The Endurance Dietitian: Why Runners Shouldn’t Go Fat-Free

By Kim McDevitt, MPH RD on June 24, 2015 , categorized in Endurance

Welcome to The Endurance Dietitian! If you’re like me, and define a large portion of your life with training plans, run clubs, “long-run-Sundays,” and chasing PRs, you’re in the right place. It seems daily we’re reading about the next best ingredient or trend we should be including into our running lifestyle. I’m here to share my passion for sports nutrition by breaking down the technical jargon of the current trends, weeding through the research and explaining what you need to know. Think of this as our runner girl talk (don’t worry—boys can still eavesdrop).

There was a period of time, not too long ago, that I classify as the “fat-free craze.” Everything from ice cream to peanut butter was getting stripped of fat in attempt to make you both thinner and stronger.

Thankfully, since this craze there has been a turn of events and people are increasingly learning that there is a place for fat in the diet, especially the athlete’s diet.

There’s a direct link found between dietary fat and hormone levels in the body. As runners we compromise our body’s ability to adequately produce hormones at the correct level daily, which makes it even more critical for us to replenish our bodies with the correct nutrients.

The Hormone- Fat Link: Estrogen

When body fat is too low, the female body is unable to produce enough estrogen. Without adequate estrogen levels women will stop menstruating monthly, as well as put themselves at risk for osteoporosis and overall low bone density.

As runners we rely on our bones to support a healthy racing body. Poor bone health manifests in runners as stress fractures and broken bones, and typically is the result of high cortisol and low estrogen in the body.

Here’s how it works: When the body is put through high levels of stress—either through work, lifestyle or exercise, or a combination of the three–the adrenal glands release the stress hormone cortisol. When there’s chronic stress in the body the adrenal glands over produce cortisol, which not only disrupts immune health, blood pressure, and more, but also prevents estrogen and testosterone from functioning properly. When you have low estrogen levels combined with high cortisol the result becomes loss of bone density1Rolfes, Sharon Rady, et.al. (2009). Understanding Normal and Clinical Nutrition. Wadsworth Cenage Learning. Eighth Edition..

Research shows that diets with adequate levels of fat increase the amount of estrogens in the blood. In fact, when women adapt a low-fat diet, their estrogen levels noticeably drop in a very short time2Herber D. et al. (1991). Reduction  of serum estradiol in postmenopausal women given free access to low-fat high-carbohydrate diet. Department of Medicine, University of California, School of Medicine, Los Angeles 90024-1742..

The Hormone-Fat link: Testosterone

Testosterone is also influenced by stress, excess cortisol and plays a critical role in the brain and body of the athlete.

Testosterone affects muscle tissue, specifically by promoting growth hormone responses in the pituitary gland, which in turn influences protein synthesis in muscles. Free testosterone in the body also helps with muscle growth, tissue repair and immune system strength3Dorgan JF, et al. (1996) Effects of dietary fat and fiber on plasma and urine androgens and estrogens in men: a controlled feeding study American Journal of Clinical Nutrition. 64(6):850-5. Accessed on 5/13/15 from http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=8942407.

Research shows that testosterone levels tend to be higher in those who include saturated fats in the diet4Kraemaer WJ, et al. (1997) Testosterone and Cortisol in relationship to dietary nutrients and resistance exercise. Journal of Applied Physiology. 82(1): 49-54. Accessed on 5/13/15 from http://jap.physiology.org/cgi/pmidlookup?view=long&pmid=9029197. Which means, yes, you need not only fat but also some forms of saturated fat in your diet. Keep reading for specific recommendations!

The fats to focus on

It’s important to make sure you’re eating enough calories each day to support your running. Aim to get your calories from whole food sources, with 20% to 30% coming from fats.  Focus on healthy fats, including Omega-3s and monounsaturated fats as well as select saturated fats.

  • Omega-3s: Otherwise known as alpha-linolenic acids or ALA, omega-3s are essential fatty acids, which means they are literally essential to the body and must be obtained through the diet (your body can’t make them). EPA and DHA are the derivatives of Omega-3s and are critical to the body for everything from heart health, to managing inflammation, and reducing the risk of heart disease.

Get your Omega-3s from plant based sources such as chia seeds, hemp seeds, and walnuts.

  • Monounsaturated fats: this type of fat is best known for positively influencing cholesterol in the body. These fats are proven to lower bad cholesterol levels in the body while raising good cholesterol levels, thus having a positive role in reducing cardiovascular disease.

Good sources of monounsaturated fats include avocado, olives, olive oil, almonds, pumpkin seeds and sesame seeds.

Saturated fats: While saturated fats have been given a bad name when it comes to health and diet, certain saturated fats can be good for you. The saturated fat that can be beneficial to the diet are medium chain fatty acids (versus short-chain fatty acids), which are found in coconuts. The fat absorbed from coconut is not stored in the body but rather used immediately for energy.

What types of healthy fats are you incorporating into your daily meals?

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diet fads diet trends Fat-free food fads food trends hormones runner running women's health

Kim McDevitt, MPH RD

Kim McDevitt works at Vega as a National Educator. A runner, cooking enthusiast, plant-focused flexitarian, Kim has passionately built her career in nutrition. Noticing that her running performances were closely tied to what she was eating, Kim decided to study nutrition and pursue advanced degrees in Dietetics and Public Health, to better understand the power of food in performance. Today, Kim specializes in sports nutrition to enhance athletic performance and focuses on realistic and approachable ways for improving health through educated dietary choices within an active lifestyle.

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