Clinically reviewed by Associate Professor Christopher O’Donnell, Nurse Practitioner, FACN · Founder and Clinical Director · AHPRA NMW0001453715 · Last reviewed
Muscle is metabolically active tissue that burns energy at rest, acts as the body’s largest site of glucose disposal, and protects function with age. Preserving it during weight loss keeps energy expenditure higher, which is a central reason resistance training belongs in any weight management plan.
What muscle does beyond movement
Skeletal muscle is the largest organ system in most people and does considerably more than move you around.
It is the primary site of glucose disposal after meals, taking up the majority of glucose from the bloodstream. It stores glycogen, acts as a protein reserve during illness, and produces signalling molecules called myokines during contraction, which have effects on inflammation and metabolism throughout the body.
Setting a realistic expectation on calories
A claim circulates that each kilogram of muscle burns fifty or more calories per day at rest. That figure is not accurate. Resting muscle uses roughly thirteen calories per kilogram daily, compared with about four to five for fat tissue.
So gaining two kilograms of muscle adds perhaps twenty six calories per day at rest, which is modest. The real value of muscle is not its resting burn. It is glucose disposal capacity, energy used during and after training, preserved function, and the prevention of the metabolic slowdown that comes with losing it.
What happens without resistance training
During weight loss without resistance training, a meaningful proportion of what you lose is lean tissue rather than fat. Estimates commonly range from twenty to thirty percent of total loss.
This has a compounding effect. Less muscle means lower energy expenditure, which means the deficit shrinks, which means loss slows and maintenance becomes harder. Repeated cycles of loss and regain without resistance training can leave someone at a similar weight with a worse body composition than when they started.
What adequate training looks like
The requirement is more modest than most people assume.
- Two sessions weekly is sufficient to preserve muscle during weight loss, and is the usual guideline minimum
- Cover the major movement patterns: a push, a pull, a squat or hinge, and something for the core
- Progressive overload matters. Gradually increasing load, repetitions or difficulty is what drives adaptation
- Bodyweight, resistance bands, free weights and machines all work. Consistency matters more than equipment
- Pair it with adequate protein, since training without sufficient protein limits the benefit
Why this matters more with age
Adults lose three to eight percent of muscle mass per decade after 30, accelerating after 60 and after menopause in women. This age related loss, sarcopenia, is a major driver of frailty, falls and loss of independence.
Resistance training is the most effective intervention against it, and it works at every age including into the eighties and beyond. A weight management plan that ignores muscle is solving one problem while creating another. Speak with our team.
Frequently asked questions
How many calories does muscle burn at rest?
Around thirteen calories per kilogram daily, compared with four to five for fat tissue. The popular claim of fifty or more per kilogram is not accurate.
How much resistance training do I need?
Two sessions weekly covering the major movement patterns is sufficient to preserve muscle during weight loss and meets guideline minimums.
How much muscle do you lose when dieting?
Without resistance training, commonly twenty to thirty percent of total weight lost comes from lean tissue. Training and adequate protein substantially reduce this.
Is cardio or weights better for weight loss?
Both have value, but resistance training is more important for preserving muscle and protecting energy expenditure, which matters most for maintaining loss.
Can you build muscle while losing weight?
It is possible, particularly for people new to resistance training or returning after a break. For most people the realistic goal during a deficit is preserving muscle rather than gaining it.