This page exists for parents searching about teenagers and intermittent fasting. The short answer: don’t. Intermittent fasting is not appropriate for adolescents in almost any context. The longer answer is more nuanced, and worth understanding because teenagers are seeing fasting content constantly online and may already be experimenting.
This guide covers why fasting is not recommended for teens, the specific risks (especially the eating disorder risk), what to do if your teenager wants to fast, and the difference between sensible meal patterns and structured fasting practice.
Table of Contents
Why Fasting Is Not Recommended for Teens
Major medical organisations (including the American Academy of Pediatrics, the British Dietetic Association, and the Royal College of Paediatrics and Child Health) consistently recommend against intermittent fasting for adolescents. The reasons:
- Adolescent caloric and nutrient needs are elevated for growth and development
- Meal-skipping patterns are associated with increased risk of disordered eating
- Adolescent brains are particularly vulnerable to developing rigid eating patterns that persist into adulthood
- The metabolic benefits of fasting are not needed in healthy adolescents
- No evidence supports specific benefits of fasting for teens
- Multiple potential harms with no clear benefit
The Growth and Development Issue
The adolescent body is doing significant developmental work:
- Growth in height (continues until late teens for most)
- Bone density accumulation (peak bone mass is reached in early 20s; under-feeding now affects lifelong bone health)
- Muscle mass development
- Brain development continues into the mid-20s
- Sexual maturation and reproductive system development
- Metabolic system maturation
All of this requires consistent caloric and nutrient intake. Compressed eating windows tend to reduce overall intake even when not intended to. The cost of getting this wrong during development can be lasting — particularly for bone density, where peak mass is achieved in adolescence and not really recoverable later.
The Eating Disorder Risk
This is the most important section. Eating disorders most commonly emerge in adolescence and early adulthood. The combination of:
- Body image pressure
- Social media exposure to diet/wellness content
- The rigid structure of fasting protocols
- The reward of feeling “in control” of eating
- Adolescent brain plasticity
...creates substantial risk. Multiple studies show meal-skipping patterns in adolescents are associated with increased eating disorder development. Intermittent fasting often functions as a socially acceptable framing for restriction that wouldn’t otherwise be tolerated.
For an adolescent already struggling with body image or showing any disordered eating signs, fasting can be the structure within which a full-blown eating disorder develops. This is not theoretical — clinicians treating eating disorders see this pattern frequently.
The Few Exceptions
Some clinical contexts may involve fasting in adolescents under specialist supervision:
- Severe obesity with comorbidities, under endocrinology and dietitian supervision
- Type 2 diabetes management in collaboration with paediatric endocrinology
- Specific religious fasting traditions, with appropriate accommodations
- Pre-procedural fasting for medical procedures
None of these are appropriate for self-directed fasting based on internet content. They involve specialist medical oversight specifically because the risks in adolescents are higher.
What to Do If Your Teenager Wants to Fast
The conversation matters more than the rule.
Listen first
Why does your teenager want to fast? Common reasons: weight concern, social media exposure, peer influence, curiosity about a trend, performance goals (athletes), or — concerning — already-developing disordered eating thoughts.
The reason behind the request shapes the response. Curiosity about a trend is different from active body-image distress.
Don’t make food the battleground
Strict prohibitions can backfire by creating secret eating patterns. The goal is open conversation about why fasting isn’t the right tool for this stage of life.
Address the underlying concern
If body image is the issue, that’s the conversation to have — with possible professional support. If athletic performance is the goal, sports nutrition guidance for adolescents is a better path. If health curiosity is the driver, age-appropriate health information helps.
Discuss with your paediatrician
Particularly if your teenager is persistent about fasting, has lost weight recently, or shows other concerning eating patterns. Paediatricians screen for eating disorders and can refer if needed.
Watch for warning signs
(See section below.) Adolescent eating disorders are most treatable when caught early. Don’t dismiss early signs as “just being a teenager.”
Sensible Meal Patterns vs Structured Fasting
It’s reasonable for a teenager not to eat snacks late at night, to skip a snack they’re not hungry for, or to have a 12-hour overnight gap between dinner and breakfast. None of this is “intermittent fasting” in the structured sense.
The difference between healthy meal patterns and structured fasting:
- Healthy: “I’m not hungry for breakfast today, I’ll have a bigger lunch.”
- Healthy: “I don’t feel like a snack right now.”
- Concerning: “I’m doing 16:8, I can’t eat until noon.”
- Concerning: “I’m skipping breakfast every day to lose weight.”
- Concerning: Tracking fasting hours, using fasting apps, having strict rules about when food is allowed
The structure is the issue. Flexible eating patterns are healthy; rigid eating rules in adolescents are warning signs.
Warning Signs to Take Seriously
- Increasing rigidity around food choices
- Skipping family meals
- New focus on calorie counting or food tracking apps
- Weight loss in a teen who shouldn’t be losing weight
- Loss of menstrual periods (in girls)
- Excessive exercise alongside reduced eating
- Distress when eating patterns are disrupted
- Hiding eating or hiding not-eating
- Body image preoccupation
- Mood changes alongside food changes
- Loss of social activities involving food
Any of these warrant a conversation with your paediatrician. Multiple of these warrant urgency.
Frequently Asked Questions
My teenager just wants to skip breakfast. Is that fasting?
Not really. Many teenagers naturally aren’t hungry in the morning. Skipping breakfast occasionally because of low appetite is different from structured fasting. Watch the pattern: if it’s flexible and they eat well at other times, probably fine. If it’s rule-based and weight-loss-motivated, more concerning.
What about a teen athlete using intermittent fasting?
Adolescent athletes have particularly high caloric and nutrient needs. Intermittent fasting tends to produce inadvertent under-fueling, which impairs performance and recovery and increases injury risk. Sports nutrition for adolescents is a specialist area; generic adult fasting advice is not appropriate.
My teen has type 2 diabetes. Should they fast?
Only under paediatric endocrinology supervision. Adolescent type 2 diabetes is increasingly common; some specialised programs do use modified fasting protocols, but always with professional management.
What about religious fasting?
Religious fasting traditions vary, and many have specific accommodations for adolescents (shorter durations, partial fasts, exemptions). Generally compatible with adolescent health when traditions are followed thoughtfully and with attention to nutritional adequacy outside fasting times.
I fast and my teen is asking about it. What do I say?
Honest framing: “Adult bodies have already finished growing; teenage bodies are still building bone, muscle, and brain. Fasting can interfere with that. When you’re an adult and your body is fully developed, this could be an option. Right now, eating consistently supports the growth that’s happening.”
What if my teen has already started fasting?
Don’t panic; do open the conversation. Ask why, listen carefully, watch for warning signs of disordered eating. Discuss with paediatrician if pattern persists or if any concerning signs are present. If clear eating disorder behaviour is present, don’t wait — early intervention dramatically improves outcomes.
The Bottom Line
Intermittent fasting is not appropriate for teenagers. The growth, development, and eating-disorder-vulnerability factors all argue against it, and there are no demonstrated benefits to offset the risks. If your teenager wants to fast, the conversation matters: listen for the underlying motivation, address it with appropriate tools (body-image conversation, sports nutrition guidance, age-appropriate health information), watch for warning signs of disordered eating, and involve your paediatrician if concerning patterns develop. Healthy flexible eating throughout the day, with three regular meals and reasonable snacks, is what supports adolescent development.