why lifting and crossfit are so great for improving body composition and long term metabolic health
TL;DR
EPOC (“afterburn”) is the extra energy your body uses after training to repair muscle, restore oxygen, and rebalance hormones
CrossFit and heavy resistance training create the largest EPOC response and the biggest improvements in insulin sensitivity*
Steady state cardio supports heart health but has a smaller afterburn and less impact on muscle repair
Higher EPOC = better metabolic flexibility and fewer consequences from the occasional indulgences we all love, think mimosas or croissants
Exercise isn’t just about what happens during the workout. Many of the most important metabolic benefits occur after you’re done, when your body is repairing muscle and replenishing energy. This recovery phase is where insulin sensitivity improves and EPOC comes into play.
*Insulin sensitivity determines how efficiently your body deals with carbohydrate intake. When you’re insulin sensitive, glucose is quickly shuttled into muscle to be used or stored supporting energy, recovery, and stable blood sugar. When insulin sensitivity is poor, more insulin is required to manage the same amount of glucose. Over time, this leads to fat gain, energy crashes, and increased inflammation
What Is EPOC and Why You Want More of It
EPOC (Excess Post-Exercise Oxygen Consumption) refers to the elevated oxygen and energy your body uses after intense exercise to return to baseline.
During this window, your body is repairing muscle tissue, replenishing ATP and glycogen, and regulating hormones and body temperature
All of this requires energy, meaning your metabolism stays elevated for hours - and sometimes up to a full day after certain workouts. The greater the intensity and complexity of the exercise, the larger the EPOC effect.
Heavy Resistance Training & Barbell Lifting
Heavy resistance training is one of the best ways to improve insulin sensitivity. Muscle contractions increase glucose uptake during and after training, and increased lean muscle mass improves your ability to manage blood sugar. The mechanical stress of heavy lifting creates a strong muscle repair signal, which keeps energy demands elevated well after the workout.
EPOC: Moderate to high, especially with heavy compound lifts and shorter rest periods.
CrossFit & High-Intensity Functional Training
CrossFit blends heavy lifting with high-intensity conditioning, making it particularly powerful for metabolic health. Rapid glycogen depletion and full-body muscle recruitment dramatically improve post-workout glucose uptake. At the same time, the combination of mechanical and metabolic stress increases recovery demands across muscle, connective tissue, and the nervous system.
EPOC: High—often among the largest of any training style, with elevated metabolism lasting 12–24 hours.
Long Steady-State Cardio
Examples: Jogging, cycling, rowing at a consistent pace
Steady-state cardio improves insulin sensitivity primarily during and shortly after activity by enhancing mitochondrial efficiency and glucose use. However, these effects are often short-lived unless training volume is high. Muscle repair demands are relatively low, and EPOC is minimal—most energy is burned during the workout itself.
EPOC: Low
Why This Matters for Real Life, Including Food
Higher EPOC doesn’t mean you can eat without limits—but it does widen the margin for error.
When your body is in a prolonged recovery state, it is:
Actively refilling muscle glycogen
Shuttling glucose into muscle instead of fat
Burning more energy at rest
In practical terms, this means people who lift heavy or train intensely often tolerate carbohydrates and indulgences far better than those relying on cardio alone. It’s the difference between a mimosa and croissant being a metabolic setback or something your body can handle better.
Strong muscles + high recovery demand = metabolic flexibility.
The Bottom Line
If your goals include insulin sensitivity, body composition, and long-term metabolic health, resistance training should be the foundation. CrossFit and high-intensity functional training amplify these benefits through larger EPOC and greater muscle repair demands, while steady-state cardio plays a supportive role.