People often ask me “How much does an extra pound slow me down?” While studies show that carrying extra weight can make you slower, it’s not as straightforward as it seems.
A Classic Study
A well-known study by Kirk Cureton and his team at the University of Georgia in 1978 looked into this. Using a harness attached to their waist and shoulders, they added 5%, 10%, and 15% more weight to runners during a 12-minute running performance. They found that each extra pound added about 1.4 seconds per mile.
But It’s Not That Simple!
The results from this study might not apply to different paces, distances, sports (like swimming vs. biking vs. running), and weights. Plus, two people with the same weight can look and perform very differently. This is because body composition matters—muscle mass, fat mass, and water weight all play a role. Having more muscle and staying hydrated can make you heavier on the scale but will also boost your performance.
The Dangers of Under-Fueling
Another important factor for your racing weight is making sure you eat enough. Consistently being in a caloric deficit (burning more calories than you eat and drink) will hurt your performance and can cause serious health problems.
Relative Energy Deficiency in Sports (RED-S)
RED-S (prolonged and/or severe low energy availability) happens when there is a chronic mismatch between your nutritional intake and your energy expenditure. Not eating enough to support your body’s daily functions and exercise activities can cause many negative health problems, including:
- Decreased metabolic function
- Impaired reproductive function
- Poor musculoskeletal health
- Weakened immunity
- Reduced glycogen synthesis
- Compromised cardiovascular and hematological health
All these problems, individually and combined, lead to impaired well-being, increased injury risk, and decreased sports performance.
Potential Indicators of RED-S (including, but not limited to)
- For females: Secondary amenorrhea (absence of 3 to 11 menstrual cycles in a row) or oligomenorrhea (more than 35 days between periods for a maximum of 8 periods/year).
- For males: Sub-clinically low free or total testosterone, reduced sex drive, or decreased morning erections.
- Other signs:
- Repeated stress fractures
- Chronically low iron
- High total or LDL cholesterol
- Psychological symptoms: increased stress, anxiety, mood changes, body dissatisfaction, and/or body dysmorphia (intense focus, shame and anxiety over perceived body defects)
- Sleep problems
- Exercise dependence or addiction
- Extreme bradycardia, or low heart rate (HR) – HR<40 in adult athletes or HR<50 in athletes under 18 years old
- Low blood pressure (<90/60mmHg)
- Urinary incontinence in females
Focus on Health and Performance
Feeling the strongest and fastest that you can comes naturally through training and eating well. Focusing too much on weight loss can lead to disordered eating and an unhealthy relationship with food. Remember, the ultimate goals are better performance and overall health, not a specific number on the scale.
If you need help figuring out your energy needs for health and performance, dealing with RED-S, or how you can lose weight safely, fill out a short contact form here: https://questhealth.life/ask-about-nutrition-coaching/
