Intermittent Fasting: Is It Safe for Adolescents?

Intermittent fasting is an advisable way for adolescents to lose weight, as long as they meet their health professional's conditions.
Intermittent Fasting: Is It Safe for Adolescents?

Last update: 09 May, 2023

Intermittent fasting has become popular as an effective weight loss technique. But is it safe for teenagers? This is something to stop and think about, as science doesn’t have enough evidence to support one answer or the other. Therefore, I’ll also offer my professional opinion.

It’s normal for a teenager to require more nutrients to cope with the accelerated increase in size and weight, in addition to other body changes. Therefore, you have to eat what’s right and not limit nutrients for very long periods of time. But what if you want to lose weight, can you use intermittent fasting safely? Keep reading and you¿ll find the answer.

What is intermittent fasting?

Fasting has been practiced for religious purposes throughout history. But for dietary purposes, intermittent fasting (IF) is defined as an eating pattern that consists of extending certain spaces or windows of our day in which we don’t eat. Therefore, meals are concentrated in fewer hours per day.

For example, you can do a 12-hour fast and eat in the following 12 hours; a 16-hour fast, and then eat for 8 hours; and even a 20-hour fast and 4 hours to eat. Also, there are 24-hour fasts and 48-hour fasts. As you can see, intermittent fasting isn’t a diet per se, but a protocol for eating during the day. It’s a scheme that changes the shape of metabolism in our body.

During fasting hours, insulin, which is responsible for carrying sugar as a source of energy to the cells, lowers its levels in the blood. Therefore, the body uses fat deposits to obtain the energy it needs. This results in imminent weight loss. In addition, intermittent fasting is also related to the prevention of certain diseases. However, everything will depend on the characteristics of the person and their general conditions.

Are there risks involved in intermittent fasting?

“Not everything that glitters is gold,” because despite the benefits of this eating pattern, you can also run some risks. In this regard, there are some doubts about whether it’s a safe and effective long-term method for weight control. So says a review published in the journal Behavioral Science.

The short- and medium-term risks so far are as follows:

  • Anxiety: When many hours go by without eating, anxiety and stress can be generated. As a result, binge eating may appear. Then, a feeling of guilt occurs and people stop eating during the feeding windows. That’s to say, the protocol is completely lost.
  • Digestive disorders: Gastritis or acidity appear when the fasting window is very long.
  • Imbalance in nutrient intake: Intermittent fasting doesn’t indicate what you should eat, but when. As a result, foods that don’t provide vitamins or minerals may be included, which can lead to nutritional imbalances.
A woman eating a plate of vegetables, cheese, and eggs.
When performing intermittent fasting, it’s essential to have good guidance from a professional. Otherwise, you run the risk of including foods that are harmful to your health.

Is intermittent fasting safe for teenagers?

The popularity of intermittent fasting for weight loss has reached social networks and the ears of teenagers who are concerned about their body image. Therefore, many adopt it as an eating style in order to look better. However, so far, there are some contradictions regarding its safety. Below, we’ll tell you the different positions on the matter:

Those who don’t support intermittent fasting in teens

Science shows a study recorded in the journal Eating Behavior, in 2022, which highlights the emergence of a dangerous behavior already known in adolescents. Intermittent fasting could enhance eating disorders, such as binge eating, vomiting, and compulsive exercise. In this study, there’s also a reflexive call to professionals not to indicate intermittent fasting to adolescents to lose weight. In this regard, another reason is the arrival of puberty, as biological, emotional, and cognitive changes appear with accelerated physical growth. And for them to occur in a healthy way, a lot of energy and nutrients are needed.

Those who support it

There are several scientific studies that support intermittent fasting in adolescents with obesity. One study that evaluated its feasibility, efficacy, and acceptability found a significant reduction in body composition and cardiovascular disease risk. At the same time, a research project suggested intermittent fasting as the dietary intervention of choice in obese adolescents.

Also, a 2023 review appearing in the Journal of Yeugnam Medical Science highlights the effectiveness and acceptability of intermittent fasting in obese adolescents.

The professional opinion

Intermittent fasting can be safe in older adolescents if monitored and planned by a physician or nutritionist. In turn, the support of the psychologist is also important. In addition, other factors to consider are that it’s only indicated in cases of obesity and excess weight. Also, when the young person has passed the puberty stage, that is, between 16 and 18 years of age. Another factor to take care of is the diet.

For this, it’s important that the eating window be healthy, conscious, balanced, and varied. Healthy lifestyle changes should be encouraged throughout the process, including regular exercise, good sleep, and stress management.

A teenage girl feeling dizzy.
In general, adolescents are a bit more sensitive to fasting. For example, fasting can cause excessive tiredness, weakness, lack of concentration, stunted growth, and interruption of menstruation in the case of females.

When not to recommend it?

Intermittent fasting isn’t recommended for adolescents in the following cases:

  • The physician doesn’t recommend it
  • The child has a history of eating disorders
  • When they don’t eat enough and skip meals
  • They’re not aware of the benefits and consequences of intermittent fasting
  • They have other associated health problems
  • They’re underweight for their age and height
  • The child takes medication
  • Pregnancy or breastfeeding

If none of the above apply, then the 16/8 method is planned, as it has a wide window. However, in the first week, it’s possible to start with the 12 or 10-hour meal plan. At the same time, the body adapts and the specialist evaluates if the method is suitable for the young person. Fruits, whole grains, olive oil, nuts, dried fruits, legumes, vegetables, and lean animal proteins should be included as part of the diet.

Undoubtedly, intermittent fasting is not recommended for children. There are plenty of reasons for this. Especially because of the high energy and nutrient requirements necessary to form the tissues and molecules involved in physical, neurological, and physiological growth, and development in general.

Yes, as long as it’s for weight loss and the conditions imposed by health professionals are met. In particular, in terms of age and the absence of eating disorders and other diseases. The entire protocol must be strictly monitored by the treating physician, nutritionist, and psychologist.

Those adolescents who are still in the process of puberty shouldn’t perform intermittent fasting for weight loss. For older teens, the recommended fasting is 16:8, as it’s required to widen the diet window. It should be framed within a healthy, conscious, balanced, and varied plan. A change in eating style, exercise, stress management, and good sleep will be essential for the success of the plan.

In addition, food education at home and in schools is a powerful tool to prevent weight gain in adolescents. It’s key to encourage good eating habits and a healthier lifestyle.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Ganson, K. T., Cuccolo, K., Hallward, L., & Nagata, J. M. (2022). Intermittent fasting: Describing engagement and associations with eating disorder behaviors and psychopathology among Canadian adolescents and young adults. Eating behaviors47, 101681.
  • Harvie, M., & Howell, A. (2017). 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. Behavioral sciences (Basel, Switzerland)7(1), 4.
  • Jebeile, H., Gow, M. L., Lister, N. B., Mosalman Haghighi, M., Ayer, J., Cowell, C. T., Baur, L. A., & Garnett, S. P. (2019). Intermittent Energy Restriction Is a Feasible, Effective, and Acceptable Intervention to Treat Adolescents with Obesity. The Journal of nutrition149(7), 1189–1197.
  • Song, D. K., & Kim, Y. W. (2023). Beneficial effects of intermittent fasting: a narrative review. Journal of Yeungnam medical science40(1), 4–11.
  • Vidmar, A. P., Goran, M. I., Naguib, M., Fink, C., Wee, C. P., Hegedus, E., Lopez, K., Gonzalez, J., & Raymond, J. K. (2020). Time limited eating in adolescents with obesity (time LEAd): Study protocol. Contemporary clinical trials95, 106082.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.