10 Risks of Underfueling For Athletes

10 Risks of Underfueling For Athletes
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Athletes understand body composition and weight are closely related to athletic performance. Sports that demand a specific aesthetic, such as dance; have weight classes, such as wrestling; or are bodyweight driven, such as running and cycling, put more emphasis on achieving a lighter, leaner body. Power-to-weight ratios, range of motion and energy efficiencies are examples of areas where weight loss can be beneficial to athletic performance, but careful attention to nutrition and health needs should be considered when embarking on a mission for lower body weight.

Unfortunately, it’s common for athletes who start on the path of slight calorie restriction to begin to take things too far as they see the benefits of their weight loss. This spiral from healthful dietary control to serious food restriction and disordered eating tendencies happens quickly and often without awareness. A preoccupation with eating too little is a trap of short-term athletic performance benefits, versus long-term failing health.

Severely restricting calorie intake may eventually lead to some or all of the following negative conditions.



Probably the most common effect of eating too little for energy expenditure — and the one that confuses athletes the most — is stalled weight loss. At a certain point, athletes see they aren’t losing any additional weight as they continue to eat less and less. This is due to the body conserving enough fuel to cover demands of life and training. Typically, athletes who reach this weight-loss plateau see a resurgence in weight loss when they begin to adequately fuel the body.



Muscle mass is anabolic, meaning in a process of building — and building requires materials (food energy). By depriving the body of energy, you are risking a decrease in muscle mass and therefore will be unable to perform at the same power outputs.



When your body isn’t getting enough food, sleep suffers and the body goes into a type of hibernation attempting to not expend any additional energy. Being a good athlete is all about having ample energy to expend.



Restricting calories comes with consuming less vital nutrients (vitamins, minerals, phytonutrients) and puts your body at risk of many deficiency-related poor health outcomes. While supplements can help, they are contraindicated for replacing whole food sources.



This is a specific form of nutrient deficiency. When calcium isn’t coming into the body through calcium-rich foods, your body pulls it from your bones. This leaves your bones weak, brittle and at greater risk for fractures and breaks; two common injuries that take athletes away from training.



Training adaptations are made when the body is able to bounce back stronger after each session. It requires a large amount of energy (expended in the form of excess post-exercise oxygen consumption) to repair muscle tissues and restore your body’s normal resting state. When you’re depriving the body of fuel, it cannot use the energy it needs for this function.



Endurance athletes are at risk for upper respiratory infections during periods of heavy training and competition. Restricting intake complicates this further because it leads to a lack of antioxidants, vitamin C, zinc, copper and carbohydrates, which play vital roles in maintaining immune health.



Females who chronically avoid consuming adequate carbohydrates put their bodies at risk for potentially irreversible hormonal problems. Hormones play such a large and diverse role in the body’s health that these negative effects include poor bone health, irregular or absent menstruation, mood swings, sleep disturbances, fatigue, fertility issues and increased injury risk.



To limit the amount of energy being used, the body lowers heart rate and stroke volume. These effects are seen in individuals chronically consuming diets far below what the body needs, which puts an athlete at serious risk of sudden cardiac arrest.



Athletes get caught up in focusing on performance metrics over general health. In the short term, performance is typically increased when mass is reduced. However, as time goes on, poor dietary intake deteriorates health and limits what the body is capable of doing. Seeing stalled or decreasing performance results is a big indicator your diet is insufficient to match energy needs.

While females have long been the center of concern when it comes to underfueling, malnutrition and undereating are not just a female athlete problem. Current trends prove men in weight-dependent sports like cycling are just as prone to risky dietary behaviors as women. In fact, the classic ‘Female Athlete Triad,’ a condition relating poor energy balance to amenorrhea, low-bone density and underweight BMI, has been renamed to Relative Energy Deficiency in Sport (or Red-S), a broader, more gender-inclusive condition. Red-S encompasses all the above symptoms as they relate to low energy availability in athletes. Energy availability (EA) is a key metric in evaluating an athlete’s health and performance. EA is defined as caloric intake minus caloric output of training, divided by kilograms of fat-free body mass. To be able to cover all the energy lost training and all other metabolic processes, consistently low EA (less than 30cal/kg) puts an athlete at risk for the aforementioned conditions and ultimately crushes any chance of achieving goals and a stellar performance.


In some cases, losing weight may be necessary to improve health and get the extra edge you need to perform at a more competitive level. However, if losing weight is your goal, it should be approached in a strategic, slow and healthful way with ample support and assistance from a professional. If you’re concerned you might not be eating enough, seek a sports dietitian to help fine tune and optimize your dietary intake to meet your specific cycling performance goals while maintaining your health.

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