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Aerobic & Anaerobic Exercise for Weight Loss: How They Work

Sep 23, 2023
Aerobic & Anaerobic Exercise for Weight Loss: How They Work

Anaerobic and aerobic exercise for weight loss is essential as part of a comprehensive plan. The terms aerobic and anaerobic refer to how cells obtain energy. Aerobic processes require oxygen, whereas anaerobic processes do not.

Aerobic exercises are those that are sustained and keep the muscles supplied with an adequate and continuous supply of oxygen. Examples include jogging, brisk walking, biking, swimming, and rowing.

Anaerobic exercises do not require oxygen and are typically performed in short bursts of intense exercise. Examples include weight training and sprinting. Both types of exercise can assist you in reaching your weight-loss objectives.

How do aerobic and anaerobic systems work?

Adenosine triphosphate (ATP) is the energy currency used by every cell in your body. Because it is so essential to your body, it has multiple systems to produce and store it. When the terminal phosphate group is removed from ATP, energy is released and used by your cells.

Your cells can regenerate ATP from ADP, but they cannot produce a lot of ATP this way, as cells cannot safely store large amounts of ATP. Transferring energy from ATP to ADP can power your cells for about 4 to 6 seconds.

Creatine phosphate can transfer phosphate to ADP to produce creatine and ATP. Creatine allows muscle cells to store more readily available energy than ATP alone. Creatine phosphate provides about 15 seconds or so of energy, which provides energy during transitions.


Glycolysis (or breaking glucose, a 6-carbon sugar, in half) is an anaerobic process that does not directly require oxygen. Glycolysis takes place in the cytoplasm of cells. Glucose (a 6-carbon sugar) is split into two 3-carbon pyruvate molecules. Energy is released and stored as ATP or NADH, the reduced form of NAD. Pyruvate can enter the mitochondria if oxygen is available or be converted to lactate if not.1 If oxygen levels are low, lactate can be converted to pyruvic acid or glucose in the liver. This conversion costs 6 ATPs, so it is not energy efficient.

Net energy production from glycolysis is:  2 pyruvate molecules, 2 NADH, and 2 ATP.

Creatine phosphate and glycolysis provide more power than other forms of energy but do not have as much capacity to provide energy.

Aerobic metabolism

As long as oxygen is available, the pyruvate molecules are carried into the mitochondria and completely metabolized into carbon dioxide and water. This generates more ATP and high-energy electrons carried by NAD and FAD. Ultimately, most energy is generated when NADH and FADH2 shuttle electrons to molecular oxygen.

Net energy production: about 34 to 36 ATP

Two people high-fiving after running

What is aerobic endurance and anaerobic threshold?

Aerobic endurance is the length of time your muscles receive energy using aerobic pathways. Low-level, long-term exercise will stay below the aerobic threshold.

Aerobic capacity is an assessment of the capacity of the cardiorespiratory system to supply oxygen and the capacity of skeletal muscle to use oxygen.2. You can assess your peak oxygen capacity (VO2 max) using online calculators, a treadmill, or other exercise protocols.

Zone 2 exercise training is based on the premise that if you stay under the aerobic threshold, you can exercise longer and use fats preferentially over carbohydrates as a fuel source.  

The anaerobic threshold is when muscle metabolism converts to anaerobic processes. At peak levels of exercise, your mitochondria produce about one-third of the ATP you need. To make up for the difference, your muscles rely on anaerobic processes for energy. Waste products, increased potassium outside of cells, and increased muscle acidity cause muscles to fatigue more quickly.

What is the relationship between muscle fibers and metabolism?

Muscle fibers are divided into slow oxidative, fast oxidative, and fast glycolytic. This is based on their speed of contraction and their primary energy source. Oxidative fibers are rich in mitochondria and myoglobin. They rely on steady oxygen delivery, and they do not fatigue quickly. Slow oxidative fibers are prevalent in postural muscles.

Glycolytic fibers have large glycogen stores. They contract quickly and powerfully but fatigue more quickly than oxidative fibers.

Anaerobic and Aerobic Exercise for Weight Loss

Both aerobic and anaerobic exercise burn calories and, therefore, contribute to weight loss. The American College of Sports Medicine (ACSM) defines aerobic exercise as any activity that uses large muscle groups, can be maintained continuously, and is rhythmic in nature.3 Aerobic exercises burn calories at a lower rate, but the exercise can typically be sustained over a longer period. At lower intensities, your body uses a higher proportion of fat for energy. Aerobic exercise provides many cardiovascular health benefits.4  

Examples of aerobic exercises include:

  • Jogging
  • Brisk walking
  • Running
  • Cycling
  • Rowing
  • Swimming
  • Dancing

The goal of anaerobic exercise is to build muscle. These intense exercises are typically shorter in duration and fueled by energy sources inside the muscles. They burn fewer calories during exercise, but muscle continues to use calories even at rest. Resistance training also improves blood glucose control. It helps your body use insulin and glucose more efficiently. Overall, anaerobic exercise is preferred for weight loss because it is more time-efficient.5

Examples of anaerobic exercise include:

  • Sprinting
  • Weight-lifting
  • Plyometrics

Aerobic and anaerobic systems to supply your body with energy exist on a continuum. Both processes are used simultaneously, but as exercise intensity increases or decreases, one or the other predominates.

A scale, weights, apple and tape measure; aerobic and anaerobic exercise for weight loss

What if exercise and a healthy diet are not enough to induce weight loss?

Glucagon-like peptide 1 agonists (GLP-1 agonists) are proven medications that induce weight loss by slowing stomach emptying, regulating blood sugar, and reducing cravings and appetite. To qualify for a prescription for semaglutide, one of the most commonly used GLP-1 agonists, you must have a body mass index (BMI) of 30 or higher. You may also qualify if your BMI is 27 or higher and you have an obesity-related medical condition.

Semaglutide is used along with a nutritious diet and exercise. If you have questions about semaglutide, contact one of the Invigor Medical treatment specialists.

Get started today with a monthly subscription of Semaglutide.

Aerobic & Anaerobic Exercise for Weight Loss: How They Work
While we strive to always provide accurate, current, and safe advice in all of our articles and guides, it’s important to stress that they are no substitute for medical advice from a doctor or healthcare provider. You should always consult a practicing professional who can diagnose your specific case. The content we’ve included in this guide is merely meant to be informational and does not constitute medical advice.

Aerobic & Anaerobic Exercise for Weight Loss: How They Work

Leann Poston, M.D.

Dr. Leann Poston is a licensed physician in the state of Ohio who holds an M.B.A. and an M. Ed. She is a full-time medical communications writer and educator who writes and researches for Invigor Medical. Dr. Poston lives in the Midwest with her family. She enjoys traveling and hiking. She is an avid technology aficionado and loves trying new things.



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