Functional Medicine

By Nicole Bladin, NP-C, FNP, MSN, AFMCP

September 9, 2023

Is Intermittent Fasting right for you?

Intermittent fasting is a broad term used to describe cycles that alternate between periods of restricting calories and periods of not restricting calories. Many people are using this as a weight loss tool which has been reported as being successful for a lot of people! This is great because this approach is accessible to anyone because it is free!

But, is intermittent fasting for everyone? Let’s dive in!….

Different types of intermittent fasting:

When fasting, individuals may either limit, or completely avoid calorie containing foods and beverages. Some common variations to intermittent fasting are¹:

Time restricted feeding (TRF): a shortened window of time when a person consumes calories. Typically someone will have a 12-16 hour window of fasting alternating with eating.

Alternate day fasting (ADF): a person will fast on one day and eat the next day. Typically, a person following this variation will restrict calories to no more than 600 on their fasting day. This can also be done to fit a person’s schedule for example fasting on every third day instead of every other day.

Modified fasting: a type of fast in which a person reduces calories by 10-20%, or reduces calories to 600 per day for a specified number of days per week.

Fasting mimicking diet (FMD): a ketogenic diet that is typically followed for five days once a month. This is a 5-day, very low-calorie, low carbohydrate, structured food plan.

Juice fasting: consuming only juice or broths for 10 days a month. This type of fasting and its health claims are not supported by scientific evidence.

Who benefits from intermittent fasting?

Shorter-duration human and animal studies show that fasting may be beneficial for insulin resistance, blood sugar, blood pressure, inflammation, short-term weight loss, and brain health^2,4.

This does not mean that intermittent fasting is right for all, however. Some studies do show increases in depression and difficulty sustaining daily activities, possible loss of free fat mass I.e. muscle mass, undernutrition and decrease in athletic performance, as well as alteration in sleep¹.

Who should not fast or fast with caution?

Fasting is not meant for those who are¹:
Frail
Pregnant or nursing
Children or adolescents who are still growing
Those with low blood pressure
Underweight
Those with eating disorders
Those with HPA axis dysfunction or “Adrenal Fatigue”

It is important to dive into fasting with the advice of a medical professional who can guide you on the type of fasting that will A – fit your lifestyle and be do-able, B – guide you on how to fast especially if you have any chronic disease, and C – provide you with some nutrition tips for your eating window to avoid malnutrition which could be a major driver of negative side effects of intermittent fasting.

General recommendations for intermittent fasting:

Drink plenty of water. You may also enjoy some herbal teas and don’t forget about electrolytes!
Don’t overdo the exercise. Stick to non-intense exercise like yoga, walking, tai chi.
Break your fast with non-processed, whole foods that are nutrient-dense.
Watch your movement, you may be dizzy initially!
Stop fasting if you don’t feel well and call your practitioner.

Further research is needed to determine whether fasting is effective for improving health in the general population, higher-risk people, and those with chronic disease. Additional knowledge is also needed regarding the mechanisms of benefit and the optimal frequency and duration of fasting in apparently healthy and high-risk individuals³. Fasting is a promising, FREE tool to improve health outcomes!