We need to talk about Intermittent Fasting!
Despite the boom in the last months, due to the media encouragement, intermittent fasting isn’t a new practice. Since a few years it exists with some variations for the purpose of weight loss.
Intermittent fasting is the term used to appoint a food standard in which periods of fasting are alternated with feeding periods. There is a fasting period between 14 and 24 hours, followed by a food window, where you can eat as many meals as you deem necessary. In periods of fasting, in some schemes, it is allow to drink water and other non-caloric beverages.
Metabolically, it means put the body under stress, causing a release of counterregulatory hormones in order to keep blood glucose at adequate levels. At this moment, there is a fat mobilization for energy requirements and there is also mobilization of muscle mass.
Recently, a study from the University of Southern California brought the method back to the forefront but at this time as a potential cure for Diabetes.
Published at Cell Journal, in February, Cheng et al evaluated rats fed for four days with a hypocaloric, hypoprotein, hypoglycemic and hyperlipidic diet, receiving half of normal daily caloric intake, followed by three days with 10% of normal caloric intake, with 10 days of refeeding between the three tests. When analyzing the pancreas by rats, they found in those with Type 1 and type 2 Diabetes restoration of insulin production, reducing insulin resistance and an possible beta cell regeneration through insulin secretion.
It is noteworthy that the study showed promising results, but other studies are still needed to validate these findings in humans.
In 2016, the study of Carter et al, shown that in Type 2 Diabetes, two days of fasting followed by five days of usual meals is the same as continuous caloric restriction on improving glycemic control and weight loss.
Specifically for weight loss, literature is scarce and evidence is low, especially because of the most of studies are made in animals.
In a systematic review of 2015, when intermittent fasting was evaluated in the treatment of overweight and obesity in adults, no difference was found between intermittent fasting and usual dietary treatment in the medium term.
Similar results was found in the study of Harvie and Howell, in which no safety evidence was found in the long-term practice of intermittent fasting in weight loss on overweight and obesity treatment.
In the other hand, in 2016, Mattson et al showed that in rats submitted to intermittent fasting, an improvement in insulin and leptin sensitivity was found, also a reduction of body fat, reduction of the blood pressure levels, reduction of inflammation, increase of cerebral and cardiac resistence to stress and improvement in resistance to Diabetes. It was also found a delay in the progression of neurological dysfunctions and degeneration, such as Alzheimer's and Parkinson's.
Antoni, in 2017, also showed the benefits of intermittent fasting in glucose and lipid homeostasis in short and medium term, but still remain necessary long-term type studies.
• Does it seem like intermittent fasting has metabolic benefits? Yes
• Is there safety in this practice? Not yet, because long term effects are not known and studies must be validate in humans.
• Can intermittent fasting be used for weight loss? Better not, as is reported that weight regain happens after the period of fasting and the return to usual food pattern. The potential metabolic benefits are maintained, but weight is not.
• What to do with all this information? Keep an eye on what Science is producing and look forward to reliable and consistent results.
Cheng CW, Villani V, Buono R, Wei M, Kumar S, Yilmaz OH, et al. Fasting-Mimicking Diet Promotes Ngn3-Driven β-Cell Regeneration to Reverse Diabetes. Cell, 2017.
Jane L, Atkinson G, Jaime V, Hamilton S, Waller G, Harruson S. Intermittent fasting interventions for the treatment of overweight and obesity in adults aged 18 years and over: a systematic review protocol. JBI Database System Rev Implement Rep. 2015 ;13(10):60-8.
Antoni R, Johnston KL, Collins AL, Robertson MD. Effects of intermittent fasting on glucose and lipid metabolism. Proc Nutr Soc. 2017;16:1-8.
Mattson, M.P., et al., Impact of intermittent fasting on health and disease processes. Ageing Res. Rev. 2016.
Harvie M, Howell A. Potential Beneﬁts and Harms of Intermittent Energy Restriction and Intermittent Fasting Amongst Obese, Overweight and Normal Weight Subjects—A Narrative Review of Human and Animal Evidence. Behav. Sci. 2017.
Horne BD, Muhlestein JB, Anderson JL. Health effects of intermittent fasting: hormesis or harm? A systematic review.Am J Clin Nutr. 2015; 102:464–70.
Carter S, Clifton PM, Keogh JB. The effects of intermittent compared to continuous energy restriction on glyaemic control in type 2 Diabetes; a pragmatic pilot trial. Diab Research and Clin Pract. 2016.