Intermittent fasting = Losing Weight easily?

It should be noted that the obesity epidemic is having a greater impact today and continues to increase. Therefore, interest in the search of dietary strategies to manipulate body composition has increased. One of the most commonly prescribed dietary treatments is dietary restriction of about 500-700 kilocalories along with a loss of 5-10% of body weight per year. But its adherence is usually in jeopardy between the first and fourth month, as it is very aggressive. As a result, interest has increased in the search for alternative strategies, and this is where intermittent fasting comes in. Intermittent fasting turns out to be a strategy that can be more easily maintained in the long term.

Intermittent fasting consists of restricting solid food intake for a prolonged period of time, establishing regular fasting and feeding cycles. This strategy is presented with high clinical interest due to its beneficial effect on weight, body composition and metabolism. These are observed without reducing daily caloric intake and it has also gained popularity in our society as a method for prevention and promotion of health.

Physical exercise is essential for our health

Along with an appropriate dietary strategy regular exercise should be practiced as it is associated with a lower risk of morbidity and mortality, promoting mental health and the late onset of dementia.

However, it should be noted that such dietary strategies can have certain consequences if not used properly and with supervision by a nutritionist. One unfavorable consequence can be the loss of lean body mass. An important component of lean body mass is skeletal muscle and its maintenance will depend on the net protein balance and energy balance. During energy restriction or fasting there is usually an acceleration of muscle protein degradation rates and reduction in muscle protein synthesis rates.

The maintenance or growth of muscle mass is going to be essential for several reasons, it is an important determinant of basal metabolic rate. A reduction in basal metabolic rate can have a major impact on total energy expenditure. This can promote weight gain and the risk of developing chronic diseases related to this weight gain. It also compromises strength and physical function.    

Intermittent fasting strategies should always be accompanied by a nutrition professional

According to scientific evidence, with adequate nutritional monitoring, lean body mass is generally maintained when intermittent fasting is combined with strength training is performed. However, it is not clear whether or not intermittent fasting inhibits the accumulation of lean mass depending on adequate protein supply and energy balance. What science has made clear is that intermittent fasting in combination with strength training can lead to a reduction in body fat even when there is a caloric surplus.

With all of the above we do not want to devalue the strategy of intermittent fasting or deny that it generates certain benefits to our health, but as long as there is adequate supervision, by a qualified professional in nutrition. Many times we tend to use dietary strategies on our own without any supervision, which can lead to negative consequences, such as those  mentioned above. In addition, it should always be individualized in each case and from one person to another this intermittent fasting strategy may vary or even be harmful.

Bibliography

Patterson, R. E., & Sears, D. D. (2017). Metabolic Effects of Intermittent Fasting. In Annual Review of Nutrition (Vol. 37, pp. 371–393). You can read the full article here.

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. In Nutrients (Vol. 11, Issue 10). You can read the full article here.

Saz-Peiro, P. (2017). Ayuno intermitente. Medicina Naturista, 11(January), 100. Welton, S., Minty, R., O´Driscoll, T., Willms, H., Poirier, D., Madden, S., & Kelly, L. (2020). Intermitten fasting and weight loss. Canadian Family Physician, 66, 117-125.