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Running and Weight Loss: How to Safely Lose Weight Without Sacrificing Your Training

Body weight and composition are common concerns among runners at all levels. Some runners are new to the sport and incorporate running as a healthy way to promote weight loss. Some runners have been in the sport for a while and are curious if weight loss will help improve performance.

Whatever the case, weight loss and running can go hand-in-hand, but it takes careful planning and a realistic understanding of the body and weight loss works. In this article, we’ll look how to assess your body composition to determine if weight loss is an appropriate goal and then specific strategies to help you safely and effectively lose the weight without derailing your training.

Weight loss and body fat

Common goals for weight loss in runners include losing body fat and increasing lean body mass.

Indeed, excess body fat can inhibit performance. Unlike muscle, fat is non-force-producing mass meaning that it is there, but doesn’t help propel the body into motion. Excess body fat has also been associated with reduced aerobic capacity and endurance.

However, keep in mind that muscle and fat are not interchangeable. To change body composition you must simultaneously lose body fat by maintaining a caloric deficit and increase lean body mass through exercise and strength training.

Having a body composition that is lower in fat mass does not necessarily mean lower body weight. It is important to view weight loss in terms of body composition goals vs. body weight goals because too low of a body weight can be detrimental to athletic performance and overall health. Also, body composition is a better marker of health and fitness than weight alone. The appropriate percentage of body fat is individualistic for each athlete and it should be recognized that athletes of many shapes and sizes can enjoy the same health and athletic success.

Normal healthy body fat percentage

The following chart shows a range of healthy body fat percentages for general health and for individuals who participate in regular physical training:

Body Fat %
Age Women Men
General health <55 20-35% 8-22%
>55 25-38% 10-25%
Physically active <55 16-28% 5-15%
>55 20-33% 7-28%


At the bottom of this article, we’ve included a list of ways to measure and test your body fat percentage.
While a lower percent of body fat has advantages for runners, it is possible to have too little body fat. A body fat below 5% for men and below 12% for women can result in health problems and impaired athletic performance.

How to approach losing weight while maintaining running performance and overall health

If weight loss is appropriate for you, here is a step-by-step process for losing weight while staying healthy and maintaining energy levels to support your training.

1. Start by estimating what your daily caloric intake should be, which can be done by using a prediction equation for resting metabolic rate (RMR). One such equation (the Mifflin equation) is below:

Males: 5 + (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years)

Females: -161 + (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years)

2. Next you would multiply this number by an activity factor decided by your daily activities. These activity factors can range from 1.2-1.4 for sedentary activities, up to 1.9 to 2.5 for those who work long shifts doing demanding jobs.

3. Finally you would add in the number of calories you are estimated to burn through training.

If you hate math or you just want a quick and easy way to estimate your daily calorie expenditure, try our free calorie calculator for runners.

Cutting calories to promote weight loss

Once you know about how many calories you need to support your daily living and exercise, you want to decide how many calories you can cut out to promote weight loss.

There are roughly 3500 calories in one pound of fat. So if you wanted to lose 1 pound per week (7 days), you would need to cut out 500 calories per day. Here are some reasonable weight loss goals:

  • If you weigh less than 150 lbs, you could aim to lose 0.5 to 1 pound per week (250 to 500 calories less per day)
  • If your starting weight is higher, you could aim to lose 1 to 2 pounds per week (500 to 1000 less calories per day)

You diet should never be providing you less than 1200 calories per day. Below that point it will be too difficult to get enough vitamins and nutrients to support health and performance. Also, when you cut back calories too much you are more apt to get too hungry and will end up blowing you “diet”.

Very low calorie diets may also promote muscle loss and result in a slow metabolism, making weight loss more difficult.

Tips for losing weight in a healthy way

The following are some useful tips on how to lose weight healthfully and keep weight loss a manageable part of your training plan.

  • Find a way to make your favorite foods a part of your diet instead of denying yourself those foods. Give yourself a favorite treat once or twice a week.
  • Try eating smaller meals every 3-4 hours and eat mindfully. Try not to multi-task while eating and take time to enjoy your food. Also keep in mind that your brain needs about 20 minutes to get the signal that you are full.
  • Add in more fruits, vegetables, and whole grains. These foods promote satiety and keep you fuller longer.
  • If eating too much at night is an issue for you, try frontloading your calories by having a bigger breakfast and lunch and a smaller dinner.
  • Think positive thoughts. Dieting and training for endurance events are both hard and some days will be better than others. Give yourself a mental edge by visualizing a leaner, fitter you each day.

Before beginning a weight loss program it is a good idea to have a health screening from your doctor to identify any medical conditions that may need to be addressed.

Also, be realistic about your weight loss goals. Each individual has a “set-point” for weight that his or her body performs best at. If you don’t have any body fat to lose, your body will try to conserve energy and you will find it difficult to lose weight.

Finally, weight loss and changes to body composition should be undertaken in the off-season or early on in the competitive year before hard training and competitions begin.

If you are interested in making weight loss part of your training plan, you can check out the nutrition counseling we offer through the website that can start you on your way to becoming a fitter, faster runner.


Clark, N. Nancy Clark’s sports nutrition guidebook. 3rded. 2003.Dunford, M. Sports nutrition: a practice manual for professionals. 4thed. American Dietetic Association; 2006.Frankenfield, DC. Validation of several established equations for resting metabolic rate in obese and nonobese people. J Am Diet Assoc. 2003;102;1152-1159.

Heyward VH, Wagner DR. Applied Body Composition Assessment. Champaign, Ill: Human Kinetics; 2004.

How to measure body fat

These are listed from most accurate (and generally most costly), to least accurate:

1) DEXA scan- a type of full-body x-ray that can distinguish fat from muscle and bone. It is considered the “gold standard” for accuracy in measuring body fat. DEXA scans can also determine bone mineral density, which also can be useful for runners. However, the scans can be very expensive and it is difficult to find a facility with the machine.

2) Bod Pod- the pod measures the volume of air you displace which allows it to measure your density. The assumed density of fat, muscle and bone are used along with calculated body density to determine percentage of body fat. Again, facilities with these machines can be difficult to find.

3) Underwater weighing- body density is determined by dividing body weight measured on land by body volume measured by water displacement when submerged in water. The assumed density of fat, muscle and bone are used along with calculated body density to determine percentage of body fat.

4) Skinfold calipers- based on the assumption that subcutaneous fat represents a certain proportion of total body fat. Skinfold measurements are taken at 3-6 common sights on the body and body fat percentage is derived using the sum of these measurements and skinfold equations. The accuracy of this method depends a lot on the equipment used and the person taking the measurements.

5) Bioelectrical impedance- a small alternating current is passed through the body. Tissues with large amounts of fluids and electrolytes, such as blood, allow the current to pass freely whereas as tissues like fat, bone, and lungs have high resistance. The impedance measured is used in derived equations to give an estimate of fat-free mass, from which body fat can be calculated. This method is easy, convenient, and low-cost. However it is not as accurate, especially in select populations, compared to the other methods.

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  • How to calculate your exact glycogen storage and carbohydrate use so you know exactly how much you have to refuel
  • How to calculate your sweat loss and re-hydration rate to maintain optimal performance.
  • How to develop your individualized fueling plan using you sweat rate and glycogen usage.
  • How to practice during training and fuel up for race day.
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One Response on “Running and Weight Loss: How to Safely Lose Weight Without Sacrificing Your Training

  1. When I was running a lot and training for things, I could NOT lose weight! I know now that it was because I was a cardio junkie and I wasn’t doing the necessary strength training my body needed. It’s funny, I had to stop running for 2 months because of an IT Band issue and I started lifting weights…I lost 5 pounds immediately!

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