VO2 Max and Weight Loss: Losing Weight Increases VO2 Max?
Reading time: 6 min

VO2 Max And Weight Loss: Losing Weight Increases VO2 Max?

Reading time: 6 min
Learn how losing weight affects VO2 max.
VO2 Max and Weight Loss: Losing Weight Increases VO2 Max?

For endurance athletes, achieving a high VO2 max and maintaining low body fat are crucial for boosting performance and enabling longer, faster efforts with greater efficiency. 

In this blog, we look at the connection between the two and explain whether weight loss truly increases VO2 max. 

Understanding VO2 max

VO2 max is your maximum aerobic capacity. It is the maximum amount of oxygen your body can use during intense exercise, serving as a key indicator of cardiovascular fitness and aerobic endurance. It reflects your body's ability to efficiently use oxygen, important for performance in endurance sports.

Relative and absolute VO2 max

Relative VO2 max is the amount of oxygen you can use during exercise relative to your body weight, usually measured in milliliters per kilogram per minute (ml/kg/min), allowing comparison across individuals of different sizes.

Absolute VO2 max measures the total volume of oxygen used without weight consideration, expressed in liters per minute (L/min), providing a measure of overall oxygen use.

Meaning, weight loss, especially if it involves losing fat mass, can increase relative VO2 max because it's calculated per unit of body weight. However, absolute VO2 max might not change significantly unless the weight loss is accompanied by cardiovascular or muscular improvements.

Increase your VO2 max with our FREE 10-Week Training Plan.

Finnish researchers suggest that for accurately assessing VO2 max, it's better to use lean mass rather than total body weight, as lean tissue is what consumes oxygen. Their study showed a clear relationship between lean mass and VO2 max, unlike when using total weight or height.

The researchers did further analysis to show that relative VO2 max is actually inversely proportional to fat mass – that is, the more body fat you have, the lower your relative VO2 max.

In fact, fat mass is a better predictor of relative VO2 max than exercise performance (how far/fast you go in the VO2 max test).

Do you use smartwatches like Garmin and Apple to track your VO2 max? Read how accurate they are!

Fat burning zone and Fatmax

Endurance athletes often seek ways to burn more body fat and enhance their performance. The body's ability to burn fuel, carbohydrates and fat, is crucial for performance.

Aerobic training makes the body more efficient at burning fat, which is why elite marathon runners can sustain long runs without "hitting the wall".

Researchers from Birmingham University studied the optimal exercise intensities for fat metabolism in male endurance cyclists. They introduced two key metrics: Fatmax (intensity at which fat oxidation is highest) and Fatmax zone (range of intensities where fat oxidation rates are close to Fatmax).

The study found that fat oxidation peaks at an average intensity of 64% VO2 max, but this varies widely among individuals.

The concept of the "fat-burning zone" (FBZ) suggests that exercising at lower intensities (around 50-65% of VO2 max) maximizes fat burn. However, while FBZ workouts might burn a higher percentage of calories from fat, they often burn fewer total calories than higher-intensity workouts.

This means that the total fat calories burned might be the same or even less than in a more intense session. Moreover, focusing solely on FBZ workouts can be counterproductive, as higher-intensity exercises can create an energy deficit, leading the body to tap into its fat reserves.

Key points for fat burning:

  1. Train aerobically at the higher end of your Fatzone (around 60-80% of max heart rate) for maximum fat burning.
  2. Increase total weekly training volume. Longer sessions are preferable for fat burning than short ones.
  3. Training longer after your last meal increases energy derived from fat.
  4. Avoid carbohydrate drinks before or during exercise, as they suppress fat burning.

The best strategy varies depending on the season and the athlete's goals. In the early season, the focus is usually on building endurance and optimizing body composition, often meaning shedding excess body fat.

Training protocols that build endurance are also beneficial for fat loss. However, optimizing fat burning is different from optimizing performance.

Practical advice for early-season training:

  1. Limit pre-exercise carbohydrate intake.
  2. Choose low GI (=glycemic index) pre-exercise meals and snacks.
  3. Train in temperatures of about 10-20C.
  4. Consider supplements like green tea extract and black tea.
  5. In the later season, the focus shifts to maximum performance. Carbohydrates become more crucial as they are the primary fuel for high-intensity exercise.

Practical advice for later-season training:

  1. Designate specific workouts as "fat burning".
  2. Use green tea extract and ensure post-training recovery with a carbohydrate-protein drink.
  3. Use carbohydrates normally for other workouts.
  4. Consider supplements like caffeine and zero-carb electrolyte drinks.
  5. Lastly, athletes should always listen to their bodies and adjust their strategies accordingly. The day-to-day diet remains crucial, especially after carbohydrate-free training sessions.

It is important to keep in mind that fat burning is different in each athlete and changes with training.

Best supplements to boost VO2 max and fat loss

High-quality supplements can significantly enhance athletic performance by providing the body with essential nutrients that support energy production, recovery and overall health.

Supplements aimed at increasing VO2 max can improve oxygen utilization during trainings, leading to better endurance and performance. Additionally, certain supplements can aid in fat burning by boosting metabolism and enhancing the body’s ability to use fat as an energy source during trainings.

Let’s take a look at the best supplements to reach your goal.


Adaptogens, such as ashwagandha, rhodiola, and cordyceps, are known to enhance oxygen flow in the body, directly impacting VO2 max levels. By improving the efficiency of oxygen transport to the muscles, these natural compounds support better endurance and performance.

This increased oxygen availability allows athletes to sustain higher levels of physical activity for longer periods, contributing to improved VO2 max, which is a critical measure of cardiovascular fitness and aerobic endurance.

Discover the top 5 adaptogens to boost performance.

A higher VO2 max improves the body's ability to utilize oxygen more efficiently during exercise, leading to increased fat burn. This enhanced aerobic capacity allows for more intense and longer-duration workouts, contributing significantly to fat loss efforts.

You can purchase products with a high concentration of a specific adaptogen or a blend of several, such as Absolute, Adaptogen Fuse, and Loaded.

60 capsules
Adaptogen FuseAdaptogen Fuse
4Endurance Pro

Complete adaptogen mix

Sale price€29,99
17 reviews
84 capsules
4Endurance Pro

VO2 max booster

Regular price€59,99 Sale price€30,00
- 50%
39 reviews
90 capsules
4Endurance Pro

Fat burn, VO2 max

Regular price€39,99 Sale price€29,99
- 25%
35 reviews
60 capsules
Rhodiola ComplexRhodiola Complex
Rhodiola Complex
4Endurance Pro

3% rosavins, 4% salidrosides

Sale priceFrom €19,99
No reviews

But if you’re looking for an “all in one” type of product, we recommend Fusion.

A powerful fat burner designed specifically to boost your metabolism and increase energy levels during training, while also boosting VO2 max.

Its main ingredients are green tea extract, rhodiola, ginger extract, and cayenne pepper extract. All active ingredients allow you to burn fat in three ways:

  1. Boost metabolism to increase your body’s ability to burn fat.
  2. Increase energy levels which allows you to train harder and burn more fat.
  3. Increase oxygen flow (VO2 max) to further improve your training efficiency.
Use Fusion before exercise to stimulate your body's ability to use fat as energy and reduce stress levels.


L-Carnitine plays a vital role in fat metabolism by transforming triglycerides into energy, especially beneficial during low-intensity workouts, while also reducing muscle lactic acid.

This not only aids in fat loss by enhancing the body's ability to burn fat for energy but also supports sustained energy levels.

Its deficiency, often seen in vegetarians, vegans, or those with specific genetic conditions, highlights its importance in optimizing cellular energy functions, making it an essential supplement for those looking to improve athletic performance and achieve weight loss goals. Learn more about how L-carnitine affects fat burn.

You can choose among various products with L-carnitine, such as L-carnitine tartrate, Thermo Burn, and Acetyl-L-Carnitine.

90 capsules
4Endurance Pro

Fat burn, VO2 max

Regular price€39,99 Sale price€29,99
- 25%
35 reviews
90 capsules
L-Carnitine TartrateL-Carnitine Tartrate

Convert fat into energy

Regular price€17,99 Sale price€14,99
- 17%
No reviews
84 capsules
4Endurance Pro

Remove excess water

Regular price€39,99 Sale price€29,99
- 25%
No reviews
90 capsules
Thermo BurnThermo Burn

Thermogenic & appetite suppressor

Regular price€14,99 Sale price€9,99
- 33%
No reviews

Since all endurance athletes need a good energy gel by their side, we recommend Energy Gel with L-Carnitine.

  1. It improves fat oxidation.
  2. Boosts your metabolism.
  3. Increases focus and motivation.
  4. Enhances performance which allows you to train more.

Another reason we believe it’s the best choice is that it pairs with Fusion very well. These two work in tandem and improve your performance by giving you high levels of energy and boosting fat metabolism.

Use Energy Gel with L-Carnitine during exercise to provide your body with reliable source of carbohydrates.

We have a whole blog dedicated to this duo. If you want to optimize your trainings by having more energy and less fat, learn how.


Losing weight effectively raises relative VO2 max by reducing body weight, which in turn increases the oxygen volume available per kilogram of body weight. However, without simultaneous improvements in cardiovascular or muscular systems, absolute VO2 max, the total oxygen consumption, may not see significant change.

Understanding the Fat-burning Zone (FBZ) and FatMax zone is vital for weight loss because they identify the most efficient intensities for burning fat. These concepts guide athletes to train at levels where fat oxidation is maximized, helping to optimize energy use and enhance weight management strategies.

Adaptogens such as ashwagandha, cordyceps, and rhodiola rosea enhance energy, allowing for more intense training and a higher VO2 max, facilitating easier access to the FatMax zone for optimal fat burning. Meanwhile, L-carnitine supplements accelerate metabolism and fat oxidation, complementing this process efficiently.