Fasting is the act of abstaining from ingesting food and drink with calories and/or requires digestion. “Fasting”, especially in this setting, can refer to the metabolic state of an individual. Intermittent fasting then, is the practice of alternating between periods of eating and fasting. Intermittent fasting has been an appealing approach to weight loss for years and with the rise of social media, it’s more popular than it’s ever been. However, just like any other weight loss method, intermittent fasting can be done incorrectly and thus do more harm than good.
The most popular methods of intermittent fasting are listed below:
-Time Restricted Eating (“16/8” or “14/10”): Time restricted eating can be translated to “fasting window”/”eating window”. 16/8 = fast for 16 hours, and eat during an 8 hour window; 14/10 = fast for 14 hours and eat during a 10 hour window. This is an easier method as the majority of the fasting is accomplished during sleep.
-Twice a Week (5:2): 5:2 fasting can be translated to “regular eating days:fasting days”, meaning you’d fast for 2 days of the week and eat normally for 5. In most cases, someone doing this kind of fasting will not fast entirely, rather they would drastically reduce intake on the 2 fasting days.
-Alternate Day: As the “name” implies, someone doing this fasting method would eat normally every other day and the other days would be drastically reduced calorie days. This is very similar to 24 Hour (“eat:stop:eat”) fasting or “meal-to-meal fasting”, where someone would for example, eat breakfast on Monday, and then not eat again until breakfast on Tuesday.
-Circadian Rhythm: This method times meals with the rising and setting of the sun! Breakfast at sunrise, dinner with sunset; no eating after the sun goes down.
The minimum fasting time necessary to see basic benefits (body weight maintenance, energy) is 12-14 hours. Consistent fasting windows of 16 hours will start to show more advanced benefits, many related to the prevention of metabolic disease, which we’ll get into below. If you are looking to begin a fasting protocol of 16+ hours, you are encouraged to consult your doctor and obtain labs.
For the most part, the aforementioned methods are most common; they can be great options for people to get their feet wet if they’re looking to try fasting. Besides the fact that much of the time fasted is spent sleeping, or fasting falls within timeframes during which many people aren’t usually eating, it is recommended that full days of fasting only consist of calorie restriction rather than a hard fast (cool slang term for this type of fasting = “dirty fasting”). Drinking water and no-calorie beverages are encouraged like water, tea (nothing added), black coffee, and bone broth.
There are some great benefits to fasting, especially when done correctly and appropriately (depending on what works for you).
-reduction of overall calorie intake
-improved metabolism – one paper on intermittent fasting stated that “as long as you’re not malnourished or underweight, one of the best ways to improve metabolism is to go without food for some time”.
-boost cognitive function/decrease “brain fog”
-improved control of blood glucose and blood lipid levels, insulin response, cortisol spikes
-improved blood pressure (increased HDL, decreased LDL)
-evidence suggests that some fasting methods are better than others if this is a main
objective; it’s important to consult with your doctor if you suffer from or are at increased
risk for Alzheimer’s, asthma, MS, stroke
-increased in autophagy (“cellular housekeeping”)
-quick biology lesson: autophagy is when cells break down and destroy damaged, old, and abnormal substances. Time-restricted eating/fasting accelerates repairs in the body such
as repairing damaged DNA, increasing the production of antioxidants, and increased/more
There can be some risks to fasting. They’re usually seen at the start of a fasting regimen and are often temporary, but it is still important to be aware of possible physiological responses that don’t seem or feel great. Negative effects include:
More serious negative effects seen with prolonged, incorrect, or inappropriate fasting include:
-cortisol spikes – the best approach is to ease into fasting; jumping right into anything more than 16/8 may cause an increase in cortisol due to sudden stress on the body which will make weight loss efforts much more difficult.
-negative impacts on fertility in women – extreme fasting or sudden (extreme) calorie restriction can cause the body to think that it is preparing or amid famine, and therefore can impact or inhibit menstruation.
*it is very important for women (especially those over 50) to consider the possible impact on hormones and consult with their physician/OBGYN/endocrinologist before fasting
Is Fasting For You?
You might be wondering if fasting is for you. Here is a general guide to who should and shouldn’t try an intermittent fasting or time-restricted eating plan:
Who SHOULD try–> Anyone who is healthy and looking to lose weight, and looking to improve overall health (metabolism, reduce risk of metabolic disease) can give fasting a try if they are interested in seeing how their body reacts.
Who SHOULD NOT try (without consulting their doctor first)–>
-anyone who is unhealthy
-individuals with any chronic disease
-individuals with thyroid issues
-under-nourished or malnourished individuals
-those at risk for eating disorder(s)
-those with obsessive personalities
-individuals with an excessive training regimen
-women who are pregnant or nursing
Foods to Break Your Fast
Now that we’ve figured out if you should consider fasting or not, let’s make sure you’re equipped with the knowledge of the best way to break your fast! The best part of fasting, in my opinion, 😊 Depending on how long you’ve been fasting for, protein and easy to digest carbs will wreak the least amount of havoc on your gastrointestinal system. Some foods to consider:
-leafy greens, cooked veggies, raw fruits
-fish, poultry, eggs
-flaxseed, chia seed
-steel cut oats
Typically, fasting isn’t so long that GI effects should be a concern but in any case, protein + complex carb + fiber (+some nutrient dense fat) is a great combo. This will help to control blood sugar levels and keep insulin from spiking. Some suggestions:
-salad with protein
-whole wheat avocado toast with egg and kimchi
-protein with roast veggies
-egg with avocado + veggies
-protein shake (add-ins: fruit, spinach, silken tofu, natural nut butter)
A larger snack or a small meal is recommended as your first meal post-fast; overeating can make you feel sick and sluggish, and mess with your stomach. It’s important to avoid refined sugars, processed foods and foods that are very high in fat to prevent GI upset… and to keep you on track! Choosing the proper foods to break your fast can have a huge impact on your progress and the sustainability of your fasting program.
*Side-note, incorporate 30 minutes of walking after eating to aid in digestion and lower post-prandial glucose (the glucose levels seen right after eating).
Now you’ve got the 411 on intermittent fasting. Here are some final beginner tips to wrap up!
*Check with your doctor! If you have the slightest concern or doubt, it’s better to be safe than sorry!
*Time your fast and eating periods so that the majority of your fast occurs while you’re winding down for the evening, sleeping, and getting yourself ready for the next day.
*During your eating window, keep it whole, nutritious and delicious so that you can stick with it!
*Stay hydrated with water, teas and broths during fasting periods.
*Be active during your fast.
*Don’t dive in head first – ease yourself into it.
Nicole, M.S. EXNS