The Effects of Intermittent Fasting on Metabolic Syndrome

by Amylee Amos PhD, RDN, IFMCPLifestyle
Section of watermelon set up as a clock face

In the United States, the incidence of metabolic syndrome is of epidemic proportions and continues to rise. As of 2015, approximately 35% of adults in the United States and 50% of adults over the age of 60 have metabolic syndrome (1).  This is alarming when considering the many comorbidities associated with metabolic syndrome, including Alzheimer’s disease, cancer, cardiovascular disease, kidney disease, and more. The humanitarian impact of these diseases, and the financial burden they place on our healthcare system warrant the investigation of new therapies for primary prevention. 

A clinical diagnosis of metabolic syndrome is made based on the presence of three or more of the following factors: elevated fasting glucose, elevated triglycerides, low levels of  high-density lipoprotein cholesterol (HDL), hypertension, and central obesity (1). Specific criteria apply to each of these factors and in some cases vary based on ethnic group. Diet and lifestyle play a major role in the development of metabolic syndrome. Metabolic dysregulation as a result of poor diet and lifestyle choices including insulin resistance, inflammation, and oxidative stress all contribute to the pathophysiology of metabolic syndrome.

Intermittent fasting (IF) appears to be a promising intervention with regard to preventing and reversing metabolic syndrome. IF generally refers to eating patterns in which individuals undergo extended periods of time with reduced or no calorie intake, followed by times of normal calorie intake, on a recurring and structured basis. In recent years, IF has been studied for its effectiveness in improving health outcomes and promoting healthspan and longevity (2). Intermittent fasting is of particular interest because unlike many nutrition and lifestyle interventions to promote health, implementing it is completely free, takes no additional time out of your day, and is incredibly simple to start. 

Classification of Intermittent Fasting

While IF has become a popular term in the media and part of a growing nutrition and lifestyle trend in recent years, the concept of IF is not new. Various cultures throughout the world have used IF for centuries as a part of religious traditions and medicinal interventions. More recently, clinical research has explored how IF can be used to directly modify pathophysiology and explore the mechanisms of how this can occur. Many different types of IF exist and have been utilized in research and in general, researchers disagree on how these types of fasting should be classified. However, some of the main groups of IF include alternate day energy restricted fasting, which includes calorie restriction of approximately 70% every other day; two day IF, in which individuals consume only 500-700 calories on two days per week; time restricted eating, which entails limiting the eating window to 6-10 hours per day; and fasting mimicking diets, which consist of a very low calorie structured diet for five consecutive days out of each month for a predetermined number of months (3). 

Benefits of Intermittent Fasting

Each of the different types of IF have varying benefits and limitations. Additionally, the specific benefits attributed to intermittent fasting vary between studies. However, some of the effects of IF on various organ systems include weight and fat mass loss, increased parasympathetic tone, enhanced neuroplasticity, increased heart rate variability, increased insulin sensitivity, and reduced inflammation biomarkers, glucose metabolism biomarkers, and biomarkers of oxidative stress (2). The wealth of scientific literature largely agrees that a top benefit of IF can be attributed to weight loss achieved as a result of IF. What’s especially interesting is that in studies, subjects are able to maintain that weight loss as long as they maintain their IF regimen. 

The form of IF with some of the best rates of compliance and acceptability among patients is time restricted eating. In addition to the benefits mentioned above, individuals who followed time restricted eating experienced other non-anthropometric and non-biochemical benefits including improved sleep, increased energy levels, and decreased hunger at bedtime (3). Whether these benefits were the result of the time restricting eating itself or the weight loss remains unclear. Regardless, the high compliance ability of time restricted eating, specifically because it does not require an intentional decrease in energy intake, makes it a promising target for future research.

If you currently follow the Ketoflex Nutrition Plan, you are already practicing time restricting eating and experiencing these benefits. However, there may be additional forms of IF that could be of benefit, including periodic use of the fasting mimicking diet. Whenever you change your eating patterns, and especially when considering any forms of fasting, it is imperative to meet with a registered dietitian who can help ensure that you implement IF safely and without any risk of harm. At the Amos Institute, our registered dietitians are experts in the various forms of fasting and can help you identify which forms will most benefit you based on your unique needs. To join our program today, sign up here


  1. Rakel, D. (2018). Insulin resistance and the metabolic syndrome. Integrative medicine (4th ed.) (pp. 320-333) Elsevier.
  2. Mattson, M. P., Longo, V. D., & Harvie, M. (2017). Impact of intermittent fasting on health and disease processes. Ageing research reviews, 39, 46–58.
  3. Rynders, C.A., Thomas, E.A., Zaman, A., Pan, Z., Catenacci, V.A., & Melanson, E.L. (2019). Effectiveness of intermittent fasting and time restricted feeding compared to continuous energy restriction for weight loss. Nutrients, 11, 1-23.