There seems to be a lot of discourse online about what exercise helps you lose the most fat. Many people will tell you that strength training is the best way because it elevates your metabolism because of EPOC and increases basal metabolic rate. Others will say that cardio, running specifically, doesn’t burn fat, it just burns calories. Then there are those who say cardio is not efficient because it takes hours of training to lose just a pound of fat. While all of these may be partially or completely true, they don’t tell the whole truth about running and fat loss.
How do you lose fat?
First we must address how fat is both stored and lost. It’s a mostly simple equation of calories-in versus calories-out. If you burn more calories than you ingest, you will lose weight; some of it being fat, some being water, and potentially some of it being muscle.
One pound of fat is the equivalent of about 3,500 calories, so if you want to lose a pound of fat per week, which is traditionally recommended, then you must be in a deficit of 3,500 calories per week, or 500 per day. Thus, if you consume more than you burn, you will gain fat.
Your body can store about 2,500 calories worth of carbohydrates in the form of glycogen. It’s stored in the skeletal muscles and liver, and is used for moderate to high-intensity exercise. After exercise, you must consume carbs to replenish your stores, but if you don’t, your body will perform gluconeogenesis, pulling from fat stores, protein, and lactate produced during exercise to rebuild glycogen. This is one of the precise ways in which a low-carb diet leads to fat loss.
“Running burns calories, not fat”
This is a common phrase used to diminish the benefits of running. Internet trainers use it to sell a plan that caters to the large percentage of people who “don’t like” doing cardio. The problem with this statement isn’t just that it’s misleading; it preys on people wanting the easy way out.
As I described above, calories are a unit of energy. Carbs and fat provide 4 and 9 calories per gram, respectively. These substrates can be replenished by consuming them, but stored carbs can also be restored by gluconeogenesis. So if you burn 500 calories during a run, you are now in a deficit, which is the first step in losing fat.
What makes this claim even weaker is the fact that running relies heavily on glycogen for energy production. Fat is a great source of energy, it provides roughly twice the calories per gram as carbohydrate, but it’s slow to metabolize and used primarily when sedentary or moving slowly. Running relies on a combination of fat and glycogen, and faster running shifts the balance more toward glycogen. When you deplete your glycogen stores, your body has to rebuild them, and gluconeogenesis is part of how that debt gets paid, using fat and other substrates in the process.
Lifting vs. running
I’m not here to argue that running is better than lifting. I think everyone should be doing both cardio and strength training on a regular basis. The idea that strength training is inherently better for fat loss just doesn’t hold up. You can burn far more calories per hour doing cardio, and the recovery is much lighter, making it more manageable to do on a regular basis. Strength training does burn more calories after the session through tissue repair (EPOC), but the recovery cost is steeper, often leaving you with a “weaker” training session for a day or two afterward.
Both are excellent for fitness and fat loss. If I want a client to lose fat quickly, I’ll typically have them do 60 minutes of light-to-moderate intensity cardio 4-5 days a week and perform 3-4 full-body strength sessions of 60 minutes each per week. This keeps the body in a constant state of repair and builds muscle, while low-to-moderate intensity cardio widens the calorie deficit.
So, Which is best?
Fat loss isn’t about picking the “best” exercise, it’s about maintaining a calorie deficit consistently enough that your body has no choice but to tap fat stores. Running does this efficiently: it burns a high volume of calories per session, depletes glycogen, and forces your body to replenish it, drawing on fat stores in the process. Strength training does it differently, building muscle that raises your resting metabolic rate over time. Neither is a shortcut, and neither works in isolation from what’s on your plate.
If you’re chasing fat loss, stop asking which exercise burns the most fat in a vacuum and start asking which combination you’ll actually do 4-5 days a week without breaking down. For most of my clients, that’s a mix of both cardio to drive the deficit, strength to protect and build muscle while it happens. The best exercise is the one that keeps you consistent long enough for the math to work.
About the Author
Josh Kober is co-owner and head coach at Glide Training Co., a personal training and run coaching studio in Bankers Hill, San Diego. He holds a degree in Exercise Science, an ACSM Personal Training Certification, and an RRCA Running Coach Certification, with 15 years of coaching experience helping clients build strength and improve running performance. Learn more at glidetc.com or visit the studio at 2056 1st Ave, San Diego, CA.