Meals for Miles

Two weeks are all that is left between myself and NEVER HAVING TO DO HOMEWORK OR GO TO CLASS AGAIN EVER IN LIFE. Oh God, it feels good to say that. And I’m also in pretty good shape when it comes to final assignments, the main one being my sports nutrition research project. A lot of you took my survey (thank you!), and I’m pretty much done tallying, analyzing and writing the paper.

Obviously I love sports nutrition, and one topic I have a keen interest in is lady athletes and menstruation (if you’re one of the maybe three dudes who reads this blog, sorry but this has little to do with you!). A lot of female athletes – especially endurance athletes like runners – experience menstrual irregularities, which can range from skipping a period here and there to complete absence of a menstrual period (called amenorrhea). This may not seem like a big deal, or even a good thing (no tampons! no cramps!), but the truth is not having a period isn’t normal. It not only means you will have trouble conceiving when and if you want to, but also puts you at a higher risk for things like fractures and osteoporosis.

There are many theories as to why athletes have problems with their periods – low body fat and eating disorders being the top two – but I’ve always wondered whether there is more to the story. Very lean professional athletes have successfully gotten knocked up and had kids, and some regular everyday athletes haven’t had a period in years.

Biologically, low estrogen levels are what cause athletes to miss their periods. Sometimes they are put on the birth control pill to increase estrogen levels and restore menstruation, but it is basically like putting a bandaid on the problem and not really fixing the underlying issue. This is why I excluded you from the survey if you answered “yes” to the question about oral contraceptives.

I’ve always been curious as to whether dietary fat can positively influence estrogen levels since some of our body’s estrogen is made in fat cells. It has been shown in a number of studies that reducing fat intake can lower estrogen levels in overweight women at risk for breast cancer. SO, if reducing fat intake can lower estrogen levels, then can increasing fat intake raise estrogen levels? Or is it really more about overall body weight/body fat? That was basically my research question, but because I obviously couldn’t test estrogen levels in my subjects I aimed to see whether there was a difference in animal fat intake among the people who said they had irregular or no periods and those who said they had normal periods.

animal fat can be delicious

I present the results next week (spoiler alert?), but in a nutshell I didn’t find any significant difference in animal fat intake among all of the people who took the survey. Kind of a bummer, but the sample size was pretty small and there are a bunch of other limitations to my “study.” I did find that the ladies who reported having no periods or irregular periods had a significantly lower body weight that the ladies with regular periods. This is pretty consistent with other research, which suggests that increasing overall energy intake (eating more calories) and gaining a little weight (~5 lbs or more) can restore menstruation in those who don’t have periods.

If we consistently don’t eat enough calories to replace what we burn through all of the miles we run, the body goes into something like “emergency mode” and the reproductive cycle is one of the first things to shut down because it’s not considered essential. But this doesn’t have to mean we are consciously starving ourselves (although this obviously is the case sometimes as well). One of the most interesting things I learned from reading through the research is that it’s possible to maintain a normal weight while at the same time be in a chronic energy deficient state. Sometimes we don’t know we’re not eating enough. Missing a period here and there (or every month) is a red flag to take a look at the bigger picture and make sure you’re getting enough calories. Here’s a cool formula I found from a recent Running Times article written by an RD/elite runner:

Women formula:

Step 1: Predicted Daily Energy Expenditure =

(10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161 = base number of calories

Step 2: multiple your base number of calories by an activity factor based on how active you are throughout the day. Don’t count running/working out. Activity factors can range from 1.4 – 2.5 or more, 1.4 being extremely sedentary. If you work in an office job, I would pick 1.4-1.6.

base number of calories x activity factor = total calories (not counting running)

Step 3: Here’s where you add in calories burned from running. Take the number of miles you run per week, multiply by 90 (an average amount of calories burned per mile) and divide by 7 to account for the seven days of the week.

#miles run x 90/7 = additional number of calories

Total calories + additional calories from running = daily caloric goal

Here’s an example for me assuming I am running 45 miles per week (to get your weight in kg divide pounds by 2.2; to get your height in cm multiply inches by 2.54):

(10x 58kg) + (6.25 x 167.6) – (5 x 30) – 161 = 1317

1317 x 1.6 = 2107

45 miles x 90 = 4050/7 = 579 + 2107 = 2686 total calories needed per day

When I did that I was pretty surprised at how high the number was, and while it’s probably not 100% accurate all of the time, it definitely prompted me to make a few changes to my diet.

Ok, whew. This was kind of a long one. As always, I’m curious to hear your thoughts on any of the above, and thanks again for taking the survey