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  • Brindley Brooks

Intermittent Fasting for HS

Medically Reviewed by Jillian Ondreyka, MPH, RDN, IFNCP, IBCLC, CLT

Please read the entire article, to include the disclaimers, and check with your physician prior to beginning a fasting regiment.

Any time that you are not eating, you are intermittently fasting. Intermittent fasting is one of the oldest dietary interventions with powerful therapeutic potential.

Intermittent fasting should be considered a part of everyday life; for example, you most likely fast between dinner and breakfast the next day, a period of approximately 10-14 hours. During the periods of eating be sure to incorporate high protein and vegetable foods and drink plenty of water.

Some of the changes that occur in your body during fasting include:

Insulin levels: Blood levels of insulin drop significantly, which facilitates fat burning

Reduction in insulin resistance: Lowering Your Risk of Type 2 Diabetes

Increase in human growth hormone: The blood levels of growth hormone may increase as much as 5-fold. Higher levels of this hormone facilitate fat burning and muscle gain and have numerous other benefits.

Cellular repair: The body induces important cellular repair processes, such as removing waste material from cells.

Gene expression: There are beneficial changes in several genes and molecules related to longevity and protection against disease.

Intermittent fasting can also:

  • Reduce oxidative stress and inflammation in the body

  • Induce various cellular repair processes

  • Change the function of cells, genes and hormones

During the periods of eating be sure to incorporate high protein and vegetable foods and drink plenty of water.

Examples of Fasting Methods:

Shorter fasts (<24hrs)

Intermittent fasting offers plenty of flexibility; you can fast for as long or short as you like, but longer fasts than a few days may require medical supervision. Generally, shorter fasts are done more frequently.


This way of doing intermittent fasting involves daily fasting for 16 hours. Sometimes this is referred to as an 8-hour ‘eating window’. You eat all your meals within an 8-hour time period and fast for the remaining 16 hours. Generally, this is done daily or almost daily.

For example, you may eat all your meals within the time period of 11:00 am and 7:00 pm. Generally, this means skipping breakfast, but some people prefer to skip dinner instead. You typically eat two or three meals within this 8-hour period.


This involves a 4-hour ‘eating window’ and a 20-hour fast. For example, you might eat between 2:00 pm and 6:00 pm every day and fast for the other 20 hours. Generally, this would involve eating either one meal or two smaller meals within this period.

Longer fasts (>24 hours)

24-hour fasts

This way of doing intermittent fasting involves fasting from dinner to dinner (or lunch to lunch). If you eat dinner on day 1, you would skip the next day’s breakfast and lunch and eat dinner again on day 2. This means that you are still eating daily, but only once during that day. This is generally done two to three times per week.

5:2 fast

This is the version of intermittent fasting that has the most scientific support, as most studies on intermittent fasting. 5:2 involves five regular eating days and two fasting days. However, on these two fasting days, you are allowed to eat 500 calories each day. These calories can be consumed at any time during the day, either spread throughout the day or as a single meal.

Alternate-day fasting

Another related approach to 5:2 is to have “fasting” days with 500 calories, not just twice a week, but every other day.

36-hour fasts

This involves fasting for the entire day. For example, if you eat dinner on day 1, you would fast for all of day 2 and not eat again until breakfast on day 3. This is generally 36 hours of fasting. This may provide a more powerful weight loss benefit and the other great benefit is that it avoids the temptation to overeat dinner on day 2.

Extended fasting

Generally for fasts greater than 48 hours, a general multivitamin is recommended to avoid micronutrient deficiency. Fasts longer than a few days may require medical supervision.

Fasts more than 3 days are discouraged due to high risk of refeeding syndrome, a dangerous shift in fluids and minerals that can occur when food is reintroduced after a long fast, as well as possible vitamin and mineral deficiencies.

If you choose to fast longer than 72 hours, this is done at your own risk. Dry fasting is not recommended.

Important: Although drinking plenty of water during fasting is important, please be sure not to overdo it.

Water Intoxication

Also known as water poisoning, water intoxication is the disruption of brain function due to drinking too much water. Drinking a lot of water increases the amount of water in your blood which can dilute the electrolytes in your blood, especially sodium. When sodium levels fall below 135 mmol/L, it is called hyponatremia. Sodium helps balance fluids between the inside and outside of cells. When sodium levels drop due to excess water consumption, fluids shift from the outside to the inside of cells, causing them to swell. When this happens to brain cells, it can produce dangerous and potentially life-threatening effects. Water intoxication results from drinking too much water. The excess water dilutes blood sodium levels and causes fluids to move inside cells, which then swell.

Your kidneys can eliminate about 5.3-7.4 gallons (20-28 liters) of water a day, but they cannot rid themselves of more than 27-33 ounces (0.8-1.0 liters) per hour. Therefore, in order to avoid hyponatremia symptoms, you should not drink more than 27-33 ounces (0.8-1.0 liters) of water per hour, on average.

Disclaimer: While intermittent fasting has many proven benefits. Discuss with your physician before beginning along with potential dangers in regards to medications (especially for diabetes, where doses often need to be adapted). Discuss any changes in medication and relevant lifestyle changes with your doctor.

People who should NOT fast include:

  • Those who are underweight or have eating disorders like anorexia

  • Women who are pregnant or breastfeeding or who are considering becoming pregnant

  • People under the age of 18

Do NOT fast unless approved by your physician if you have the the following:

  • Diabetes mellitus – type 1 or type 2

  • Take certain prescription medication

  • Gout or high uric acid

  • Serious medical conditions, such as liver disease, kidney disease, or heart disease

Possible side effects with fasting:

  • Extreme Hunger

  • Constipation

  • Dizziness

  • Heartburn

  • Muscle cramps

  • Headaches

Resource Links:

Review other articles on diet and nutrition below:

Content in this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking treatment because of something you have read on this website.

Written by Denise Panter-Fixsen

Edited by Brindley Kons Brooks

Medically Reviewed by Jillian Ondreyka, MPH, RDN, IFNCP, IBCLC, CLT


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