Intermittent fasting (IF) is an eating pattern that cycles between periods of fasting and eating. It is more than a passing health trend—it’s a way to support the way our bodies naturally work. IF has helped many to lose weight, boost energy levels, improve mental clarity, and more. You’re probably thinking, where do I sign up?
In this article, we will break down what intermittent fasting is, cover how it works, discuss some of the ways to do IF, and address whether it’s right for you.
Intermittent Fasting: How It Works
One of the main benefits of IF is improved metabolic flexibility, which has to do with the body’s ability to use carbohydrate and fat for energy. When given a choice between these two fuel sources, the body chooses carbohydrates first because they convert into quick and easy energy. But carbohydrate-based energy is short-lived and a significant amount causes blood sugar levels to quickly rise and fall. When the body gets stuck in the cycle of blood sugar highs and lows, it requires more fuel and craves sugary snacks. This pattern of eating keeps insulin levels elevated and unused carbohydrates are stored as fat.
So when the body stays in this carbohydrate-based state, where we’re prone to frequent snacking and increased fat storage, achieving weight loss can be more difficult.
But when we go for long periods of time without eating, our bodies tap into stored fat for energy. By improving the body’s tendency to use body fat for fuel, we become “fat adapted,” and it can be easier to lose weight. This is how the intermittent fasting lifestyle helps many shed stubborn and unwanted pounds. The fasting periods give our bodies the opportunity to shift from burning food for energy to burning stored fat.
But the benefits don’t end there. When the body burns fat for many hours, it eventually moves into a state called ketosis, where ketone bodies are made and used for energy. Ketone bodies are the byproducts of fat burning, and research shows that higher levels of ketone bodies in the bloodstream can lead to longer-lasting energy, lower blood pressure, better insulin sensitivity, cognitive enhancement, and an improved mood.
There are a number of different ways to do IF. Unicity recommends the 16:8 approach: fast for 16 hours, and eat your meals during an eight-hour eating window. Many intermittent fasters begin eating around noon and start their fast at 8 p.m. If not eating in the mornings is difficult for you, you could adjust your eating window to 10 a.m. to 6 p.m., or whatever works best for you.
Here are a few other popular IF methods:
4-4-12 approach: This IF approach fits most lifestyles. Fast for at least four hours between breakfast and lunch, at least four hours between lunch and dinner, and at least 12 hours between dinner and breakfast (no snacking in between).
Alternate-day fast: Fast for 24 hours once or twice a week. For example, you would begin your fast directly following dinner on one day, and you wouldn’t eat until dinner the next day.
5:2 approach: Consume only 500–600 calories on two non-consecutive days of the week, but eat normally for the other five days.
More Tips on IF
Though none of the various IF methods specify which foods to eat, intermittent fasting works best when combined with a healthy diet and lifestyle.
Exercise is an important part of an IF lifestyle and can help maximize the benefits. However, IF may not be optimal for those working to improve performance or build muscle.
Most people see the best results after 60–90 days, so keep at it!
When to Avoid Intermittent Fasting
Overall, IF seems to be a promising dietary practice for losing weight and supporting overall health, but it may not be the best approach for everyone. Some groups are more likely to experience complications from restrictive eating and should not attempt IF unless under the close supervision of a physician. These groups include the following:
People with advanced diabetes or people taking diabetes medication who need to maintain steady blood sugar levels to stay healthy
People with a history of eating disorders, such as anorexia and bulimia, that could potentially be triggered by restrictive eating practices
Endurance athletes requiring a steady supply of calories and nutrients to train, perform, and recover
Pregnant or breastfeeding women who have increased calorie and nutrition needs that IF likely won’t provide
People with stress disorders or chronically high cortisol levels should also proceed with caution since food restriction can further increase stress and cortisol levels. But it’s also worth mentioning that a documented benefit of IF is decreased insulin resistance, which may be important in mitigating the dangers of chronic stress. Ultimately, more research is needed to understand the long-term impact of IF on hormones and stress regulation.
Many people benefit from intermittent fasting. But if you find yourself in one of the at-risk groups, you don’t have to miss out on the benefits of weight loss, increased energy, and improved focus. You can still experience those benefits by committing to a healthy, well-balanced lifestyle—eat more plants, choose healthy fats and lean animal proteins, drink water, and avoid added sugars and processed foods. Sticking to this kind of diet is what will have the biggest impact on your health.
Tip for Getting Started
If you’re thinking about giving IF a try, it’s a good idea to do some self monitoring. By collecting data on your health, you can better understand how IF affects you. A good place to start is a daily journal to record your fasting times, meal plans, and stress levels. Pay attention to which IF combination works best with your lifestyle and make adjustments as needed.
Ask your doctor for more advice on how to determine if IF is right for you.
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