Like everything that becomes 'trendy', intermittent fasting has loyal followers and staunch detractors. However, beyond the experiences of some and the arguments of others, science is there to support with evidence the benefits of this practice or, as in this case, debunk negative myths.
According to a study conducted by experts from the University of Illinois (Chicago), led by Krista Varady, professor of kinesiology and nutrition, and published on June 24 of this year, four of the possible negative effects of intermittent fasting have no scientific basis to support them.
"For over two decades, I have been studying intermittent fasting and, throughout that time, I have been constantly asked if this type of meal planning is safe. The problem is that there is a lot of misinformation out there and many of the ideas circulating are not based on science, but on personal opinions," Varady stated.
Before delving into the subject, this team of researchers has distinguished between two main types of intermittent fasting. On one hand, there is alternate-day fasting, which, as the name suggests, involves alternating days of eating a very small amount of calories and other days of eating whatever one wants.
And, on the other hand, time-restricted feeding: one eats what they want (in moderation!) during a period that can range from four to ten hours (depending on the fasting method) and, during the rest of the hours of the day, no food is consumed (bone or vegetable broths can be consumed, and it is essential to drink plenty of water to avoid dehydration).
Well, initially, the researchers from the University of Illinois have concluded that both options are safe despite popular myths.
But there's more. Varady and her colleagues assert that intermittent fasting does not cause eating disorders. None of the studies conducted on this matter show that fasting has been the cause of participants developing such a disorder.
However, it must also be said that all studies excluded participants with a history of eating disorders. Furthermore, the authors of this research emphasize that people with a history of eating disorders should not try intermittent fasting.
Similarly, they urge pediatricians to be cautious in monitoring obese adolescents if they start fasting, as this group has a high risk of developing eating disorders.
Furthermore, intermittent fasting does not lead to poor nutrition. The researchers point to studies showing that the intake of sugar, saturated fats, cholesterol, fiber, sodium, and caffeine does not change during fasting compared to before the experience. The percentage of energy consumed in carbohydrates, proteins, and fats also remains unchanged.
Contrary to what is said, intermittent fasting does not cause excessive loss of lean muscle mass, a matter that was already debunked in a comprehensive article by ZEN worth revisiting. In this regard, they emphasize that people lose the same amount of lean muscle mass in weight loss processes, regardless of whether it is done through intermittent fasting or a different diet. In both cases, they stress the importance of increasing protein intake and engaging in strength training.
Finally, the specialists from the University of Illinois affirm that intermittent fasting does not affect sex hormones. In other words, despite concerns about fertility and libido, neither estrogen, testosterone, nor other sex-related hormones are altered by this practice.