This week, we explore ‘lean mass sparing’ during periods of calorie restriction (CR) in athletes.

CR creates a catabolic environment (breakdown), where weight training creates an anabolic environment (growth). It’s been recommended to reduce training load during CR to better support recovery as there’s less energy available, which makes sense…

However, is it wise to reduce this well-known anabolic stimulus to support recovery when you’re in a greater catabolic state and favouring ‘breakdown’ during CR?

On average, if you restrict calories to drop body fat without a weight training stimulus, 24% of weight loss will be attributed to lean mass. When a weight training stimulus is added, losses in lean mass reduce to 11% (Weinheimer et al, 2010).

Therefore, weight training is incredibly important in sparing lean mass. That being said, can recommendations be fine-tuned to further minimise this loss?

Muscle growth occurs when muscle protein synthesis (MPS) exceeds muscle protein breakdown (MPB). Knowing this, if MPB exceeds MPS, muscle loss will occur.

MPS is an energy expensive process, therefore rates of MPS decline during CR to preserve energy. However, a high protein diet and weight training stimulus are potent activators of MPS and can help offset loss in lean mass.

Weight training volume (weight x reps x sets) plays an important role in training adaptations, and in some instances higher training volumes are necessary for advanced lifters to maximise hypertrophy.

Roth et al (2022) examined how much training volume is needed to spare lean mass during a dieting phase.

In their review, they found that progressively increasing volume over time was most effective in sparing lean mass as opposed to (1) reducing volume, and (2) having a consistently high training volume (possibly from inducing a progressive novel stimulus over time).

Interestingly, (1) females tend to spare more lean mass than men during CR; (2) both sexes may be at heightened risk of lean mass loss when at very low body fat percentages, (3) larger CR induces more lean mass loss – most likely because the anabolic stimulus from training cannot overcome the catabolic state from large energy deficits.

Therefore, muscle mass sparing = Small energy deficit + high protein + progressive weight training.

Ultimately, if you adopt the opposing strategy, muscle mass loss during CR will accelerate.