High Fat Diet Increases HDL & Weight Loss Intermittent energy restriction improves weight loss efficiency
in obese men: the MATADOR study
To examine whether intermittent energy restriction (ER) improved weight loss efficiency compared with continuous ER and, if so, whether intermittent ER attenuated compensatory responses associated with ER.
The MATADOR (Minimising Adaptive Thermogenesis And Deactivating Obesity Rebound) study examined whether intermittent energy restriction (ER) improved weight loss efficiency compared with continuous ER and, if so, whether intermittent ER attenuated compensatory responses associated with ER. Fifty-one men with obesity were randomised to 16 weeks of either: (1) continuous (CON), or (2) intermittent (INT) ER completed as 8 × 2 – week blocks of ER alternating with 7 × 2 – week blocks of energy balance (30 weeks total). Forty-seven participants completed a 4 – week baseline phase and commenced the intervention (CON: N = 23, 39.4 ± 6.8 years, 111.1 ± 9.1 kg, 34.3 ± 3.0 kg m− 2; INT: N = 24, 39.8 ± 9.5 years, 110.2 ± 13.8 kg, 34.1 ± 4.0 kg m− 2). During ER, energy intake was equivalent to 67% of weight maintenance requirements in both groups. Body weight, fat mass (FM), fat-free mass (FFM) and resting energy expenditure (REE) were measured throughout the study. For the N = 19 CON and N = 17 INT who completed the intervention per protocol, weight loss was greater for INT (14.1 ± 5.6 vs 9.1 ± 2.9 kg; P<0.001). INT had greater FM loss (12.3 ± 4.8 vs 8.0 ± 4.2 kg; P<0.01), but FFM loss was similar (INT: 1.8 ± 1.6 vs CON: 1.2 ± 2.5 kg; P = 0.4). Mean weight change during the 7 × 2 - week INT energy balance blocks was minimal (0.0 ± 0.3 kg). While reduction in absolute REE did not differ between groups (INT: -502 ± 481 vs CON: − 624 ± 557 kJ d − 1; P = 0.5), after adjusting for changes in body composition, it was significantly lower in INT (INT: − 360 ± 502 vs CON: − 749 ± 498 kJ d − 1; P<0.05). Greater weight and fat loss was achieved with intermittent ER. Interrupting ER with energy balance ‘rest periods’ may reduce compensatory metabolic responses and, in turn, improve weight loss efficiency.
In conclusion, intermittent ER, delivered as alternating 2-week blocks of ER and energy balance, resulted in greater weight loss (fat loss) without greater loss of FFM, attenuation of the reduction in REE, and superior weight loss retention after 6 months, compared with an equivalent ‘dose’ of continuous ER. While adaptive reductions in REE were attenuated using this 2:2 intermittent ER approach, it is possible that greater weight loss in the INT group may also be due to reduced compensation in other energetic functions such as the thermic effect of food and activity energy expenditure. Additionally, there is the need to investigate the effectiveness of this dietary approach when individuals are not provided meals in a tightly controlled metabolic study. Therefore, while additional work is needed to further investigate the mechanistic bases for this novel intermittent approach, these findings provide preliminary support for the model as a superior alternative to continuous ER.