The Fundamentals of Intermittent Fasting
- 4/20/23
Intermittent fasting is rising in research and growing in popularity. Between the hype and the naysayers, though, what’s the reality around intermittent fasting? Is it healthy or potentially dangerous? Get clear on the pros and cons with these science-backed tips for intermittent fasting.
What is Intermittent Fasting?
When you adopt any new dietary approach, there are a few levers you can pull. To find the best approach for you and your health, you have to look at what you eat, how much you eat, and when you eat. It’s also important to consider how your eating habits make you feel, physically and mentally.
Intermittent fasting is all about changing the timing of your meals.
Types of intermittent fasting vary based on the schedule of your eating. While there are numerous variations, some examples include:
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Alternate day fasting or fasting 1 day per week
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One meal a day (also known as OMAD)
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Intentionally skipping one meal daily
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Eating window (i.e., 14-hour fast with a 10-hour eating window every day)
You might see other names for intermittent fasting: time-restricted eating, cyclic fasting, scheduled eating, and others.
As with any dietary approach, there is no one-size-fits-all. Some people consider intermittent fasting a simple way to reduce their total calories or improve their metabolic flexibility, whereas others might not see much benefit. Despite what other people may be doing, you have to determine whether it’s a strategy that makes a difference for you!
Is Intermittent Fasting Healthy?
Intermittent fasting is studied in research for its potential positive effects on:
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Metabolic flexibility, or your body’s ability to use glucose or fat to fuel your day
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Blood sugar control and heart health
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Potentially preventing chronic conditions, as seen in preliminary studies
Some researchers think a 12-hour eating window is just the baseline for general health. The most moderate approach—the “12-hour eating window”—is hardly considered intermittent fasting at all.
Moderate approaches to intermittent fasting can be effective for some people to reach their health goals. However, more extreme intermittent fasting can toe the line between helpful and harmful.
How Does Intermittent Fasting Work?
Fasting is no magic weight loss bullet nor a cure-all for any and every condition.
Reducing the window in which you eat generally reduces the calories you eat in that period. As long as you aren’t compensating by eating in excess during your meals, then weight loss is a natural product.
Studies show that intermittent fasting works about as well as most other forms of weight loss achieved through changing the way you eat. So, try another way if it doesn't work well for you.
Intermittent fasting gives your body more time to clear out its own energy stores. Over time, this allows your body to burn fat for fuel more effectively. It also lets your body break down damaged tissues and clear the way to build healthier ones, in a process called “autophagy.”
Is Intermittent Fasting Dangerous?
Extended fasting can be life-threatening, but even moderate approaches to intermittent fasting can pose risks for some people. Talk with your healthcare provider before starting any drastic lifestyle change, such as an intermittent fasting routine.
Generally speaking, the more stringent the fasting routine is, the more likely you will encounter issues.
The most common issue for most is the potential to lose muscle. Adopting more moderate approaches that allow you to eat at least once in a 24-hour period can minimize the loss of lean muscle.
Another issue some people run into with more extreme fasting is a rise in stress hormones. Stress hormones like cortisol can raise blood sugar and dysregulate your metabolism, making it harder to achieve your health and fitness goals. This translates into stalled weight loss, or worse, gaining weight in an unhealthy way. Again, more moderate approaches are the way to go if you run into this issue.
How to Make the Most of a Fast
Remember that slow and steady changes are more sustainable than fast ones when weighing the pros and cons of any fasting approach. You don’t want to put the cart before the horse—the fundamentals of a healthy lifestyle still apply here.
Maintaining your exercise routine can help you keep muscle while losing fat during a fast. Choosing more moderate approaches to intermittent fasting can also help ensure you are not starving your muscles.
Breaking a fast is just as important as the fast itself. When you do eat, balance your plate with complete proteins, fiber-full and nutrient-rich veggies, and healthy fats. Intermittent fasting can’t compensate for unhealthy eating!
Start with the most minimal effective fasting routine that you can sustain in a healthy way. There’s no point in adopting something for short-term benefits if it’s not something that you can continue for a long period. Once you find a good routine, you might find that there are other levers to pull or other lifestyle strategies to focus on in order to help you reach your goal.
Avoid backpedaling on your progress and stick to the sensible guidelines for a healthy diet to maximize the benefits you’re looking for while intermittent fasting.
References
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Ulgherait M, Midoun AM, Park SJ, et al. Circadian autophagy drives iTRF-mediated longevity. Nature. 2021;598(7880):353-358. doi:10.1038/s41586-021-03934-0
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Brandhorst S, Longo VD. Fasting and Caloric Restriction in Cancer Prevention and Treatment. Recent Results Cancer Res. 2016;207:241-266. doi:10.1007/978-3-319-42118-6_12
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Harvie M, Howell A. Potential Benefits and Harms of Intermittent Energy Restriction and Intermittent Fasting Amongst Obese, Overweight and Normal Weight Subjects—A Narrative Review of Human and Animal Evidence. Behavioral Sciences. 2017;7(1):4. doi:10.3390/bs7010004
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Horne BD, Muhlestein JB, Anderson JL. Health effects of intermittent fasting: hormesis or harm? A systematic review. The American Journal of Clinical Nutrition. 2015;102(2):464-470. doi:10.3945/ajcn.115.109553
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St-Onge MP, Ard J, Baskin ML, et al. Meal Timing and Frequency: Implications for Cardiovascular Disease Prevention: A Scientific Statement From the American Heart Association. Circulation. 2017;135(9):e96-e121. doi:10.1161/CIR.0000000000000476
