Author(s): TSANG, H., POON, E.T.C., TREXLER, E.T., ZHANG, B., CHENG, Y., QU, Y.J., WONG, S.H.S., ZHENG, C., SUN, F., Institution: THE EDUCATION UNIVERSITY OF HONG KONG, Country: HONG KONG, Abstract-ID: 2083

INTRODUCTION:
Obesity remains a major global public health challenge, contributing to increased metabolic diseases and mortality. Continuous energy restriction (CER), the conventional weight-loss approach, often induces metabolic adaptation, mood disturbances, and poor long-term adherence. Intermittent dieting incorporating short breaks with ad-libitum energy intake (INTB)—commonly termed “cheat meals”—have gained popularity in fitness communities as a potentially viable weight reduction strategy to attenuate these negative effects. This parallel-group, repeated-measures, three-arm randomized controlled trial investigated the effects of INTB on body composition and metabolic adaptation, as compared to the traditional CER approach.
METHODS:
Seventy-seven physically inactive females aged 18-35 years with obesity (BMI ≥25 kg · m-²) were randomized to 8 weeks of either: (1) CER with 70% energy balance daily, (2) INTB with 70% energy balance on 5 days/week and 2 ad-libitum feeding days/week, or (3) control group (CON) maintaining habitual diet (CER: N= 26, 29.8 ± 3.7 years, 75.3 ± 9.8 kg; INTB: N= 26, 29.8 ± 3.4 years, 75.2 ± 12.1 kg; CON: N= 25, 29.8 ± 4.0 years, 74.5 ± 10.7 kg). Body composition and resting metabolic rate (RMR) were assessed at baseline and after the interventions.
RESULTS:
Both CER and INTB produced significant weight loss compared to CON (CER: adjusted mean difference [95% Confidence Interval] −2.8 kg [−3.5 to −2.0]), P < 0.001; INTB: −3.1 kg [−3.9 to −2.3], P < 0.001), with no differences between CER and INTB (P = 0.792). Fat free mass declined significantly in INTB when compared to CER (-0.5 kg [−1.1 to 0], P=0.046). The RMR decreased markedly more in CER than in INTB (-69.9 kcal [−114.3 to −25.5], P < 0.001). No serious adverse events were reported, and adherence was high (80%-85%) across intervention groups.
CONCLUSION:
The CER and INTB produced similar meaningful weight loss over 8 weeks. However, INTB markedly attenuated the adaptive reduction in RMR compared to CER, suggesting a possible physiological advantage for long-term weight management by preserving energy expenditure. These findings support INTB as a promising, flexible alternative to traditional daily energy restriction.