A Sports RD Weighs in on Weight and Performance


Whether you’re working out to lose weight or losing weight to perform better, being thin and lean is important in many sports. In the fitness world, looking the part can provide a sense of belonging. More important, putting effort into exercise should help focus on a healthy lifestyle, which for some includes obtaining or maintaining a healthy weight.

However, when it comes to having the best performance, seeing a lower number on the scale isn’t always the best approach. Here’s a look at when to lose and when you might want to maintain or even gain weight to ramp up your results:


We hate to think of losing weight as being something that contributes to an athlete taking the top spot on a podium, but the fact is, simply being lighter can help improve performance. Activities that demand high amounts of agility, flexibility, quickness, speed or those that rely on carrying bodyweight against resistance like gravity are the ones that benefit from being lighter. To name a few, these sports include endurance running, cycling uphill, jockeying, high jump, pole vault and dance.

For these sports, losing weight equates to improving efficiency by reducing energy costs of performing the same task at a lower weight than a higher one. It is estimated that losing 10 pounds alone can shave 20 seconds off each mile of running. Reducing excess weight not only adds speed but takes away from the impact of running, creating less pressure and stress on the joints which allows the athlete to go harder for longer day after day. For cycling, losing weight while performing the same amount of power output strengthens the power-to-weight calculation, essentially creating ‘free speed.’


There are many sports that demand an athlete have a large body mass to perform well. Football players are a key example of needing to be large in stature to hold their own on the field. Other sports that benefit from a larger body size and typically see athletes with larger body masses and body fat percentages are basketball and volleyball. Swimming is another example of when being very lean can work against performance results as a little extra body fat can help create buoyancy.

Beyond a sport’s unique demand on bodyweight, a key factor is how well the individual athlete can promote a healthy body composition to capitalize on performance gains. Losing too much too quickly can be a risky endeavor, setting the athlete up for long-term problems with recovery, energy and general health. Consuming less than needed to provide usable energy might lower weight but comes with lower power outputs, less strength and reduced endurance — exactly the opposite of optimal performance. Weight gain in the form of muscle can be very beneficial to provide the athlete with more a efficient and performance-oriented body composition. Sprinters, weight lifters, long jumpers and gymnasts can all promote higher intense power outputs by increasing muscle mass. This increases an athlete’s overall weight, but creates a more desirable body composition (increased fat-free mass) to meet performance markers.


In the end, there’s more to weight than performance. To determine if you need to lose or gain weight, first consider these factors: current health status, current weight, current BMI, current fitness level, preexisting health conditions, body fat percentage and both short- and long-term goals.

Once you have all that dialed in, look at how weight helps meet the unique performance demands of your sport and individual goals. If your performance could benefit from a leaner, lighter body, start watching portion sizes, load up on produce, cut out excess (sugar, alcohol, processed foods, sauces) and keep your loss to roughly one pound a week.

If gaining weight will be a more strategic move, bulk up on calorie-dense whole foods (nut butters, coconut, trail mix, avocados, smoothies), consume frequent meals and aim to gain roughly one pound a week. Whether you’re looking to lose or gain, remember weight is more than a number on the scale; while weight itself is a great health marker, to help performance, it is also important to either lose body fat or gain muscle. To make those gains (or losses) stick, go about it in a slow, healthful way and consult a sports dietitian to help you reach your individual target.


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