn fat stores, so it seems less frequent eating periods allow longer periods when insulin is low, and the body can burn fat.
What are the benefits of intermittent fasting?
Recently, there has been a lot of research and interest in this style of eating for its potential role in weight management as well as overall health. It’s important to note that individual responses can vary. This is not a one-size-fits-all approach and for some, it may be dangerous, however for many years this style of eating was stigmatized, and we now know that for many people it can be safe and quite effective.
Here are six potential benefits of intermittent fasting:
- Weight Loss:
Losing weight hinges on the balance of calories consumed and calories burned. Intermittent fasting may help some people reduce their overall calorie intake by allowing for fewer eating opportunities during which you can eat to a greater sense of fullness.
During the fasting period, particularly after 16 hours, the body can start prioritizing the use of stored fat for energy. Making sure to keep protein intake high and keep up with regular resistance training is key during this eating style to preserve lean muscle mass while losing weight.
- Metabolic Health:
Several studies on intermittent fasting have shown improvements in the body’s sensitivity to insulin and blood sugar levels. When insulin is used more effectively by the body, blood sugar levels can drop. This may be particularly beneficial for those with early insulin resistance issues called “prediabetes.” Although it has also been shown to be effective for people with type 2 diabetes, more medical supervision is necessary as this can be more complicated and can carry more risk - especially depending on the types of medications being used.
- Heart Health:
Some studies suggest intermittent fasting may have positive effects on cardiovascular health by improving blood pressure, cholesterol levels, and other risk factors which may translate to decreased risk of heart disease.
- Brain Health:
Animal studies indicate that intermittent fasting might have neuroprotective effects and support brain health. It may enhance brain function and reduce the risk of neurodegenerative diseases like Alzheimer’s. As I like to remind my patients, if it’s good for the blood vessels, it’s good for the brain.
- Cellular Repair and Longevity:
Fasting has been shown to allow the gut to relax and foster healthier types of bacteria called the microbiome - which may have an anti-inflammatory effect especially when paired with regular exercise and a diet rich in fruits and vegetables.
Fasting also seems to trigger a cellular process called “autophagy.” This complicated process is essentially when damaged cells in the body are cleaned up and removed. Some researchers believe this process may contribute to longevity, and a healthy immune system, and may have anti-cancer properties.
- Simplicity and Flexibility:
Intermittent fasting can be relatively simple to follow, and it doesn't necessarily require specific foods or complicated meal plans. This flexibility may make it easier for some to adhere to compared to other diets. For example, people may find an extra hour of sleep in the morning beneficial as they no longer need to prepare and eat breakfast before work. Or perhaps they may find meal planning for 14 meals/week saves mental energy and time at the grocery store compared to 21 meals/week (the difference of 2 meals/day vs 3 meals/day).
For some people, this may allow intermittent fasting to be a more sustainable eating pattern in the long term compared to traditional calorie-restriction diets - and if a change is sustainable, it is substantially more likely to be effective for that person.
Consult with your doctor:
Regardless of the method, the research shows fasting for at least 12 hours between two meals each day has some health benefits. Prolonged fasting beyond 24 hours notably carries significantly more risk, but even for those attempting a 16/8 style of intermittent fasting, it's important to note that intermittent fasting is not suitable for everyone.
Making gradual, small changes is key. And, before starting any intermittent fasting regimen, it's crucial to consult with a healthcare professional to assess your health status and determine whether this eating pattern is appropriate and if you might benefit from the support of a dietician for detailed guidance.
The long-term impacts of fasting are not well understood at this time, but for many people, short-term benefits are clearer and may be integrated easily into your lifestyle.
Disclaimer: While I am a doctor, I am not your doctor. The content in this blog is for informational and educational purposes only and should not serve as medical advice, consultation, or diagnosis. If you have a medical concern, please consult your healthcare provider, or seek immediate medical treatment.
