Obese women who performed resistance training while on a very low-calorie liquid diet for 90 days gained muscle fiber size in both slow-twitch and fast-twitch fibers, despite losing an average of 16 kg. Sedentary women on the same diet did not see any change in muscle fiber size.
See the scientific wording
Resistance training during severe energy restriction (3360 kJ/day liquid diet) over 90 days is associated with increased cross-sectional area of both slow-twitch and fast-twitch muscle fibers in obese females, demonstrating that muscle hypertrophy can occur despite a large average weight loss of 16 kg, with no change in fiber size observed in sedentary individuals.
Backed by science
Randomized trialsOne low-scoring study supports this claim, so treat this as an early signal rather than settled science.
What the research says
1 study reviewedSupporting (1)
Muscle hypertrophy with large-scale weight loss and resistance training.
Randomized Controlled TrialHuman1993
The study found that obese women who did weight training while on a very low-calorie diet built bigger muscle fibers, but those who didn't exercise did not, proving that muscle growth is possible even during major weight loss.
Contradicting (0)
No contradicting studies found yet
That doesn't mean it's settled — it just means no study has tested the opposite.
Quality-weighted scoring: we follow the GRADE framework — each study is rated High, Moderate, Low, or Very Low based on study design, methodology rigor, and risk of bias. A single high-quality RCT can outweigh several weaker observational studies.
Scores reflect study quality, not just count.
Weight training pulls on muscle fibers. This pulling activates sensors inside the fibers that turn on growth signals. These signals tell the muscle to build more protein, making the fibers bigger. This happens even when the body is not getting enough food because the exercise signal is strong enough to override the energy shortage.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting study
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Obese women who performed resistance training while on a very low-calorie liquid diet for 90 days gained muscle fiber size in both slow-twitch and fast-twitch fibers, despite losing an average of 16 kg. Sedentary women on the same diet did not see any change in muscle fiber size.
Mechanism
1 studyThe main way this works is that lifting weights creates a strong pull on the muscles. This pull turns on growth signals inside the muscle cells. These growth signals make the muscle build new protein, which makes the fibers thicker. This happens even when the person is eating very little, because the exercise signal is powerful enough to overcome the lack of food.
Weight training pulls on muscle fibers. This pulling activates sensors inside the fibers that turn on growth signals. These signals tell the muscle to build more protein, making the fibers bigger. This happens even when the body is not getting enough food because the exercise signal is strong enough to override the energy shortage.
Weight training imposes mechanical tension on muscle fibers, activating mechanoreceptors such as integrins and focal adhesion kinase.
Mechanotransduction activates anabolic signaling pathways, including mTORC1, which promotes muscle protein synthesis.
Enhanced muscle protein synthesis results in hypertrophy of both slow-twitch and fast-twitch fibers, increasing their cross-sectional area.
Evidence from Studies
Supporting (1)
Community contributions welcome
Muscle hypertrophy with large-scale weight loss and resistance training.
The study found that obese women who did weight training while on a very low-calorie diet built bigger muscle fibers, but those who didn't exercise did not, proving that muscle growth is possible even during major weight loss.
Contradicting (0)
Community contributions welcome
Score Breakdown
No multi-axis breakdown available yet. The overall Pro / Against score above is the best signal.
- No clinical evidence is available; the score reflects mechanistic plausibility only.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
Systematic Review of RCTs on Resistance Training During Severe Energy Restriction in Obese Females
Systematic review with meta-analysis of randomized controlled trials comparing resistance training plus severe energy restriction (≤3360 kJ/day) versus severe energy restriction alone in obese females, with outcomes including muscle fiber cross-sectional area, body composition, and muscle strength.
RCT: Resistance Training vs No Training During 90-Day Liquid Diet in Obese Women
Randomized controlled trial with two arms: (1) resistance training 3x/week plus 3360 kJ/day liquid diet, (2) no exercise plus same liquid diet, over 90 days in obese females (BMI ≥30). Primary outcome: muscle fiber cross-sectional area from biopsy.
Cohort Study: Muscle Fiber Changes in Obese Women on Very Low-Calorie Diet With and Without Resistance Training
Prospective cohort study of obese women undergoing a 90-day very low-calorie liquid diet (3360 kJ/day), comparing those who self-select resistance training vs those who do not, with muscle biopsies at baseline and 90 days.