Researchers studied 80 boys who received treatment to slow down early puberty to see how it affected their weight. The treatment, called GnRHa, works by pausing the hormones that trigger puberty. The study found that weight changes during treatment depended on whether boys started out at a normal weight, overweight, or obese. Normal-weight boys gained some weight during treatment but lost it later as adults. Overweight and obese boys stayed about the same or actually lost weight. The findings suggest that all boys receiving this treatment should follow healthy eating and exercise plans, especially those who start at normal weight.

The Quick Take

  • What they studied: Whether a hormone treatment that slows early puberty in boys affects their body weight and weight gain patterns during and after treatment.
  • Who participated: 80 boys with early puberty (starting puberty too young) who received monthly hormone injections. The boys were grouped by their starting weight: 42.5% were normal weight, 30% were overweight, and 27.5% were obese. Researchers followed 58 of these boys into adulthood, about 7 years after treatment ended.
  • Key finding: Weight changes during treatment depended on starting weight. Normal-weight boys gained weight during the first year of treatment, but this extra weight went away by adulthood. Overweight and obese boys didn’t gain much weight during treatment, and obese boys actually lost weight. Adult weight was most strongly connected to starting weight before treatment began.
  • What it means for you: If a boy is prescribed this early puberty treatment, doctors should watch his weight carefully and recommend healthy eating and exercise from the start. This is especially important for normal-weight boys, who are more likely to gain weight during treatment. The good news is that weight gained during treatment may not stick around into adulthood.

The Research Details

This was a follow-up study where researchers tracked 80 boys with early puberty who received hormone treatment (leuprolide acetate injections every 4 weeks). They measured the boys’ height, weight, and body mass index (BMI) at the start of treatment, then every year during treatment, and finally when they reached their adult height—about 7 years after treatment ended. The researchers divided the boys into three groups based on their starting weight (normal, overweight, or obese) to see if weight changes were different depending on starting size.

The treatment works by using a synthetic hormone that tells the body to pause puberty. During normal puberty, the body naturally gains fat and muscle, especially in boys. By pausing puberty, this treatment might change how much weight boys gain. The researchers wanted to understand these weight changes both during treatment and years later as adults.

Fifty-eight of the original 80 boys were available for follow-up measurements in adulthood, which allowed the researchers to see the long-term effects of the treatment on adult weight.

Understanding how this treatment affects weight is important because doctors need to know what to expect and how to help families manage their child’s health during treatment. If the treatment causes weight gain, families should know this upfront so they can take steps to prevent unhealthy weight gain. This research helps doctors give better advice about diet and exercise during treatment.

This study followed real patients over many years, which is a strength because it shows what actually happens in practice. However, only 58 of 80 boys were available for adult follow-up, which means some information was lost. The study didn’t have a comparison group of boys who didn’t receive treatment, so we can’t be completely sure the treatment itself caused the weight changes versus other factors like normal growth. The study was conducted at one medical center, so results might be different in other populations or countries.

What the Results Show

During the first year of treatment, normal-weight boys gained weight (their BMI score increased from 0.5 to 1.2), but overweight and obese boys did not gain significant weight. By the second year of treatment, obese boys actually lost weight (their BMI score dropped from 2.3 to 1.7). Overall, when looking at all boys together, weight stayed relatively stable during the first two years of treatment but decreased by the time they reached adult height.

When researchers looked at the boys as adults (about 7 years after treatment ended), something interesting happened. The normal-weight boys who had gained weight during treatment lost that extra weight and returned to their starting weight. The overweight boys stayed about the same weight as before treatment. The obese boys kept the weight loss they had achieved during treatment.

The strongest predictor of adult weight was the boy’s weight before treatment started. Boys who were heavier before treatment tended to be heavier as adults, even though some weight changes occurred during treatment. This suggests that starting weight is the most important factor in determining adult weight, more so than the treatment itself.

The study found that different weight groups responded differently to the treatment. Normal-weight boys showed the most weight gain during the first year, suggesting they may be at higher risk for unwanted weight gain. Overweight boys remained stable during treatment. Obese boys actually benefited from weight loss during the second year of treatment. These different responses suggest that doctors should tailor their advice based on whether a boy starts at normal weight, overweight, or obese.

Previous research on this topic was limited and didn’t provide clear answers about how this treatment affects weight in boys. This study adds important information by following boys into adulthood and showing that weight changes during treatment don’t necessarily predict adult weight. The finding that normal-weight boys are at higher risk for weight gain during treatment is new and helpful for doctors planning care.

The study had several limitations that readers should know about. First, only 58 of the original 80 boys were followed into adulthood, so some information was lost. Second, the study didn’t include a comparison group of boys who didn’t receive treatment, making it harder to know if the treatment itself caused weight changes or if other factors were responsible. Third, the study was conducted at one medical center in one country, so results might be different in other places or populations. Finally, the researchers didn’t measure other important factors like diet, exercise, or family history of weight problems, which could have affected the results.

The Bottom Line

Boys starting this early puberty treatment should be counseled about the possibility of weight gain, especially if they start at normal weight. All families should be encouraged to follow healthy eating and regular physical activity plans from the beginning of treatment. Doctors should monitor weight regularly during treatment and adjust diet and exercise recommendations as needed. These recommendations are supported by the study findings but should be discussed with the child’s doctor based on individual circumstances.

This research is most relevant for boys diagnosed with early puberty who are considering or starting hormone treatment, and their families. Pediatricians and endocrinologists (hormone specialists) who treat early puberty should use this information when counseling families. Parents and boys should understand that weight changes during treatment are possible and manageable with healthy lifestyle choices. This research is less relevant for girls with early puberty, as the study only included boys, and the hormonal effects may be different.

Weight gain during treatment, if it occurs, typically happens in the first year. Weight loss or stabilization may occur in the second year and beyond. Any weight gained during treatment may take several years to resolve after treatment ends, though the study showed it often returns to normal by adulthood. Families should expect to see changes over months and years, not weeks.

Want to Apply This Research?

  • Track weight and BMI monthly during the first year of treatment, then every 3 months thereafter. Record alongside diet and exercise notes to identify patterns. Compare monthly measurements to the previous month to spot trends early.
  • Set specific, achievable goals like 30 minutes of physical activity 5 days per week and daily tracking of meals and snacks. Use the app to log healthy foods and water intake. Set reminders for meal times and activity breaks. For normal-weight boys especially, focus on preventing weight gain through balanced nutrition rather than restriction.
  • Create a long-term tracking dashboard showing weight trends over months and years. Set alerts if weight increases more than expected for age and height. Track lifestyle factors (exercise minutes, water intake, sleep) alongside weight to identify what helps maintain healthy weight. Continue monitoring for several years after treatment ends to ensure weight stabilizes appropriately.

This research describes what happened in a specific group of boys receiving early puberty treatment. Individual results may vary based on genetics, diet, exercise, and other health factors. This information is educational and should not replace advice from your child’s doctor. Before starting or changing any treatment, always consult with a pediatrician or endocrinologist who knows your child’s complete medical history. Weight changes during treatment should be monitored by healthcare professionals, and any concerns should be discussed with your medical team immediately.