Intermittent fasting benefits and controversy
The concept of periodic fasting (intermittent fasting, abbreviation IF) is gaining more and more popularity among people interested in getting a fitness figure. Quite often, the main argument used to support the effectiveness of this type of method is the poor benefits associated with the consumption of meals every 2-3 hours. Nevertheless, quite recently there have been quite a few interesting studies describing the direct impact of short-lived fasting and IF methods on indicators related to body shaping and improving health.
Modified post every other day (modified alternate-day fasting, abbreviation ADMF) is definitely the most frequently used method in scientific research in overweight and obese patients. In the case of ADMF, “fasting days in which energy consumption is limited to 25% of energy demand (usually one meal – constituting approximately 25% of energy demand, consumed between 1200-1400) are alternating with days of unlimited consumption.
Before intense studies on the ADMF method began, several short-term studies on small groups of volunteers attempted to determine the effectiveness of other IF methods, in particular post-every second day (alternate-day fasting, abbreviation for ADF). The results of these preliminary studies were not conclusive. For example, Halberg et al., 2005, in a study of 8 overweight men, observed an improvement in insulin sensitivity and an increase in adiponectin levels after 2 weeks of using the IF method of extending the night fast to 20 hours 1. The adiponectin is a protein produced by adipose tissue. Its level is lowered in the state of insulin resistance and type 2 diabetes. In turn, Soeters et al., 2009 in another study involving 8 lean men did not confirm the beneficial effect of the same IF method on insulin sensitivity, and additionally in the studied men during the use of IF methods reported slightly greater reduction in resting metabolic rate (RMR) than in the standard diet 2. Frequently, the opponents of the IF methods refer to these tests, ignoring their limitations completely (duration: 2-3 weeks, sample size is only 8-16 people).
Fortunately, in the recent years, several more valuable studies (duration 8-12 weeks) have been carried out to clarify what benefits can be obtained by using short-term fasting, especially the ADMF 3. In these experiments, a number of positive effects were noted in the subjects
-Leduction of weight (-6-8% of the initial weight)
– Reduction of waist circumference
-Leduction of LDL cholesterol (-10-25%)
– Reduction in triglyceride levels (-30-40%)
– Increasing the size of LDL particles
In one of the studies, these changes in the lipid profile were correlated with favorable changes in the concentration of the mentioned adiponectin. It is also interesting that based on the research conducted so far, IF methods are less conducive to the loss of lean muscle mass than methods based on daily calorie restriction. For example, Klempel et al., 2013 in a study involving 32 women (aged 25-65 years, BMI in the 30-39,9 kg / m2 range) did not report a loss of lean body mass after 8 weeks of ADMF, regardless of the version used studied women – high fat (ADF-HF, 45% energy supplied from fat) or low fat (ADF-LF, 25% energy supplied from fat) 6. At the same time, the loss in body weight was 4.8% and 4.2 % of the initial mass. In addition, in a number of attempts that Dr. Krista Varady has been observed that after about 2 weeks of adherence to ADMF, the subjects are adapted to the diet regimen and the feeling of starvation is not intensified during fasting days 7. At the same time, on the days of unlimited consumption, the test subjects provide only about 100-110% of their energy requirements, which that they are on a diet with a substantial energy deficit.
You can read also: What is healthy lifestyle?Posted on: March 28, 2019