Long fasting is a shock on the body and there are temporary side effects. Don’t be surprised if you experience some of these. Most of them are manageable and all are temporary. They also seem to improve the more often you fast.
- Light-headedness – This can be observed as that low blood-pressure, light-headed feeling that you get when you go from sitting to standing. Most people mistake this for low blood sugar. However, this is almost always salt related. You are not getting enough!
- The acute fix is to make a slurry of salt in a shot glass, and chug it down with some water. Or use LMNT salt packets (which have a mix of sodium, magnesium, potassium). You should feel better in 20 minutes.
- The preemptive fix is to continually have salt throughout the day before it becomes a problem. Almost every liquid you drink should have a pinch of salt in it. Alternatively, you can take 3-4 LMNT packets per day: one immediately upon waking, another when you are working out, and another mid-afternoon. You can take another in the evening, or you can take bouillon instead.
- Hunger during normal meal times – Newbies will definitely feel hungry when they start fasting. It gets better as you get more experienced, but you will still feel a little hungry during your regular meal times. Drink liquids. Try to push through the wave of hunger. Get busy, move around, exercise. If unbearable, try half-scoop or full-scoop of MCT Oil Powder in tea or coffee.
- Dry mouth – You may get that dry mouth feeling. Some of this is caused by not having food which normally stimulates saliva. Sometimes you are not drinking enough water. Sometimes, you are over caffeinated and are overstimulated which causes dry mouth. Also, watch out for keto breath. When your body is running off ketones (instead of glucose), the air you breathe out has a slightly different composition (more ketones bodies like acetone and beta-hydroxybutyrate) which smells… not great. This gets better over time and the more frequently you fast. You can brush your teeth more often, or you can choose xylitol gum.
- Pulse or resting heart rate increases – Sometimes this happens, sometimes it doesn’t. I found this gets better over time. The thought is that when you are in a deep fasted state your stress and cortisol levels are slightly elevated (fight or flight). Your body wants you to be active so that you can hunt for food. I have noticed my pulse at 5-10 bpm higher than normal.
- Sleep gets negatively affected on Day 2+ – This is a tough one, and can be more challenging than the fast itself. Again, I think this is related to elevated pulse and higher cortisol levels as stated above. Your body is in an elevated, higher-stress state to be ready to seek food. You may have trouble falling asleep, staying asleep, you may toss-and-turn more, and you may wake up very early. Some observations:
- When you get an hour or two less sleep than normal on a fast, it often doesn’t feel like you actually got that much less sleep.
- The quality of sleep ping pongs night to night. If you have a terrible 4 hour night of sleep, the next day you may have a nice 7-8 hour night to make up for it.
- Supplement protocol that I have found helpful about 45 minutes before bedtime is:
- 4 x 100 mg of phosphatidylserine/ps100 (reduces cortisol),
- 1 x X00mg of L-theanine (relaxes, calms)
- 3 x 100mg magtein/magnesium threonate (electrolytes, also helps with sleep).
- Avoid overcompensating for hunger with too much caffeine. It will add to your sleep issues.
- Lethargy, body heaviness – This seems to occur on Day 2+, especially right after waking. Salt helps, but the most effective way out of this rut is to push through and move (go for a walk, lift weights, etc). You can try to adjust the amount of exercise (both resistance training and walking) you are doing so that you don’t get so sore.
- Brain fog, low concentration, zoning out – This is pretty common, especially with beginners. You may find yourself. Try salt first. Move around. Then try MCTs. Maybe a nap. Try an activity that is less cognitively demanding.
- Possible GI issues
- During the fast, after a day or two, you may stop going #2. Alternatively, you may have looseness of your bowels. You can take a partial or full dose of loperamide (i.e. Imodium) to help things in that area.
- In preparation for breaking the fast, 30-45 minutes before for example, you can mix a glass of water with psyllium husk (i.e. Metamucil), and consume. The dietary fiber provides a good base to absorb your fast breaking meal. If you know you have somewhere important to be during/after your fast breaker meal, you can preemptively take loperamide (i.e. Imodium).
- Wanting to taste – You have been socialized to have three meals a day. It is not normal to completely turn off one of your five senses for an extended period of time. You may feel like you want to eat, just because you are bored, or you want to taste something. You could use this as an opportunity to practice mindfulness or stoicism and power through. Or you could try to add some variety to what you actually consume:
- Salt: Try all the different flavors of LMNT packets. One time I went to a fancy salt/spice shop and got a variety of different salts (smoked, volcanic, spicy, onion, etc) and had a salt tasting at home.
- Beverages: Try different flavors of sparkling water. Squeeze lime or lemon juice into your water. Add flavored salts to your tea or coffee (I like adding chocolate salt to coffee). Try different kinds of herbal teas.
- Broth: Treat yourself to different flavors/brands of bouillon broth to enjoy while others are having a meal.
- Feel cold – Your adjusted metabolism may not generate as much heat as normal. You may feel cold (I estimate 5 degrees cooler) or have cold hands. Wear more clothes or move around.
- Nausea – In my experience, this happens relatively infrequently, but it can happen. It usually will go away in 45 min to an hour. If it doesn’t, try more salt. If that still doesn’t help or you feel truly ill, then stop the fast.
- Wired, jittery – While fasting, your body may be more sensitive to caffeine. Additionally, you may be consuming more caffeine than usual either to suppress hunger or because you feel like consuming something other than water. The obvious solution here is to consume less caffeine. Switch to lower caffeine drinks (green tea, decaf, etc). Don’t drink caffeine after 2 PM. If you feel too “cracked out” you can try taking L-Theanine.
- Too much weight loss – First, let me say that most people will not have this problem. However, some people are naturally skinny or too skinny. Some people can become too obsessed with fasting, do it too often, and don’t make an effort to re-gain weight (and muscle in between fasts). If you are in this rare cohort, then DO NOT FAST. Or at least increase the time between your fasts.
- Strength loss – See exercise article.
- Muscle loss – See exercise article.