A recent opinion published in Clinical Nutrition ESPEN provides a highly detailed review of intermittent fasting and the ketogenic food regimen, in addition to strategies to use a mixture of those approaches to administer chronic health conditions.

Study: Intermittent fasting with Ketogenic Diet: A mixture approach for management of chronic diseases. Image Credit: EZ-Stock Studio/Shutterstock

What’s intermittent fasting?

Intermittent fasting is a time- or food-restricted feeding pattern, wherein foods and drinks are allowed inside an outlined period followed by fasting.  

In time-restricted fasting, a person can eat meals and snacks one to thrice every day, depending on the time-restricted eating pattern. The fasting period can vary between 12 and 23 hours a day. In periodic fasting, the duration of fasting can range from two to 21 days or longer.

Time-restricted fasting is used to step by step reduce calorie intake over time. This approach considers small eating windows within the morning and early afternoon to be higher than late afternoon or evening eating windows by way of reducing fat accumulation, insulin resistance, and inflammation.

Previous studies have shown that time-restricted fasting helps manage body weight and improve muscle mass. Furthermore, prolonged time-restricted fasting has been shown to enhance metabolism and protect against cardiovascular and metabolic diseases.

In diet-restricted fasting, the main focus is given to the sort and amount of food that may be consumed through the fasting period. There are a lot of sorts of diet-restricted fasting, including water-only, drinks-only, and calorie-restricted fasting. In pure fasting, nonetheless, foods and drinks are completely prohibited.

Diet-restricted fasting may be used along with any style of food regimen plan, including vegan, vegetarian, paleo, ketogenic, or gluten-free diets. In truth, even water-only fasting has been shown to be protected and effective in managing certain diseases.

Each time- and diet-restricted fasting are equally effective in managing body weight. A mixture of each approaches can be effective in managing chronic diseases.

What are the stages of intermittent fasting?

Intermittent fasting may be divided into 4 stages, including fed, post-absorptive to early fasting, fasting, and long-term fasting stages.

Within the fed stage, which starts immediately after feeding, glucose acts because the fain fuel, whereas insulin acts because the regulatory hormone to metabolize glucose and inhibit lipolysis. Excess glucose is stored within the adipose tissue.

Within the post-absorptive to early fasting stage, insulin levels decline, which subsequently results in the initiation of glycogenolysis to offer glucose. Lipolysis can be initiated on this stage.

Within the fasting stage, glucose still acts because the fundamental energy fuel; nonetheless, a shift of fuel source from glucose to fatty acid is initiated. This sometimes causes flu-like symptoms, commonly often called ‘ketoflu’.

In the course of the long-term fasting stage, an entire metabolic switch occurs, where fatty acids turn into the fundamental energy fuel. Furthermore, branched-chain amino acid catabolism is inhibited on this stage, thus resulting in protein-sparing and reduced insulin levels.  

In intermittent fasting, the fasting duration mustn’t initially exceed 12 hours; nonetheless, the duration may be step by step increased to attain an entire metabolic switch to fatty acids. This known as the upkeep phase, which may be continued for prolonged periods of time, starting from weeks to months.

What’s the ketogenic food regimen?

The classic ketogenic food regimen refers to a calorie-rich food regimen wherein fats, carbohydrates, and proteins constitute 70%, 10%, and 20% of every day calorie intake, respectively. Dietary fats include natural, in addition to unprocessed monounsaturated and polyunsaturated fats, from different food sources. Saturated fats from animal-based foods can be used, as they may be rapidly metabolized to extend high-density lipoprotein (HDL) levels of cholesterol within the blood.

Modified ketogenic diets, comparable to the modified Atkins food regimen (MAD) and low glycemic index food regimen, were developed within the 2000s to scale back fat consumption and increase carbohydrate consumption.

In healthy individuals, a mixture approach of intermittent fasting and the ketogenic food regimen may be applied without specific monitoring. Nonetheless, in patients with chronic diseases, tolerability, and possible complications must be monitored. More specifically, continuous monitoring of body weight and blood levels of glucose, ketones, hemoglobin, lipid parameters, and inflammatory markers is crucial.

Combining intermittent fasting with ketogenic food regimen

Each intermittent fasting and the ketogenic food regimen induce a metabolic switch from glucose to fatty acids. Sirtuins, that are NAD+-dependent lysine-specific deacetylases, play vital roles in regulating glucose and fat metabolism. Intermittent fasting has been shown to induce Sirtuin expression. 

A mixture of intermittent fasting and the ketogenic food regimen may be applied to administer various chronic diseases. Each strategies are effective in protecting against cerebral ischemia and hypoxia, in addition to controlling intracranial pressure in conditions of traumatic brain injury, ischemic stroke, and standing epilepticus.

Any such combination therapy may very well be useful in managing various diseases through metabolic remodeling, including diabetes, cardiovascular diseases, and autoimmune diseases. A successful application of this mixture approach relies on various aspects, including patient-related and food regimen aspects.

Necessary considerations

Before implementing the mixture of intermittent fasting and the ketogenic food regimen, patients’ medical and family history of disorders, in addition to a social history of alcoholism and drug abuse, must be rigorously analyzed.  

An expert discussion with patients in regards to the health advantages of intermittent fasting and the ketogenic food regimen is significant for his or her motivation. Apps that track the duration of fasting, weight changes, and health parameters are also effective in motivating patients.    

Patients must be supplied with adequate time to adapt to the changes of their dietary habits. Upon the achievement of desired outcomes, patients must be rewarded to support their continued motivation.

Regarding food regimen aspects, accurate calculation of calorie requirements and the next formulation of an appropriate food regimen plan is essential before implementing the mixture therapy. An appropriate ratio of macronutrients including carbohydrates, proteins, and fats must be maintained within the food regimen.

The monotony of food regimen may be avoided by selecting foods from different sources and recipes. Low glycemic index foods and vegetables are really helpful.

Adequate hydration can be highly essential. Patients considering water-only fasting should eat between two and three liters of water day-after-day.

The mixture therapy might not be appropriate for kids, pregnant women, and breastfeeding women. As well as, patients with lively infection, eating disorders, diabetic ketoacidosis, and acute or chronic pancreatic or liver disorders should avoid practicing a mixture of intermittent fasting and the ketogenic food regimen.

Journal reference:

• Arora, N., Pulimamidi, S., Yadav, H., et al. (2023). Intermittent fasting with Ketogenic Diet: A mixture approach for management of chronic diseases. Clinical Nutrition ESPEN. doi:10.1016/j.clnesp.2023.01.024.