If when you hear the word "fasting", your stomach starts rumbling, we hear you (and we hear it, too!) So why are there so many rumblings about intermittent fasting, and how can it help with weight loss ? As with any diet trend, it’s important to go beyond the headlines and understand how intermittent fasting can impact your health, and if it’s right for you based on your medical history.
Brooke Scheller, Doctor of Clinical Nutrition, gave us some insight into why limiting mealtimes or cutting out food altogether on certain days is becoming so popular. She also gave us a few pointers on where to start if you want to reap the potential health benefits of fasting, like weight loss or increased energy.
What is intermittent fasting?
Intermittent fasting simply means you don’t consume calories for a period of time, or restrict the number of calories you do eat for a period of time.
“The body utilizes many different organs and mechanisms in order to digest food from first bite to elimination, explains Scheller. “The process of digestion itself can take 24 to 72 hours before food is completely removed from the body. When we take a break from eating, we allow these complex systems to also take a break.” If we're constantly eating, we never give them a chance to repair and rejuvenate.
When your digestive system is resting, because you haven’t eaten for a period of time, your body then finds energy from other places—namely your stored body fat. This process is called ketosis (which inspired the keto diet) and it can have some pretty significant health benefits, including cell regeneration and boosting metabolism.
By ceasing to consume high carb and high sugar foods, and shifting into a state of fasting (or ketosis) we also reduce the amount of insulin needed by the body to mitigate high spikes in blood sugar, says Scheller.
What are the benefits of fasting?
At first glance, the main benefit of fasting is eating less, which means less calories consumed and therefore possibly weight lost. However as intermittent fasting is studied more, scientists and researchers have found the benefits go far beyond fitting into your favorite pants.
Scheller’s favorite benefit of intermittent fasting is that it triggers a process in the body called autophagy, which she describes as a rejuvenation of the body at a cellular level. “Autophagy,” she explains, “is a process that can help to recycle old, damaged cells and proteins, and stimulate the growth of new healthy cells in the body." Benefits include anti-aging and anti-cancer properties. This process of autophagy is at the core of many of the benefits of fasting.
Benefits brain cells
Neurodegenerative diseases like Parkinson's or Alzheimer's occur when brain cells are unable to regenerate—the cells then lose function over time and eventually die. Fasting can help allow for that regenerative process. When brain cells are given ample time to heal themselves, the resulting increase of autophagy may have a protective effect. For example, lab testing has shown that starvation in neuronal cell lines can remove toxic molecules and damaged mitochondria from neurons according to a study at The Scripps Research Institute.
Boosts your metabolism
After fasting for 24 or 48 hours your metabolic rate is faster according to a study done at the Queens Medical Center. When we stray away from consuming high carb and high sugar foods, and shift into a state of fasting (or ketosis), we reduce the amount of insulin needed by the body to mitigate high spikes in blood sugar. This allows our body to tap into our own fat cells for energy instead of burning the carbohydrates that we’ve just consumed, which can in turn help you lose excess fat or weight, Scheller explains. The effect intermittent fasting has on our metabolism helps with obesity, insulin resistance, inflammation and hypertension, according to the New England Journal of Medicine.
Inflammation can have all sorts of negative side effects on your health, from low energy to headaches. Researchers in Saudi Arabia found that inflammatory factors were lower in subjects during and after fasting. Fasting also helps to reduce insulin, which is often linked to inflammation and inflammatory diseases.
Types of intermittent fasting
There are multiple ways to get your body into the ketosis state. Some options may be easier than others to incorporate into your routine, so see what works for you.
16/8 Diet (or 8 hour diet)
This is the most common form of intermittent fasting. You eat all meals within the confines of eight hours, and then fast for 16 hours. For some, this means skipping breakfast and then eating lunch and dinner between the hours of 12pm-8pm. Scheller recommends building up to the 16 hour fast starting with 12 hours of no eating (that means no late night snacks!) and upping your fast time from there.
5:2 Diet (or 500 Calorie Diet)
The 5:2 diet is one where you eat normally 5 days a week and restrict calories on the other 2 days a week. Calories are restricted to about 25% of normal intake, Scheller explains, so on a 2,000 calorie diet that means those 2 days are limited to 500 calories a day. This type of fast requires more planning, as calorie counting is a major component.
While juice fasting had a pretty major celebrity following for a while, Scheller explains that you won’t get the same benefits as intermittent fasting. That’s because you’re consuming likely high levels of sugar and even carbs from fruits and veggies in the juice, which will keep your body from going into ketosis.
Intermittent Fasting FAQs
It’s tempting to jump right into a new routine, especially one with many promised benefits, but check with your doctor before you start fasting. Here, Scheller answers some of the most frequently asked questions to guide your intermittent fasting journey:
Can I have soda while fasting?
Scheller recommends avoiding sodas, other sugar sweetened beverages, and high sugar foods particularly while fasting. This is because “when we trigger big peaks and valleys in our blood sugar, it causes us to have more ups and downs in our cravings and appetite,” she explains, “making it more difficult to fast.” We recommend transitioning to seltzers with fresh fruit to flavor it.
Can I have coffee while fasting?
Coffee is fine to have during your fast, but skip the milk or creamer and sugar. To stay in a fasting state you’ll need to stick to under 50 calories for the period of time you're fasting. Eight ounces of coffee with milk and sugar will easily be more than that.
Can I drink water while fasting?
Yes! Stay hydrated everyone. You definitely want to make sure you’re consuming enough water throughout the day, especially while in a fasted state. It will help manage hunger pangs, and will help to flush out waste from your system.
How long should I fast?
To reap the benefits of intermittent fasting, you don’t have to fast every day. Scheller explains you can fast for periods of time 1-3 days per week. If that works for you, you can increase as you begin to get used to fasting to five days per week or even every day.
Does fasting make you cranky?
It sure can! Generally when we experience feelings of being “hangry”, it's due to low blood sugar. This is why it might be helpful to start slow and build up to a longer fast. Also, try to stick with whole, nutrient-dense foods while you’re not fasting to avoid large spikes and drops in blood sugar.
What should I eat when I’m not fasting?
It's best to stick to the general rules of a healthy diet when breaking your fast, according to Scheller. That means including a good source of protein, healthy fats and fiber at every meal. This will help stabilize blood sugar and keep you from those “hangry” moments where you're hungry and craving high sugar or high carb foods for a quick burst of energy.
Is intermittent fasting healthy for everyone?
Always take into account your health history and talk to your doctor before starting a major diet change. It’s important to note particularly that “those with blood sugar irregularities, those with hypo or hyperglycemia, diabetes, or other health conditions should always consult with their physician to see if changes to their diet are right for their unique body chemistry,” says Scheller.
She also tells us that women notoriously have a more difficult time with fasting due to different hormonal patterns, especially for those of us carrying a heavy stress load. In that case, don’t get down on yourself if you function better with a shorter 13 or 14 hour fast. Always remember that every body is different. What works for some might not be best for others.
Freshly delivers healthy, chef-developed meals weekly to make eating well easy and delicious. Check out our rotating menu.