Clenbuterol gains faded after drug and training stopped
In short
Clenbuterol added 1.7 kg of lean mass gains over placebo during 8 weeks of lifting. After withdrawal and 16 weeks off training, the lean-mass and bench advantages disappeared; leg press stayed higher. Fat loss did not differ between groups.
The extra lean mass was not a lasting head start. After clenbuterol use ended and participants stopped training, their initial lean-mass and bench press gains no longer differed from placebo. Leg press strength remained higher, so the finding is about losing much of an advantage, rather than erasing every benefit or every kilogram gained.
What survived the break, and what did not?
The University of Copenhagen randomized 32 healthy adults, 16 men and 16 women, to clenbuterol or placebo, with 16 participants per group, in a double-blind trial. There were 8 weeks of resistance training, 16 weeks of detraining after drug cessation, and 8 weeks of retraining. DXA assessed body composition; bench press and leg press 1RM assessed strength before and after each phase.
| Phase | Lean mass versus placebo | Strength versus placebo |
|---|---|---|
| 8 weeks training | +1.7 kg additional gain | Bench +6 kg; leg press +16 kg additional gain |
| 16 weeks detraining after withdrawal | Initial gain no longer different | Bench advantage lost; leg press remained higher |
| 8 weeks retraining | No difference in gain | Bench +3 kg additional gain; no difference in leg press gain |
The initial effects on lean mass and bench press were larger in men than women. During retraining, previous exposure did not produce greater lean-mass gains. Also keep the measurement in view: DXA lean mass is not a direct measurement of muscle tissue alone. The trial does not establish a permanent reserve of extra muscle.
Did the supposed fat-loss drug reduce more fat?
Fat mass fell during the 8-week training phase, but the decrease did not differ between clenbuterol and placebo. An extra 1.7 kg of lean-mass gain is not evidence of extra fat loss. The follow-up also combined drug withdrawal with detraining: it cannot tell a lifter exactly what would happen if the drug stopped while training continued.
Clenbuterol is not approved for human performance enhancement or weight loss in Korea and most countries, and is on the WADA Prohibited List. This trial was supervised.
What should a drug-free lifter record?
- Mark training dates and breaks so a past peak is distinguishable from current performance.
- Record each actual Big 3 1RM; do not convert leg press strength into a squat result.
- Compare return-to-training entries under similar conditions and use measured lifts to check Muscle Index.
For fairlift, progress belongs in a history of training-earned lifts. The Muscle Index calculator can put current Big 3 records into a relative strength score, but a peak alone cannot show what happened during a break. Keep the declining entries and the return as well. That is a practical logging takeaway, not a claim that this study tested fairlift or measured squat and deadlift strength.
Frequently asked questions
Do all extra gains disappear after stopping clenbuterol?
After withdrawal and 16 weeks of detraining, initial lean-mass and bench press gains no longer differed from placebo, but leg press strength remained higher. The trial did not test withdrawal while participants continued training.
Did clenbuterol produce greater fat loss?
During 8 weeks of resistance training in 32 healthy adults, fat-mass reduction did not differ between clenbuterol and placebo. The additional 1.7 kg of lean-mass gain is a separate outcome from fat loss.
Did previous users gain more muscle when training resumed?
During 8 weeks of retraining, lean-mass and leg press 1RM gains did not differ between groups. Bench press 1RM improved by an additional 3 kg in the former clenbuterol group compared with placebo.
Source: PubMed (published )