This blog post is a bit more `sciencey’ than our usual blogging style as it’s written with Nutritional Therapist’s and other Health Professionals’ in mind. Here we look at why Intermittent Fasting works, the various regime definitions and how best to support your clients on their fasting journey. A fully referenced version can be requested via the `contact us’ page.
Why Intermittent Fasting works
When food is available, the human body has evolved to burn glucose for fuel and to grow. When it is scarce, it has evolved to use stored fat for fuel and to repair. Increasingly, modern life is associated with a disproportionate time spent in growth mode due to high eating frequencies, high calorie intake, sedentary lifestyles, chronic stress and longer life spans. This dysregulation is associated with increased incidences of obesity, metabolic disease and diminishing health spans.
Intermittent fasting helps redress this balance. The benefits most associated with intermittent fasting are weight loss, metabolic flexibility and as a strategy to age well. It can also be a useful client protocol for other states such as those associated with brain or gut health and auto immune conditions.
Types of Intermittent Fasting
The term intermittent fasting is an umbrella term covering a range of regimes that oscillate between periods of eating and not eating, without malnutrition. In general, these fasts are classified as either periodic fasts or time restricted eating.
Periodic fasts cover regimes where no calories or a restricted calorie allowance are consumed for a period of time and includes water fasts, alternate day fasts and fasts that include some calories such as the popular 5:2 regime and the alternate day modified fast.
The benefits of this group of fasts are mediated by switching primarily to fatty acids and ketones for fuel and inactivating nutrient sensing pathway mTOR (mechanistic target of rapamycin) to stimulate cellular repair, autophagy and pro-ageing epigenetic factors. Fat and fatty acids support these transitions while glucose and amino acids inhibit them.
Therefore, for plans with a calorie allowance, it is increasingly being recognised that macronutrient composition plays a role in achieving the calorie restriction benefits. For clients focused primarily on weight loss, consider lower carb options for those meals and for clients focused on the cellular repair benefits, exclude the amino acids methionine and cysteine as these are particularly potent activators of the associated pathways. For all periodic fasting plans with a calorie allowance, recommend calories are consumed in one sitting, except for a small amount of fat if needed for compliance.
Time restricted eating regimes are plans where all food is consumed within a set time frame each day, typically less than 12 hours. A popular version is 16:8 where all food is consumed within 8 hours. Benefits are mediated by the same pathways as periodic fasts and additionally by syncing the individual’s circadian rhythm with their daily cycle of feeding and fasting. A dysregulation of this cycle is associated with excess calorie intake and accelerated ageing. Regular periods of this type of intermittent fast regulate these transitions and rhythms. It is important to note that any calories consumed during the fasting window start the biological clock. If those calories are from fat, the benefits associated with periodic fasts continue.
The right regime depends on individual client goals and lifestyle fit. Whatever the format, compliance can be difficult, especially over the long term.
Some clients will find adhering to an Intermittent Fasting harder than others. For example, clients with a degree of insulin resistance may require more support to adhere to their fasting plan. Insulin resistance delays the onset of the metabolic switch over to fatty acids causing a metabolic imbalance. Glucose and glycogen stores run low while insulin levels are relatively high so fatty acids cannot be accessed. This results in symptoms typically of hunger, moodiness and tiredness and reports of lapsing can be common during this time.
A recent study demonstrated that beliefs may also play a role in adherence to an intermittent fasting plan. Lapsed intermittent fasters were more likely to believe that a healthy meal plan included three meals a day and regular snacks. Whereas current intermittent fasters were comparatively unconcerned about skipping meals and were less likely to believe that breakfast was the most important meal of the day.
Before a client starts an intermittent fasting programme for those with insulin resistance, consider reducing daily eating frequency to 3 meals only within a 12-hour period for several weeks. For those with beliefs that intermittent fasting protocols are unhealthy, consider providing research and support to negate long held assumptions.
Intermittent fasting is a mild stressor. Assess a client’s overall stress tolerance and load to ensure that they do not become chronically stressed as this will negate the favourable hormetic response from fasting. In addition to lifestyle and nutritional stressors, it is important to understand that if the client is undertaking any additional intermittent challenges (such as high intensity exercise, saunas or cold showers etc.), as these are also mild stressors and have an additive effect. An intermittent fasting regime that is too advanced can also be a stressor. As the client becomes more proficient at fasting, adding other intermittent challenges and more advanced fasting protocols can be useful progressions.
Prepare clients with relevant tactics for use during their intermittent fast:
- Educate on how to differentiate between typical symptoms (hunger that passes, mild tiredness, moodiness, mild headaches) and those that indicate fasting is too stressful and the fast should be broken (significant day time tiredness, dizziness, feeling overwhelmed).
- Advise on useful strategies for those days where they are struggling. For example, sodium may be useful for some clients who have a history of electrolyte imbalance, black coffee and green tea can help with hunger pangs, MCT or coconut oil can support those struggling with hunger on periodic fasting regimes, apple cider vinegar can support insulin sensitivity and calorie restriction mimetic compounds can support the main fasting pathways overall.
- Calorie restriction mimetic compounds? These are components of some foods, often as polyphenols. The most commonly known include resveratrol, curcumin and quercetin. Current research indicates that this group of compounds mediate metabolic flexibility and support the transition of mTOR into repair mode where autophagy and longevity genes are activated. A synergistic blend of these compounds is useful as specific modes of actions and target sites vary. Here at Nutritionist’s Blend we use calorie restriction mimetics in our FASTING+ fasting sticks.
Ensure clients understand how to eat during their eating window:
- As intermittent fasters tend to have less eating opportunities, nutrient density is a useful area of focus. For those primarily focused on weight loss, lower carb or keto protocols may be appropriate. In addition, a calorie deficit may or may not be required depending on the selected programme.
Due to genetic and environmental variation, an individual’s response to fasting can vary both in general and on a daily basis. Intermittent fasting success is a constant balance between progress and ensuring it is a regular and repeatable practice for clients. If done correctly, compliance and progress can be long-term supporting a more optimal balance of cellular growth mode and cellular repair mode. This could help normalise weight, support more consistent energy levels and support healthier ageing. Regular client check-ins and programme reviews are therefore recommended, particularly during the first few months.
We hope your clients achieve their fasting goals
Nutritionist’s Blend team x