Severe energy restriction during weight loss leads to a disproportionate loss of muscle and bone mass, thereby increasing the risk of fragility and sarcopenia with age.

noli's read

Stuart Phillips' advice is based on a solid understanding of metabolic physiology. Research, notably the cited study (RCT published in 'Obesity'), confirms that an overly aggressive caloric deficit compromises lean mass more than moderate restriction. While the body requires energy to maintain its tissues, an overly abrupt drop in intake forces the organism to draw from its muscle reserves. Meta-analyses on the subject confirm that pairing weight loss with an adequate protein intake and resistance physical activity is essential to preserve structural tissues. What is sometimes exaggerated in general wellness discourse is the fear of any restriction, whereas science highlights above all the importance of the rate of loss and nutritional quality. The point is scientifically robust: protecting muscle and bone capital is a pillar of longevity.

the sources

No named source held this one up — that absence is part of the verdict.