Reduced Caloric Intake Decreases Metabolism and Increases Injury Risk

Reduced Caloric Intake Decreases Metabolism and Increases Injury Risk

Do workouts feel harder lately? Do you feel like you are getting more injured than normal ?

Our clinic specializes in sports medicine, physiotherapy and Podiatry in downtown Toronto. It is our passion to ensure injuries are looked at from a dynamic lens, not just symptomatic treatment. 

I wanted to take the time to discuss the importance of fuelling for health, recovery, consistency and injury prevention. Runners are always told they need to run more and train harder to improve. We may not always emphasize the importance of meeting the required caloric intake to meet the demands we place on our body. As a runner, I am aware that less body mass can make it easier for your body to maintain a pace for a longer period of time. Prolonged calorie restriction, called Relative Energy Deficiency in Sport,  can lead to a multitude of health issues.

The medical term used to define caloric intake, is Energy Availability. It is calculated by taking energy intake (EI, measured in kcal) minus exercise energy expenditure (EEE, measured in kcal), divided by fat-free mass (FFM, measured in kg), or the amount of dietary energy remaining for normal physiological functioning after exercise (Loucks, 2007).Deficits in energy availability can lead to problems with hormones, bone health, reproductive health and metabolism.

Low EA . When a human is in a Low energy state, the body senses scarcity of fuel threatening survival, so it  sacrifices functions that are not immediately important to survival. Things that are sacrificed are growth and development. That could mean not recovering from a hard workout session and feeling tired in subsequent ones. As a Sports Medicine, Podiatry and Physiotherapy clinic In Downtown Toronto, we know training hard in a fatigued state can lead to injury. 

Low Caloric Intake Reduces Metabolism

People who are active should have a fast metabolism. That being said, if someone is restricting their calories, their metabolism actually is reduced. This was found in both male and female elite endurance athletes of lower total calorie intake. Studies have compared energy deficient athletes to non energy deficient athletes of equal energy expenditure, BMI and body composition, and found that those of the lower caloric intake had a lower metabolic rate.  RMR was 8% lower in the low EI (low EA) group, suggesting an energy conserving mechanism for maintenance of BMI and bodily function. 

Lower Testosterone Levels 

It is a known fact that reduced caloric intake impacts reproductive health. For women that means menstruation stops, men have less testosterone. That also means erectile dysfunction for men.

Estrogen and testosterone go hand in hand with bone health, that is because the endocrine system has a role in regulating bone health. Disruptions in bone regulation can lead to stress fractures, and long standing bone health implications, including an overall reduced bone density.

Being a team of sports medicine practitioners, physiotherapists and podiatrists, we always ask about calorie intake and diet to help indicate any suspicion of bone injuries in athletes.


Along with bone injuries, in a reduced caloric intake state, the body is not focused on repairing itself and recovering / getting the most out of the workouts. That means one may feel tired or fatigued and not able to bounce back from workout. When lingering fatigue meets pushing the body to its limits, it can break down, leading to injury. Most common injuries in runners are overuse injuries. Overuse injuries are already a risk factor for runners due to the repetitive motion running entail. Reduced energy intake greatly increases the overuse injury tipping point for runners. Some common running overuse injuries treated in our Downtown Toronto Podiatry, Physiotherapy and Sport Medicine Clinic include, plantar fasciiits, patellofemoral, achilles tendinopathy, stress fractures and iliotibial band syndrome. 

Signs and symptoms one may have too low of a caloric intake include:


  • fatigue
  • rapid weight loss
  • missed periods or delayed puberty (female athletes)
  • low libido (male athletes)
  • frequent illness
  • hair loss
  • trouble focusing
  • trouble staying warm
  • irritability


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