Healthy Approach to Weight Loss for Runners

Deeper look into body weight and running performance, approaches to lose weight, and the suggested approach for Runners.
Healthy Approach to Weight Loss for Runners

Body weight is a very important factor that affects running performance. Body weight also influences the stress injuries that most runners face. When it comes to losing weight, the questions often runners have are what is the optimal body weight, and how to lose weight without affecting performance. This article deciphers the science behind body weight and suggests a healthy approach to weight loss.

Why do we need a lean body for Endurance Running?

In endurance running, a lean and light body helps us to move faster and longer because

  • Carrying a higher weight is more difficult than carrying a lighter weight on your body for long distances. Imagine carrying a 5-kilo weight on your back for a distance of 21 km or 42 km
  • Typically your joints take a load 4-5 times of your body weight. So, reducing your body weight is easier on your joints over longer distances.
  • Unlike a lighter body, in a larger body, the heart and blood vessels must work harder to send blood to the body parts.
  • In lighter bodies, the surface area to body weight ratio is high. Heat, inside the body, can dissipate faster, thereby cooling the athlete and helping him/her run longer and faster.
  • Higher levels of fat can prevent the dissipation of body heat. This can raise core temperature and thus slow down the athlete.

Human body weight is primarily the weight of muscles, bones, fat, and water. We do not recommend runners to lose muscle mass, bone mass, and water mass. In this article, when we say weight loss, we mean combined loss of fat, muscles, and even water. When we say fat loss, we are specific about the loss of fat mass.

Optimal Body Weight

There are various thoughts on optimal body weight for endurance runners. The following table is a good reference for the ideal range of body fat percentages for runners.

Fat as % of body weight
Age Men Women
20-29 3-9 12-19
30-39 5-11 13 -22
40-49 7-15 14-23
50+ 9-17 16-25

One might say that even bodybuilders are lean, but they are too heavy as they have higher muscle mass. So, to resolve that confusion, we can aim for a BMI (ratio of weight in kilograms and the height in metres squared) that is not lower than 19. So if you are 5 feet 7 inches tall and if you aim for a BMI of 19, then the lowest body weight would be 55 kilos.

What should be the appropriate rate of weight loss?

There are a variety of approaches that we see runners use to lose weight. Each of these approaches works differently, some bring down the weight quickly, while others work slowly. Also, while trying to lose weight with these approaches, people end up losing muscles, fat, and water. Sometimes, even bone mass is lost. Although people lose weight, they may not lose as much fat.

Here are the common approaches and how quickly they reduce the weight. We have deliberately used the term ‘weight loss’ here because people may think they are losing fat but they may not be losing fat. Rate of loss mentioned in the table below is the % of bodyweight lost per week.

Speed of loss Rate of loss Impact of loss Typical Approaches
Superfast ‘> 1.5% Most weight loss is water and muscle. Very little fat Detox diets, juicing, sauna, extreme calorie restriction, no water, low salt, diuretics etc
Fast 1% – 1.5% Mostly fat and lots of muscle loss Extreme intermittent fasting, high fibre low calorie diet, extreme high workout regimen
Moderate 0.5% – 1 % Mostly fat, moderate muscle loss Moderately low-calorie diet, high workout regimen
Slow ‘< 0.5% Mostly fat and little muscle loss Low calories, high nutrition diet. Moderate workout regimen

Is there a problem with losing fat fast?

We recommend that athletes focus on fat loss and not muscle loss. It is easy to be happy on the weighing scale where you might be getting weaker with muscle loss. Also, Fast and Super-fast weight loss can cause the body to bounce back with more fat again because the body gets into survival mode where

  • The body stops fat loss to survive (improve the body’s efficiency in energy utilization, reducing metabolism, and use other sources of energy). ex: prisoners of wars in history, crash dieting
  • The body increases fat storage for the future (improve fat storage efficiency and increase hunger). Ex: Hunger pangs after crash diet
  • The body reduces future fat loss by increasing fat cells. Ex: Folks putting on weight after great fat loss.

All of these can be seen in the ‘Biggest Loser’ contest in America, where most ‘Losers’ gained back and some more within 6 years.

We recommend a slow to moderate rate of fat loss to lose more fat, retain muscle and keep up the performance.

Is running a good way to lose fat?

The body uses fat to survive and maintain normal functioning, when at rest, when we do slow work, or when the body is in a calorie deficit mode. Calorie deficit happens when we expend more calories than what we consume [Calorie Output > Calorie Input].

Exercise is not a very efficient way to be in a calorie deficit. For example,

  • To create a 500 calorie deficit, one has to run anywhere between 7-10 kilometers. The same calorie deficit can be done by replacing the intake of 4 mugs of milk and sugary tea/coffee with 4 teacups of low-fat milk and sugar-free tea/coffee.
  • If we use only exercise and don’t control the food intake, we might end up eating more than the calories we burn through exercise. This is counterproductive.

Moreover, we can only exercise so much and exercise is not a punishment for the reward of food. Use exercises like running to improve the quality of your life with movement. Use food to manage your calorie deficit.

Then what is the role of exercise?

When we lose weight by dietary restrictions, we lose not just fat but also muscle, water, and other tissues in approximately the following percentages.

Weight Loss Component % of Weight Loss If you reduce 1 kilogram of weight, you lose
Fat 60% 600 grams of fat
Muscles 30% 300 grams of muscles
Water & other tissues 10% 100 grams of water

The above numbers can get very skewed if you are in a large calorie deficit.

Hypertrophy Exercises can reduce muscle loss to a large extent. However, it cannot build muscle in calorie deficit. So, it is better to use exercise to maintain as muscle mass as possible.

But many may say that runners don’t need muscles. This is not true because we will lose strength if we lose muscles, and we need strength to power our runs and speed us up. Additionally, strength exercises give an objective measure of success and improve motivation

What is the best approach for fat loss (not weight loss)?

Say you have dirty teeth. You brush your teeth for a day, and then stop brushing, will your teeth be fresh throughout your life?

Say you train and build strength to lift 100kilos deadlift. Then you stop training. Will your strength remain at 100kilos deadlift?

On a similar thought, we cannot stay lean just by losing rapid weight through a crash diet and then going back to our older ways. Train yourself to eat healthier so that you can lose and maintain weight loss for years to come. This training needs time and effort. It can be simple but not easy.

Every successful fat loss plan has 3 parts

  1. Restriction: to create calorie deficit via various methods such as excluding food groups, reducing portion sizes, counting calories, not eating for a certain time, etc.
  2. Planning your meals: Some protocols may have plans to manage obstacles and plans on adhering for the long term
  3. Adherence to the execution of the plan: If you fall off the wagon, then you lose the benefits of the fat loss plan.

Optimal nutrition for a healthy fat loss also maintains your muscle mass and other metabolic health. Such nutrition will have

  • Optimal macros –
    • High on proteins, (30% of total calories)
    • Moderate on carbs (40% of total calories), and
    • Moderate on fats ((30% of total calories).
  • Loads of veggies for vitamins, fibres, and phytochemicals such as flavonoids, carotenoids, and phenolic acids
  • Relishable taste for satisfying one’s heart and soul

What are the steps for fat loss?

  1. Get to know your BMR based on your weight, age, and lifestyle. e.g., BMR = 2500 calories
  2. Using the BMR, figure out your calorie needs to maintain weight. e.g., BMR = Maintenance calories. Say 2500 calories
  3. For a slow to moderate fat loss, reduce 200-500 calories from your maintenance calories. Net calorie in take = 2500 - 500= 2000
  4. Divide the calories into portions for proteins, carbs, and fats. e.g., 800 calories for carbs, 600 for proteins, 600 for fats.
  5. Plan your meal so that you have total calories apportioned across these macros.
  6. Fine-tune the calories and the macros based on feedback from your weight scale.

Scale down the calories if the weight is increasing or not lost, scale up the calories if the weight is lost too fast, and maintain the calories if the weight loss is happening at a good pace.

Is there anything that can be done to increase the ‘Fat Metabolism’?

There are various ways to increase your ‘Fat Metabolism’ (or using Fat as the primary fuel)

  • Maintain or increase your muscle mass. Muscles burn more calories and hence maintain or increase your BMR.
  • Walk, jog, and slow/easy running tap into fats as fuel.
  • Sleep 7-8 hours a day. Lack of good sleep indirectly messes up fat metabolism.
  • Keep good metabolic health i.e., blood lipid profile, insulin sensitivity, vitamin profile.
  • Reduce stress as stress can indirectly reduce fat metabolism.

Many people may use fasted cardio to increase ‘Fat Metabolism’. It is agreed that fasted cardio or running can tap into fat as fuel if the person is doing the cardio slowly. However, the body compensates by storing fat during the rest of the day. Runners can train their bodies to use fat as fuel by doing fasted cardio. However, the jury is still out, if fasted cardio can burn more fat than fed cardio. Similarly, HIIT protocol may also not increase ‘fat metabolism’.


  • Runners can benefit from lower body weight with lesser fat
  • Slow to moderate fat loss is better than faster fat loss
  • Eat healthy and reduce your calorie intake to lose fat
  • Strength train during fat loss to maintain muscle mass
  • Maintain good sleep hygiene and reduce stress to increase fat loss


Sujoyjeet is a certified nutritionist and a personal trainer. To provide actionable insights to clients, he understands his clients lifestyle before providing a habit-based nutrition plan. The habit based nutrition plan teaches his clients how , what & when to eat and why to eat certain specific foods to meet their health, performance and body composition goals. He can be reached at @myinsight_nutrition.

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