Effects of 16 weeks of Intermittent Fasting and Sprint Interval Training on BMI and Mood State

Objective: Intermittent fasting (IF) and sprint interval training (SIT) are weight loss and exercise strategies that are popular within the health and lifestyle communities. These protocols are extensively studied, and while their somatic effects are well documented there has been limited exploration of psychological effects. This necessitates investigation of the effects of these protocols on quality of life and mood state. 

Methods: Thirty-four participants ( age: 35.4,  BMI: 31.3 kg/m2) were randomized into one of three 16-week interventions: (1) 5:2 IF (2 non-consecutive days of energy restriction per week, 5 days ad libitum energy intake), (2) SIT (3 sessions per week: 4-6 bouts of 20s cycling @ 150% VO2peak followed by 40s of active rest), and (3) a combination of both interventions (IF/SIT). BMI was measured at 0, 8 and 16 weeks. Mood state was assessed weekly using the profile of mood states (POMS) to quantify indices of tension, depression, anger, fatigue, confusion, vigour, and total mental disturbance (TMD). Calorie intake was monitored using a four-day food diary (3 non-fasting days, 1 fasting day). 

Results: BMI decreased significantly in both the fasting groups compared to SIT (p < 0.05), with no significant difference between the fasting groups. No significant changes were detected in calorie intake or levels of depression, fatigue, tension, confusion, vigour, anger, or TMD after 16-weeks of fasting within or between groups. 

Conclusions: These results indicate that IF and IF/SIT are effective strategies for weight loss without exerting a negative effect on participant’s mood and emotional state.