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Why Athletes Shouldn’t Eat a Fat-Free Diet

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Why Athletes Shouldn’t Eat a Fat-Free Diet

There was a period of time, not too long ago, where everything from ice cream to peanut butter was getting stripped of fat in an attempt to make all sorts of foods “fat-free”. Thankfully, since that time 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 an association between dietary fat and hormone levels in the body. Heavy training can compromise 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.

Fat-Free Foods Affect Our Bodies’ Hormones

How Low-Fat Diets Affect Hormones

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 overproduce 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 mineral density.1

Low-Fat Effects on 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 low bone mineral density and weak bones

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

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 time.2

Low-Fat Effects on 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.

Healthy Fats to Include in Your Diet

It’s important to make sure you’re eating enough calories each day to support your exercise. Aim to get your calories from whole food sources, with 20% to 30% coming from fats.  Focus on good fats including  monounsaturated fats and polyunsaturated fat that includes Omega-3 ALA fatty acids. And these can be beneficial to have in the diet because, among other things, dietary fat helps with the absorption of fat soluble vitamins, vitamin A,D, E and K.3

Foods with this type of fat include olive oil, sesame oil, avocado and peanut butter. Omega-3 ALA cannot be made in the body, therefore you must get it from your diet. Omega-3 ALA can convert into different types of fatty acids once in your body (DHA and EPA). Plant based sources of ALA include walnuts, flax, chia seeds and hemp seeds.4

Looking to learn more about healthy fats?  Learn about the importance of fats and what fat-free foods to avoid or understand how to read a food label to empower yourself to make informed purchases.




  1. Rolfes, Sharon Rady, et.al. (2009). Understanding Normal and Clinical Nutrition. Wadsworth Cenage Learning. Eighth Edition
  2. Herber 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..
  3. National Institute of Health (2011). Weighing in on Dietary Fats. Accessed on 7/26/16 from: https://newsinhealth.nih.gov/issue/dec2011/feature1
  4. Dietary Guidelines for Americans 2016-2020 http://health.gov/dietaryguidelines/2015/guidelines/chapter-1/a-closer-look-inside-healthy-eating-patterns/#callout-dietary-fats


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