Muscle doesn’t turn into fat—it shrinks—but inactivity can lead to fat gain if calories aren’t controlled
Malaysian gym-goers warned: Muscle loss and fat gain after exercise breaks are separate processes, say experts
Source: The Guardian World · October 12, 2026 at 3:32 PM · AI-assisted report
Single-sourceKUALA LUMPUR, 12 OCTOBER 2026 —
Malaysian gym-goers warned: Muscle loss and fat gain after exercise breaks are separate processes, say experts
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A leading muscle physiologist has debunked the common myth that muscle "turns into fat" when people stop working out, clarifying that the two tissues are distinct and the perceived change is due to separate biological processes. Professor Leigh Breen, a specialist in muscle physiology at the University of Leicester, said the misconception stems from simultaneous muscle loss and fat accumulation during periods of inactivity.
The confusion arises because prolonged exercise breaks—particularly without resistance training—can lead to muscle atrophy while an unchanged diet may result in fat storage. "There’s no known process in the human body that would support muscle turning into fat, or vice versa," Breen stated. Instead, he explained that reduced activity triggers muscle breakdown, while excess calories from the same diet can be stored as fat.
"This combination of a reduction in muscle mass and potentially an increase in fat mass can give the impression that one is turning into the other," he added.
Breen noted that short breaks—such as a couple of weeks off training while remaining active—typically cause fewer changes than extended immobilisation, such as injury recovery. Diet also plays a critical role: maintaining high protein intake while slightly reducing overall calories can mitigate muscle loss and fat gain during breaks. "Slight fluctuations are generally nothing to worry about, as long as consistent exercise and dietary habits have been maintained over months and years," he said.
The clarification comes amid rising interest in fitness among Malaysians, with gym memberships and home workouts surging post-pandemic. Experts warn that abrupt halts in exercise—without dietary adjustments—can lead to visible changes in body composition, even if muscle and fat remain separate tissues. Breen’s research underscores the importance of structured recovery periods, noting that temporary muscle loss is reversible with resumed training and proper nutrition.
For those concerned about maintaining fitness during breaks, the professor recommended gradual tapering of activity rather than abrupt cessation, alongside protein-rich diets to preserve muscle. "Our bodies are constantly changing, and small fluctuations are normal," he said, emphasising that long-term consistency matters more than short-term setbacks. The advice aligns with broader health guidelines in Malaysia, where lifestyle diseases linked to sedentary habits remain a public health priority.
Related: Professor Leigh Breen