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Although the title of this post is who should fast I want to start out with who should not fast. If you are in one of those categories then it does not matter if you fit the other criteria, you should not be fasting at this point.
Who should not fast
Pregnant and breastfeeding women should not be fasting. You have a baby to care for, unborn or newly born. Either way you need your calories to feed and care for your baby. Of course it goes without saying that those should be nutrient dense calories of real food, so that both mother and baby will be nourished.
Children under age 18 are still growing and should not fast. They don’t have to be pushed to eat all the time when they are not hungry, but they should not be fasting as a practice. Again healthy food is in order to feed the growing body.
Those who are malnourished or underweight should not be fasting. This also includes those with eating disorders like anorexia and bulemia, as it can encourage those kinds of eating issues. If you are not sure if you fall into that category, ask a friend or family member if you are underweight or malnourished. Sometimes it is hard for us to be objective about our own bodies.
Who should fast
That leaves the rest of us, which is a good part of modern America and the western world.
Those who want to lose weight may find their weight loss goals finally stop eluding them. Weight gain and loss is not a calories in, calories model as we have been taught for years. It is primarily a hormonal issue with the hormone insulin being one of the primary factors in weight gain or loss. Fasting means periods of not eating and skipping at least 1 meal in a given day. Not eating lowers insulin levels and encourages the body to burn its fast reserves.
Those with signs of insulin resistance would do well to fast. Insulin resistance is when your cells are no longer sensitive to insulin and the body produces more insulin to force the cells to use the glucose in the bloodstream. This starts with high levels of insulin which then leads to higher levels of insulin and the cycle continues to grow. If you don’t eat your blood sugar levels will come down and if your blood sugar levels come down then your insulin levels will also decrease.
This category and that of those who need to lose weight will most likely overlap. There are some who are insulin resistant and do not have any significant weight to lose. The only way to really check that if you are not overweight at all is to get some lab work done and see what your glucose and insulin levels are.
I found out that I was experiencing insulin resistance when I had a HgbA1c test done and found that my level was 5.7, which is at the bottom of the levels that is considered pre-diabetes. I started checking my blood sugar levels at different times in the day. Weight loss and fasting has brought those numbers down at least 10-15 points and I am no longer considered pre-diabetic.
Who should be cautious
There are several different categories of people who should be cautious about fasting and should check and work with their doctor or a medical coach so as to avoid problems. This includes those with gout, those taking medications, those with diabetes (type 1 or 2) especially if taking medications for that, and those with Gerd (gastroesophageal reflux disease). Anyone in these categories should consult with their doctor and should fast with close supervision.
Those with gout need to take care because fasting can raise the levels of uric acid which can worsen gout. Most people with gout can fast but be aware of the risk.
Those with diabetes run the risk of low blood sugar, especially if taking insulin or oral medications. Signs of low blood sugar include shaking, sweating, nausea, feeling faint, and nervousness. This can cause more severe symptoms and lead to confusion, seizures and passing out. For a diabetic to fast there needs to be communication with your doctor and a close monitoring of blood sugars throughout the fasting time.
Those taking other medications need to be aware of meds which need to be taken with food. Sometimes the fasting schedule and medication schedule can be adjusted to accomodate each other.
Finally those with GERD need to be aware that fasting can worsen symptoms of GERD because there is nothing in the stomach to absorb acid. After weight loss GERD will often resolve so fasting is useful for long term treatment. If fasting causes symptoms of heartburn and acid reflux eating salad greens throughout the day can help to prevent problems and still allow for the benefits of fasting.
This material was taken from Dr. Jason Fung’s excellent book The Complete Guide to Fasting. This is my Amazon affiliate link if you want to read more.
For more on fasting you can read my review of his book or my experience with intermittent fasting.
Join me for the next 10 Day Intermittent Fasting Challenge.
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How about a underactive Thyroid. Treated with levothyroxine daily?
Many women with hypothyroid are finding their thyroids improve with fasting. There is a relationship between the thyroid and insulin resistance, so fasting will happen many people in this case. I recommend moving in slowly and not fasting longer than 14 hours to start and then as you increase hours keep some of your days on the shorter fasts of 12 to 14 hours and some you can work into 16 and up.