Welcome to Keto Sister.  I wrote two posts previously about fasting that describe:

  • what is fasting.
  • how does fasting differ from starvation (when done properly).
  • the benefits of fasting.
  • types of fasting and meal timing.

If you have not read these posts yet, please read them before reading what is written below.

Today’s post explains the right and wrong ways to fast.  Yes, there are right and wrong ways to fast! Just as I cover the right and wrong ways to eat at a deficit (because you can overdo dieting), a person can also overdo fasting.  Fasting is a great means of reducing body fat and it works well when combined with a low carb eating strategy because it is easy to do.  Eating low carb generally eliminates hunger, and fasting requires you to go longer periods without eating which is easy to do when you are not hungry.  In fact, it can be so easy to do that people overdo it.

What are some of the right ways to fast?

  • Skip a meal (breakfast, lunch OR dinner) and eat extra during the other meals.
  • Skip a meal (breakfast, lunch OR dinner) and eat extra the next day.
  • Skip two meals and fast for 24 hours, and then stuff your face for the next 24 hours (eat over your macros).
  • Skip breakfast, then eat all your meals for the next two days, then skip lunch, then eat the next five meals, then skip dinner.

What are some of the wrong way to fast?

  • Skip breakfast, skip lunch, then eat a regular dinner.
  • Skip breakfast, have Bulletproof Coffee (BPC) for lunch and then eat regular dinner.
  • Drink BPC for breakfast, BPC lunch and BPC dinner.
  • Drink bone broth for days on end and then limit food to 500 calories when you finally do eat because dieting is the only way to lose weight.  (Sigh.)

Wait… doesn’t fasting only work because you reduce calories?  Isn’t it basically another way to diet?
No and no.  Fasting works because you eat during a compressed eating window.  If you eat your first meal of the day at 10 am and finish your last meal by 6 pm, then your eating window is 8 hours and you fast for 16 hours (or 16/8).  Because your body goes sixteen hours without eating, it draws its energy needs from your body fat stores.  Your burn fat during the sixteen hours that you do not eat because your energy needs are continuous through a day.  The longer you can go without eating, the greater opportunity you give your body to burn up its fat stores and also reduce glucose and insulin levels for those with excess fat, glucose and insulin in their bodies.  It is important, however, that you eat a full day’s calories when you do eat.

As I have explained in previous posts, the body goes into a state of nutritional ketosis because foods high in glucose are eliminated (or substantially reduced) in the diet.  If you further limit foods so that you are not eating enough protein or enough fat or are only eating one meal per day, then you are likely also reducing total calories for the day.  Your body is a smart engine that needs external fuel sources to keep it running.  If you do not eat enough food on top of not eating a lot of carbs, your body will recognize that it is not getting enough fuel and it will decide that you are starving.  Why else would you not eat enough carbs AND also limit total calories?

Fasting does not work require that you limit when you eat, nor does it require that you limit how much you eat.  In other words, despite what people assume about fasting, it does not work BECAUSE you cut calories. Fasting works because of the time you go without eating, but you do have to eat.  And when you eat, you do have to eat enough to counter balance the effects of fasting.  Trust me when I tell you this—if you cut carbs very low (eating under 75 grams a day is low) and also skip meals so you eat during a compressed eating window and then you diet or cut calories on top of it, your will eventually tell your thyroid that there is not enough food around and that you are in a famine.  And how will your body respond?  It will help you out by slowing your metabolism so you burn less body fat so you can live longer.  (This is a situation that you create which means it is a situation that you can avoid.)

I am a big fan of high and low calorie days for fat loss.  A person can choose to eat 1,000 calories one day, then eat 2,400 calories the next day (which averages to 1700 calories across two days).  The variation between high and low calorie days on its own increases the metabolism and your body never catches on to the low calorie days.  It’s eating low calorie for too many days in a row that is dangerous.  A person can also skip breakfast one day and eat until satisfied for the next few meals in a row.  As long as the body receives an abundance of calories when you do eat, fasting is a strategy that works very well for fat loss.

ONE MORE THING…A word for those who should not be fasting (you know who you are)

Women and lean people, or those within 10 pounds of goal weight, should not fast every day.  I have been doing an experiment on myself of eating twice a day, at least 2,000 calories most days and sometimes more, to see whether a lean woman can handle fasting on a daily basis.  It backfired!  I am now facing “adrenal fatigue” (which just means I overstressed myself) because I was fasting every day, even though I was eating enough calories.  Even if you eat enough, fasting every day may not be a good idea for those who are lean, for women of childbearing age, or for those who suffer any gut issues, thyroid issues, adrenal issues, have trouble sleeping, are losing your hair, have any hormonal or energy issues, or are pregnant/breastfeeding.  These folks may need to eat three meals a day and can experiment with fasting on alternate days or randomly as I suggest above.

Any questions about right and wrong ways to fast?  Comment below.  Thanks for reading.