Fasting?! What? Why in the world would anyone want to starve themselves, other than for religious reasons? Because it’s good for you, that’s why. Fasting is the planned, controlled absence of eating. Everyone fasts at some point – after all, ‘breakfast’ just means the meal that breaks your fast. Fasting – absence of food – can be done for hours or days, depending on your health goals. Benefits of fasting include reduced insulin resistance, weight loss, increased metabolism, improved levels of growth hormones (which leads to sparing of lean muscle mass), improved mental clarity, and decreased inflammation. It will also make you live longer, according to many well-designed studies looking at fasting and longevity. Fasting has been a pillar of healthy living for centuries, and only fell out of favor when there was a cultural shift towards eating ‘small meals’ every few hours. Frequent eating helps with satiety and prevents dips in blood sugar, but it can wreak havoc on your body’s ability to properly produce and use important hormones like insulin, ghrelin, and growth hormones, leading to obesity, diabetes, chronic inflammation, and other problems.
There are a number of ways to fast, and something called Intermittent Fasting (IF) has become especially popular over the last few years. This type of fasting limits eating to a specific time frame during the day. For example, if someone says they do a 16:8 intermittent fast daily, then what they mean is they limit their eating to 8 hours a day, say from 10 am – 6pm. They don’t eat or drink anything of caloric value from 6pm – 10am in this example. This type of fasting allows you to eat food every day, so you are unlikely to become malnourished or have electrolyte imbalances as a result. And if you’re eating a ketogenic diet, you probably naturally eat in restricted time frames simply because you don’t get hungry very often.
The advantages of this type of fasting are primarily in weight loss. You see, when you eat, your insulin levels rise in response to the food, signaling your body to move the energy you just ate into the cell for use and to store the extra as fat. Frequent eating, or grazing, causes insulin levels to be elevated for longer than they really should be, leading to insulin resistance over time. Think about walking into a room with a bad odor. At first you notice it and it bothers you, but the longer you’re there, the more ‘resistant’ you are to the smell, and eventually you don’t even realize it’s there. The same thing happens with insulin. The more often you eat, the more spikes in insulin your body needs, and the longer your insulin is elevated, the more likely you are to become resistant to it. Insulin resistance leads to diabetes and obesity, among other things. High insulin also promotes fat storage instead of fat burning, making it harder to lose weight, even while restricting calories. Intermittent fasting causes you to have long periods of time for insulin levels to come down, leading to less insulin resistance as well as longer periods in a fat burning stage.
Time frames for Intermittent Fasting can range from person to person. The shortest window should really be 12:12, and 16:8 and 18:6 hour windows are much more common. The longer the fast, the better the benefits. As mentioned above, IF is particularly popular among people who eat a ketogenic diet, but you do not have to be ketogenic to do it. It may be harder on a non-ketogenic diet, but if you do it every day, it will become easier with time, and you will find that your hunger pains will subside with practice.
These include 24-hour, alternate-day, and prolonged (2 or more days – the record is over 300 days, but I definitely don’t recommend that!!) fasts, among others. Longer fasts have a better impact on things like chronic inflammation, diabetes, and longevity. However, these fasts should always be done under the supervision of an experienced professional! While there are numerous benefits to these fasts, it is also very easy to develop electrolyte disturbances, which can be dangerous. If you are diabetic, it can also cause low blood sugar, which can be dangerous as well.
Things to remember while fasting
- Don’t be afraid of water! Water will not have a metabolic effect and will keep you hydrated so you feel better. Add some electrolytes to your water to prevent problems with salt/potassium/magnesium imbalance.
- Start slow. Start with a 12:12 IF and work your way up. You have probably never done this before, and any restricted eating can be quite a change (mentally and physically), so don’t do too much too fast.
- Expect to be hungry at times, even if you are ketogenic. Stay busy, drink water and coffee, and ride it out. Hunger will come and go, and the more often you fast, the easier it will be.
- Eat a diet of whole foods with plenty of vitamins and minerals when you do eat. Fasting will not be helpful for your overall wellness if you still eat crap the rest of the time.
- DON’T fast if you are pregnant, and don’t do any longer fast without supervision, especially if you have chronic health conditions or take medications.
Fasting can be an important part of your health, and I do think that many people will benefit from fitting it into their lifestyle. The ‘guru’ for fasting of all kinds is Jason Fung, MD. If you are interested in learning more, I highly recommend his books or website, which are listed in the resources section here.