# Effects of Intermittent Energy Restriction Alone and in Combination with Sprint Interval Training on Body Composition and Cardiometabolic Biomarkers in Individuals with Overweight and Obesity PMID: 35805627 Journal: International journal of environmental research and public health Published: 2022 Jun 29 Authors: Cooke MB, Deasy W, Ritenis EJ, Wilson RA, Stathis CG ## Question Does combining twice-weekly 5:2 intermittent fasting with low-volume sprint interval cycling produce better body composition and cardiometabolic outcomes than fasting alone or SIT alone? ## Summary In adults with overweight or obesity, 16 weeks of 5:2 intermittent fasting drove most body-weight and fat-mass improvement, while low-volume supervised cycling sprint intervals mainly improved cardiorespiratory fitness. Combining fasting with SIT did not reduce weight or fat more than fasting alone. The SIT protocol was very short and well attended, but it was not enough by itself to meaningfully change body composition or most cardiometabolic biomarkers. ## Population - Adults with overweight or obesity recruited in Melbourne, Australia. - Sample size: 34 - Age: 35.4 +/- 8.4 years overall - Sex: Male and female; final groups were predominantly female - Fitness level: Not in structured training in previous 6 months; baseline VO2peak 27.7 +/- 7.0 mL/kg/min - Health status: Overweight/obese and predominantly metabolically healthy; excluded smokers, chronic disease, pregnancy, menopause/post-menopause, and contraindicating medications/supplements ## Methodology - Randomized three-arm intervention trial - 16 weeks - Free-living diet intervention plus supervised laboratory cycle training - Randomized and controlled study design. ## Protocol - SIT plus 5:2 intermittent fasting. - Modality: Magnetically braked cycle ergometer plus 5:2 fasting diet. - Work intervals: 20 seconds at 150% VO2peak. - Recovery: 40 seconds active rest at 50 W. - Sets or repetitions: 4 repetitions initially, progressed to 6 repetitions. - Intensity: 150% VO2peak for work intervals; HR and Borg RPE monitored. - Session duration: About 10 minutes total including 3 minute warm-up and 3 minute warm-down. - Frequency: SIT 3 sessions/week on non-fasting days; fasting 2 nonconsecutive days/week. - Program length: 16 weeks. - Progression: Workload increased from 4 to 6 repetitions over first 4 weeks and stayed at 6 intervals. - IF alone and SIT alone. - Modality: 5:2 diet alone or cycling SIT alone. - Work intervals: SIT comparator used 20 seconds at 150% VO2peak; IF comparator had no exercise protocol. - Recovery: SIT comparator used 40 seconds active rest at 50 W. - Sets or repetitions: SIT: 4-6 repetitions. - Intensity: SIT: 150% VO2peak; IF: two 500/600 kcal fasting-day meals by sex. - Session duration: SIT about 10 minutes; IF fasting-day dietary restriction. - Frequency: SIT 3 sessions/week; IF 2 fasting days/week. - Program length: 16 weeks. - Progression: SIT repetitions progressed over first 4 weeks; IF diet unchanged. ## Outcomes ### Body weight and fat mass Status: improved IF and IF/SIT reduced body weight and fat mass more than SIT alone, with no significant difference between IF and IF/SIT. Body weight group x time p=0.004; fat mass group x time p=0.002; IF and IF/SIT lower than SIT at 16 weeks p<0.05. ### Visceral adipose tissue Status: mixed VAT decreased significantly within IF/SIT at 16 weeks but between-group differences were not significant. Time effect p=0.001; IF/SIT within-group p=0.004; IF trend p=0.07. ### VO2peak Status: improved Exercise was required for cardiorespiratory fitness gains; SIT and IF/SIT improved VO2peak whereas IF alone did not. Time p=0.001, group p=0.001, group x time p=0.002; SIT p=0.03 and IF/SIT p=0.001 vs IF. ### Blood pressure and biomarkers Status: mixed Blood pressure, lipids, glucose and insulin resistance effects were minimal or mixed; LDL and glucose AUC improved only in IF/SIT in change analyses. No main effects for BP/PWV; LDL reduction in IF/SIT p<0.01; glucose tolerance AUC reduction in IF/SIT p<0.05. ## Practical Insights - Very short cycle SIT can improve VO2peak, but users seeking fat loss likely need diet/energy-balance support or more exercise volume. - Pairing SIT with fasting improved fitness plus some metabolic markers, but did not outperform fasting alone for weight/fat loss. - For app programming, 20-second hard / 40-second easy bike intervals are time-efficient but should be framed as fitness-oriented, not a standalone weight-loss tool. ## Limitations - Small final sample and low male numbers, with pooled sex analysis. - Free-living diet and activity were not tightly controlled. - Self-reported food logs and physical activity measures may be biased. - No continuous energy restriction comparator. - SIT volume may have been too low to test body composition effects. ## Safety And Adherence - No adverse events were reported in the extracted text. - Participants were screened for chronic disease, smoking, pregnancy, menopause, and contraindicating medications. - SIT participants had to attend at least 85% of sessions to remain in final analysis. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/35805627/) (pubmed) - [DOI](https://doi.org/10.3390/ijerph19137969) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9265557/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.