Is My Daughter At Risk Of Getting Her First Period Early?

Over the last several decades, we have seen the average age of first period (called menarche) decrease by 1-2 years.  The prevalence of girls in USA having early menarche (before age 11) has also increased from 2.6-4.6% to 6.6-12.2% over the last 60 years.  Understanding why periods are starting earlier is important as it can be distressing for these young girls, and is also associated with a higher long term risk of breast cancer, depression, and metabolic risk factors including type 2 diabetes and obesity.

While some of the trend towards earlier periods over the last several decades is due to better health and living conditions, it is also increasingly recognized that environmental factors including weight gain in pregnancy and energy availability during fetal life and early childhood may play an important role. 

A recent review published in Obesity Reviews summarizes the currently available data on this topic.  While it reveals that the literature on this topic is complex, challenging to interpret, and even contradictory at times, the overarching conclusions were that there may be a higher risk of a girl having an early first period when her birth weight is lower, and with higher body weight and weight gain in in infancy and childhood. 

So why would energy availability/energy stores have an influence on age of first period? Here are some possible links:

1. Leptin, which is a signal of energy availability produced by fat tissue, is elevated in obesity, and also in children with low birth weight experiencing catch up growth. Leptin is thought to be necessary for the onset of puberty, so higher leptin may stimulate earlier puberty.

2. Fat tissue converts testosterone to estrogen (and vice versa). Rapid weight gain and childhood obesity is associated with greater production of testosterone derivatives from the adrenal glands, so there may be more of this testosterone available to convert to estrogen in fat tissue, contributing to an earlier first period.

3. Increased insulin levels (as seen in obesity) may advance sexual maturation; in fact, there is some evidence that metformin, a diabetes medication that lowers insulin resistance, may delay onset of periods in low-birth-weight girls with early onset of puberty.

4. Genes have been discovered to be associated with both obesity and age of first period, suggesting there may be some common genetic threads here too.

Also interesting: 

5. Nutritional factors. Breast feeding, and higher intake of plant proteins and fibre may be protective of excessive weight gain and thus protect against earlier periods.  Formula feeding and high intake of cow’s milk and animal protein is associated with an earlier first period (possibly by stimulation of IGF-1 secretion, thus triggering earlier growth).  Higher sugary beverage consumption is also associated with earlier periods, independent of body mass index (BMI).

6. Chemicals in our environment that mess with our hormone systems (called endocrine disruptors) may modify age of first period directly (by modulating hormone responsiveness, epigenetic effects, or stimulating maturation directly), or indirectly by increasing the risk of childhood obesity.

So, it seems that prenatal life, infancy and childhood may present opportunities to improve overall health, and thereby possibly prevent early onset of menstrual periods.  This includes:

• Ensuring appropriate nutritional status of mom while pregnant
• Watching for suboptimal fetal growth (and managing appropriately depending on cause)
• Watching for, and managing, excessive weight gain in childhood
• Watching for signs of early pubertal development and intervening where appropriate with lifestyle/weight management strategies.  I would be very curious to hear from my pediatric colleagues whether they are using metformin in this scenario – please contribute your comments at the end of this blog post!

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2017

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What Does It Take To Keep Weight Off 6 Years Later?

Understatement: The Biggest Loser is not my favorite show. 

However, the National Institute of Health took this opportunity to learn some things about metabolism after weight loss, and to determine whether changes in food intake or physical activity are associated with keeping the weight off vs regaining weight over the long term.

In a previous blog, we talked about the finding from The Biggest Loser contestants that 6 years after losing weight on the show,  there was about a 500 calorie lower daily calorie burn than what would be expected at their weight 6 years later, which helps to explain why it is so hard to keep weight off after weight loss.

In the most recent publication, we learn that people who were able to keep weight off 6 years after being on The Biggest Loser had higher daily physical activity levels than those who experienced weight regain.  Specifically, those who maintained a weight loss of 25% had increased their physical activity by 160% compared to the start of the study, whereas those who weighed more than they did at the start of the study had increased their physical activity by 'only' 34% (not enough to offset the decrease in metabolism that happens after weight loss). 

Energy intake at 6 years after the show was estimated to be similar between those who maintained weight loss (8.7% less than before the study) vs those who regained weight (still 7.4% less than before the study!). (Scientists: daily energy intake was assumed to be equal to total daily energy expenditure, as weight was reported as stable both at the start of the show, and at the 6 year mark.)

Previous studies such as the LOOK AHEAD study and the National Weight Control Registry have also suggested that people who are able to keep weight off are those who do more physical activity after weight loss, but in these studies, physical activity was self reported (and we know from other studies that physical activity is over reported).  The current study is the first to use the gold standard of doubly labeled water to measure changes in physical activity several years after weight loss.

Bottom Line: While we know that physical activity is not as important for achieving weight loss, the evidence points to physical activity being very important for maintaining weight lost over the long term.

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2017

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