Is intermittent fasting for you?
Even though it is an ancient practice, only recently did intermittent fasting gained notoriety in the Western world. However, this diet still continues to cause controversy and to be the subject of many questions.
What first sparked interest in this subject was the fact that, in 2016, Yoshinori Ohsumi won the Nobel Prize in Medicine for his discovery on the mechanisms of autophagy in yeast cells. Autophagy is the process by which cells degrade and recycle their aging components.
This research is certainly a great starting point for studying the effects of fasting on human metabolism, but we cannot extrapolate the findings that occurred in yeast, or another animal, to humans.
What is intermittent fasting?
This is an eating strategy that alternates periods when we eat, known as eating windows, with periods where we simply stop eating.
There are several protocols that can be followed, that vary in the length of the eating window and the frequency during the week. The most common ones involve skipping breakfast or dinner, or having those meals at different times so that the fasting time is longer, such as having dinner at 7pm and breakfast at 9am (fasting for 14 hours), snacking at 5pm and breakfast at 9am (fasting for 16 hours), or even dinner at 9pm and lunch at 1pm (fasting for 16 hours). But there are also more radical approaches, where you can go 24 hours without eating, which translates into only one meal a day.
How can narrowing the eating window bring benefits?
Supporters of intermittent fasting believe this diet improves various metabolic parameters such as blood cholesterol levels, insulin resistance, which can develop into diabetes, and some markers of liver health, blood pressure, and even gut regulation. However, this evidence has only been significantly studied in animals, and these effects have been shown to be much less significant in humans, although it seems more likely that we may see these positive effects in obese individuals.
Thus, the improvement in metabolic markers will most likely be a consequence of weight loss, regardless of the strategy used.
What should you take into account?
First of all, it is essencial for you to consider consulting a nutrition professional that will help you tailor your meals to a shorter eating window. Whatever your goal may be, it is important to ensure that you are getting adequate nutritional intake and that all your meals are balanced.
In addition to this, this practice can have negative consequences in individuals with certain diseases or specific particularities, so individualized dietary counseling is of utmost importance. This is the case with diabetics, pregnant or breastfeeding women, children and adolescents, and people in a state of malnutrition or with some type of eating disorder, such as bulimia and anorexia, where this approach can be counterproductive.
Is intermittent fasting the best strategy to lose weight?
This approach is often associated with "just another fad diet" to lose weight. However, it can be a valid strategy for those who cannot stick to conventional diets, although it cannot be considered a better strategy for losing weight when compared to calorie deficit, i.e., restricting energy intake with the goal of spending more than we take in.
Therefore, this diet can be a strategy, like many others, for these cases. If we rarely wake up hungry and even force ourselves to eat because we have always heard that breakfast is the most important meal of the day, it may even make sense that our first meal of the day is lunch, and in this way we can easily reduce our daily energy intake.
In today's society, where we have a high prevalence of overweight and obesity and where we are offered miraculous solutions to combat them, fasting may have some benefits in relation to other diets that always imply a huge effort. And, most of the time, the results are not lasting, to the extent that by skipping one meal, we may have more leeway in the others. On the other hand, it can also be more difficult to adhere to because of the social context that we give to meals and the importance they have in our personal relationships. And that is why the nutrition professional is the ideal person to help you find the best strategy for your case.
- Patterson RE, Sears DD. Metabolic Effects of Intermittent Fasting. Annual re - view of nutrition. 2017
- Pellegrini, M., Cioffi, I., Evangelista, A. et al. Effects of time-restricted feeding on body weight and metabolism. A systematic review and meta-analysis. Rev Endocr Metab Disord. 2020
- Manoogian ENC, Chow LS, Taub PR, Laferrère B, Panda S. Time-restricted Eating for the Prevention and Management of Metabolic Diseases. Endocr Rev. 2022
- Liu K., Liu B., Heilbronn LK. Intermittent fasting: What questions should we be asking?. Physiology & Behavior. 2020