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Myth Buster Monday: Low-fat Diets & Fat-Burning Zones for Athletes

By: Alexa McDonald, RD, CDN


Fat is an essential fuel for our bodies.  Although low fat diets were all the hype in the 90’s, they compromise both health and performance.  In fact, no evidence has been found for improvement in performance with fat intake of less than 20%. Instead, inadequate stores and intake affect bone health and even reduce testosterone levels decreasing muscle mass and strength.  In addition to keeping the body strong and healthy, fat works as a concentrated-calorie source to fuel exercise and keep athletes fuller for longer.  In the case of fat, too much of a good thing is definitely a thing.  High fat intakes, even when healthy, can result in a higher calorie intakes and ultimately weight gain if calories in is greater than calories out.  No matter who the athlete or what the exercise, proper fat intake is an important part of training and weight control.


As the intensity of aerobic exercise increases, the percentage of fat burned decreases, increasing the use of carbohydrates.  Studies found that peak fat-burning occurs at 68-79% heart rate max. However, at intensities higher than this, our bodies actually work harder and ultimately burn more calories and more fat.  With these points in mind, a “fat burning zone” may exist, but may not make that much difference in the scheme of things.  Yet, there still may be hope for this myth.  Regular aerobic activity actually increases the body’s ability to burn fat, making a fat burning zone more about frequency than intensity.  



Ah, the question every dietitian hears almost daily.  Fat intake intake is recommended at 20-35% of daily calorie intake.  For an estimate, multiply weight in pounds by 0.45 for an average recommendation of grams of fat per day.

Less than 10% of your total calories should be from saturated fats, such as bacon, butter, cream cheese, and trans fats should be avoided completely.  The majority of intake, at least 20% of calories, should come from “good” fats, such as olive oil, fatty fish, nuts/nut butters, seeds, and fatty fish, like salmon and mackeral.  

Keep these tips in mind:

  • Fat contributes the most calories per gram; make sure your fat choices are smart (“good fats”), in moderation, and worth the extra calories for your body.  
  • High fat meals should be eaten at least 4 hours before exercise to allow proper digestion and a comfortable more effective workout
  • Intake of Omega-3’s and 6’s should be monitored, especially if you’re eating less than 6 ounces of fish per week.  


Alexa McDonald

Alexa McDonald, RD, CDN is a Registered Dietitian-Nutritionist (RDN), 200 Hour RYT Certified Yoga Instructor, and owner of Expert Nutrition & Wellness (ENW) based out of Hoboken & Edgewater, NJ. After obtaining her Bachelor’s degree in Dietetics from the University of Maryland, College Park, Alexa went on to complete her dietetic internship and obtain her Masters of Science in Foods & Nutrition from New York University. With experience in both clinical and foodservice settings, she works with clients to meet their individual health goals in the areas of Medical Nutrition Therapy, sports nutrition, eating disorders, weight management, and food allergies. In addition to nutrition services, she also provides both group and individual yoga instruction. As an avid runner and self-proclaimed foodie, Alexa is most often praised by her clients for her ability to “fit in the good stuff." Her personal and company mission is to assist clients, teams, and families in creating a balance between eating healthy and enjoying life, while giving them the tools to accomplish their health and fitness goals. In 2016, she is excited to complete her Certified Specialist in Sports Dietetics (CSSD) certification and work with new clients that challenge and teach her everyday. Follow her on Twitter and Instagram @BeBalanacedRD or email her at

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