Why has my grip and absolute strength fallen off a cliff when my DEXA shows almost no lean-mass loss?

Accepted answer

Nothing is wrong with your scan. Strength is not a function of muscle cross-sectional area alone, and almost every non-size contributor to force production is degraded by a sustained energy deficit. Your numbers reconcile once you account for them.

Decomposing a 20% strength loss

Force output at the barbell is roughly the product of contractile tissue, neural drive, and the mechanical and metabolic conditions of the moment. Attributable causes, in rough order of size for your situation:

• Neural drive and skill. Maximal voluntary force depends on motor-unit recruitment, firing rate, and inter-muscular coordination. All of these are trainable, all of them are fatigue-sensitive, and all of them decay when you train under chronic under-recovery even if you keep showing up. This is typically the largest single contributor to strength loss in a deficit and it is fully reversible within weeks of restoring energy.
• Muscle glycogen. Depleted muscle produces less force, particularly on sets above about three reps and particularly for large-mass movements like a deadlift. Going from a full 500 g of stored glycogen to 250 g measurably reduces high-threshold output. Your five-rep deadlift is exactly the kind of effort this hits.
• Intramuscular water and cell volume. Sarcoplasmic volume contributes to the mechanical stiffness of the force-transmitting apparatus. A dehydrated, glycogen-depleted muscle is a softer spring.
• Tendon and connective tissue stiffness. Force transmission depends on the series elasticity between muscle and bone. Tendon adaptation is slow and appears to be sensitive to nutritional status. A compliant tendon transmits less of what the muscle generates.
• Body mass itself. This is the one people forget for the deadlift and squat. Absolute strength scales sub-linearly with body mass, so losing 19 kg genuinely reduces your absolute lifting capacity even with muscle fully preserved. Allometric scaling, using the two-thirds power of body mass, gives a rough estimate:

Expected strength ratio = (new mass / old mass) ^ (2/3)
  = (82 / 101) ^ 0.667
  = (0.812) ^ 0.667
  = 0.87

Predicted deadlift from mass change alone: 150 x 0.87 = 130 kg
You are at 120 kg. Unexplained gap: about 8%.

So more than half of your apparent 20% deadlift loss is a straightforward consequence of being a smaller person, and it is not a loss of anything you want back. The residual 8% is the part attributable to neural drive, glycogen and recovery, and that part is recoverable.

Why grip specifically

Grip is the most sensitive strength measure to systemic state, which is exactly why it is used as a frailty and clinical-outcome marker rather than as a measure of forearm size. Contributors in your case:

• The forearm flexors are small-mass, high-endurance-fibre muscles with limited glycogen buffering, so they degrade early under low availability.
• Grip is measured at a single maximal instant with no momentum or technique to hide behind, so it exposes neural drive more directly than a multi-joint lift does.
• Grip is downstream of total-body arousal: sleep debt, low blood glucose and central fatigue all reduce it acutely. A 10 kg dynamometer drop can be produced by a bad fortnight, not just by seven months.

Retest the dynamometer under good conditions: well slept, fed, warm hands, after a couple of submaximal practice squeezes, best of three, same hand and posture as the original. A meaningful fraction of your 54 to 44 will come back on that test alone. What remains is real.

The pull-up number is the one to act on

Losing 4 reps while shedding 19 kg means your absolute pulling force fell by considerably more than the allometric prediction. That is the signal in your post that is not explained by getting smaller, and it points at either under-recovery or a genuine reduction in upper-body contractile tissue that a whole-body lean number can hide. Ask for the regional breakdown on your DEXA: arms, legs and trunk lean mass are reported separately, and appendicular lean mass is the number that matters. A whole-body figure that is flat can conceal 1 kg lost from the arms and 0.5 kg gained in trunk water.

What I would change

You are eating 145-160 g of protein, so protein is not the problem. The likely problems are total energy and recovery. Concretely: report your total intake, get sleep duration onto a measured basis for two weeks, and try a two-week period at maintenance energy with unchanged training. If most of the strength returns in two weeks, it was never tissue. That is a diagnostic worth running before you conclude anything about muscle loss.

edited 6 Oct 2025 by plate_count_9k — added the placebo-arm figures