Lighter Isn’t Always Faster: What Every Athlete Needs to Know About Running Performance

Have you ever heard (or thought):

“If I just lost a few pounds, I’d be faster.”

“I need to lean out for race season.”

“Lighter equals faster, right?”

You’re not alone — but this belief could be the very thing holding you back from running your best.

In the running world, it's common to hear that a lower body weight equals better race results. But when you dig into what truly drives running performance, the picture is much more complex. And often, runners who focus on weight loss end up sabotaging the very thing they’re trying to improve: how well they run.

Let’s bust the myth and talk about what actually improves running performance — and what might be holding you back.

Why Weight Loss Doesn’t Guarantee Better Running Performance

It’s easy to look at elite runners and assume low body weight is the key. But here’s what most people miss: elite athletes don’t perform well because they’re lean — they perform well because they’re highly trained and often genetically gifted.

In fact, genetics play a huge role in both running ability and body composition. Some elite runners may be well-fuelled and recovered, while others may not be — and yet they still perform at a high level because of their unique genetic makeup.

Leanness might be a byproduct of their genetics or training (and possibly their nutrition) — not the reason they’re fast.

When recreational runners try to lose weight to improve speed, the outcome is often the opposite of what they expect.

Instead of feeling faster, they feel:

• Sluggish on runs

• Sore for days

• Hungrier and more fatigued

• Emotionally burnt out

• Stuck in a cycle of injuries or plateaued progress

Why? Because the pursuit of weight loss usually leads to underfuelling.

Underfuelling: The Hidden Enemy of Performance

If you are intentionally (or unintentionally) eating less than what your body needs to support both training and basic human functions you can slip into a state of Low Energy Availability (LEA), or in more chronic cases, Relative Energy Deficiency in Sport (RED-S) — similar to your phone going into low power mode. In order to conserve energy it starts dow regulating systems, such as the reproductive system, thermoregulation system, cardiovascular system, immune system and the digestive system.

Unfortunately, underfuelling has become the norm in a variety of sports because we live in a society that praises leaner bodies. But you can’t expect your body to perform well if it’s constantly running on empty. Underfuelling or low energy availability can lead to:

• Plateauing times despite harder training

• Increased fatigue, tiredness, or sluggishness

• Lost or irregular menstrual cycle

• Frequent injuries (e.g. stress fractures)

• Digestive issues (e.g. constipation and bloating)

• Low mood and sex drive

• A frustrating relationship with food and body image

If any of these sound familiar to you, it might be time to consider reaching out to your physician and/or registered dietitian who specializes in sport for support.

What Actually Improves Running Performance

Performance isn't about what your body weighs, it’s about how well you've fuelled and recovered. Runners have bodies of all shapes and sizes.

If you truly want to run stronger, longer, and faster, your body needs:

• Carbohydrates to fuel long runs, speed work, and recovery

• Adequate calories to support daily energy needs and repair

• Protein to preserve/build lean muscle mass

• Staying hydrated with fluids & electrolytes

• Fuelling before and after every run to support performance and adaptation

• 7-9 hours of sleep for adequate recovery

• Strength training to help prevent injury

• Rest days

Stop Letting the Scale Define Your Success

If stepping on the scale is dictating your training confidence, it's time to rethink the goal. Your weight does not determine your worth as a runner or define your performance. If your pursuit of “lighter” is costing you strength, energy, or joy in running, is it really worth it?

The fastest runners aren’t the leanest — they’re the most consistent, most recovered, and best fuelled.

If you stopped focusing on the scale, what would it look and feel like for you to chase performance instead? Because you deserve to feel strong and perform well.

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Ready to Improve Your Running Performance?

I help runners fuel for real-life performance — without restriction, confusion, or burnout. Whether you're training for a 5K, half marathon, or full, you don’t need to weigh less to run faster. You need a strategy that supports your training, energy, and recovery.

Ready to fuel smarter and run stronger — without the pressure of chasing a lower weight? Book a discovery call today and let’s build your personalized performance plan.