Prolonged water‐only fasting followed by a whole‐plant‐food diet promotes fat‐free mass recovery and continued fat mass loss in adults with overweight or obesity

Conventional weight-loss strategies often result in inadequate fat loss,
poor sustainability, and unintended lean mass loss. Prolonged water-only
fasting followed by dietary change may offer an effective alternative, but
its impact on body composition remains underexplored. This secondary
analysis utilized dual-energy X-ray absorptiometry (DXA) to assess changes
in fat-free mass (FFM), fat mass (FM), and bone mineral content (BMC) in
adults [median (IQR) age: 62 (15) years] with overweight or obesity.
Participants underwent a median (IQR) of 14 (6) days of water-only
fasting, followed by 6 (3) days of food reintroduction with a
whole-plant-food diet and a subsequent maintenance period of 45 (5) days.
Study visits occurred at baseline and at the end of each period. At the
end of fasting, FFM accounted for 74% of the total BW lost during fasting.
However, at the follow-up visit, the median (IQR) percentage change in
total BW, FFM, FM, and visceral adipose tissue (VAT) mass from baseline
was -8.2 (5.2), -4.4 (5.6), -14.7 (8.9), and -15.8 (12.8) %, respectively.
At follow-up, FM loss accounted for 67% of total BW lost. BMC remained
unchanged across all study visits. This protocol produced sustained FM
loss, specifically VAT mass, and FFM recovery, suggesting it may support
effective weight management.