Rarely does someone seek my professional help to ensure that they are eating enough. Most athletes are more concerned about nutrition in the context of recovery, enhanced performance or reaching an ideal body weight. However, underfuelling should be a huge concern for athletes because the negative consequences of underfuelling are without a doubt more detrimental than overfuelling.

Underfuelling means not eating enough calories to cover the calories burnt through exercise plus the calories for just being a human. Don’t forget that our bodies require energy even when we’re not doing anything. Energy is required for your heart to beat, for your lungs to breathe and even to think. Even if you slept all day, you would still require energy. If you don’t eat enough, there are metabolic and hormonal changes that occur. These detrimental changes occur in both female and male athletes.

The consequences of not eating enough go beyond the risk of nutrient deficiencies such as iron deficiency or being chronically fatigued. For instance, underfuelling can cause a negative change in lipid profile and endothelial dysfunction, which increases cardiovascular risk. That’s right, you may be exercising to improve your heart health, but if you’re underfuelling, you could actually be increasing your cardiovascular risk. Need even more convincing that underfuelling is worse than overfuelling? Read on for other hormonal and metabolic changes that occur:

1. Reduced metabolic rate
I often have athletes come to me who are concerned because their weight is stable despite eating very little and exercising a lot. Eating less calories than you require does not magically result in weight loss. The body responds to calorie restrictions by decreasing resting metabolic rate and increasing body fat stores. Our bodies are smart and if we’re not fuelling them properly, they’re able to make changes that reduce the amount of calories we require rather than changing our weight.

2. Increased injury risk
Underfuelling significantly increases your risk of injury. The hormonal changes that can occur if you don’t eat enough reduce bone density. This not only increases risk of osteoporosis, but also puts athletes at a significantly higher risk of a stress fracture. Beyond bone health, exercising with low glycogen stores increases risk of injury and if you’re not properly refuelling post-exercise, you’re not going to recover as well. If you want to stay injury free, eating enough it vital.

3. Decreased athletic performance
What athlete doesn’t want to perform at their best? Not eating enough impairs athletic performance and will prevent you from reaching your full potential. Underfuelling decreases muscle strength, endurance performance and impairs judgement. If you want to perform at your best, then you need to properly fuel.

If you keep getting injured or notice any of the other negative results above, you could be underfuelling. Females, if you’re not get your period, this is a very serious sign that you’re not eating enough and this should be immediately investigated further. It is not normal for female athletes to not get their period. Other signs of not eating enough include changes in mood such as irritability and depression.

If you’re an athlete, focus specifically on eating enough around exercise. Fuel up before you exercise and again afterwards. Don’t try to “save” calories for later on. Underfueling in the hopes of losing weight, doesn’t work; plus, our performance will be suboptimal and we may even end up injured and unable to exercise at all.

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Categories: Megan Kuikman

Megan Kuikman

Hello! I’m Megan Kuikman. I’m a Registered Dietitian with specialized training in sports nutrition. My goal is to help athletes and active individuals achieve a healthy attitude towards health, training, and food. I empower athletes to fuel properly for training in order to restore their health and enhance performance. You can get in touch with me at: hello@megankuikmanRD.ca


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