Intermittent fasting two days versus one day per week, matched for total energy intake and expenditure, increases weight loss in overweight/obese men and women

Abstract

Background Intermittent fasting (IF), consisting of either a one-day (IF1) or two consecutive days (IF2) per week, is commonly used for optimal body weight loss. Our laboratory has previously shown an IF1 diet combined with 6d/week of protein pacing (P; 4–5 meals/day evenly spaced, ~ 30% protein/day) significantly enhances weight loss, body composition, and cardiometabolic health in obese men and women. Whether an IF1-P or IF2-P, matched for weekly energy intake (EI) and expenditure (EE), is superior for weight loss, body composition, and cardiometabolic health is unknown. Methods This randomized control study directly compared an IF1-P (n = 10) versus an IF2-P (n = 10) diet on weight loss and body composition, cardiovascular (blood pressure and lipids), hormone, and hunger responses in 20 overweight men and women during a 4-week weight loss period. Participants received weekly dietary counseling and monitoring of compliance from a registered dietitian. All outcome variables were assessed pre (week 0) and post (week 5). Results Both groups significantly reduced body weight, waist circumference, percent body fat, fat mass, hunger, blood pressure, lipids, glucose, and increased percent fat-free mass (p < 0.05). However, IF2-P resulted in significantly greater reductions in body weight (-29%) and waist circumference (-38%) compared to IF1-P (p < 0.05), and showed a strong tendency for greater reductions in fat mass, glucose, and hunger levels (p < 0.10) despite similar weekly total EI (IF1-P, 9058 ± 692 vs. IF2-P, 8389 ± 438 kcals/week; p = 0.90), EE (~ 300 kcals/day; p = 0.79), and hormone responses (p > 0.10). Conclusions These findings support short-term IF1-P and IF2-P to optimize weight loss and improve body composition, cardiometabolic health, and hunger management, with IF2-P providing enhanced benefits in overweight women and men. Trial registration This trial was registered March 03, 2020 at www.clinicaltrials.gov as NCT04327141.

Exploratory analysis of one versus two-day intermittent fasting protocols on the gut microbiome and plasma metabolome in adults with overweight/obesity

“…Moreover, dietary fiber intake significantly increased (8-12 g/d), whereas sugar (-57 to 77 g/d) and sodium (-1,500 to 2,000 mg/d) significantly decreased. As previously reported, both groups maintained similar physical activity and energy expenditure throughout the weight loss period (31).…”

“…Reductions have been observed in other short-term weight loss trials with suggestive susceptibility to food cravings (92). In contrast, these behaviors were not reflected in participants from the present study as hunger ratings significantly improved over baseline levels (31). The other notable negative correlation was fatty acid biosynthesis.…”

Is Intermittent Fasting Better Than Continuous Energy Restriction for Adults with Overweight and Obesity?

“…In a study of healthy adults with overweight and obesity using meal replacements on fasting days, short-term fasting (4 weeks) resulted in greater weight loss and improved body composition and cardiometabolic health without exacerbating the feeling of hunger or adversely affecting appetite. 47 The investigators also found that two days of fasting per week was more beneficial than one day. Higher protein intake and more frequent eating were shown to reduce the amount of total and abdominal fat and improved LBM and postprandial thermogenesis; both were effective for long-term weight maintenance and are feasible for patients with overweight or obesity.…”

“… 60 Short-term (4 weeks) IF decreased body weight and improved body composition and cardiometabolic health while having no adverse effects on the feeling of hunger or appetite, whereas long-term (52 weeks) IF reduced the amount of total and abdominal fat and increased LBM, thereby promoting weight maintenance. 47 , 49 A lower LBM is associated with a lower metabolic rate and neuromuscular function, fatigue, and increased risk of injury, with the degree of LBM reduction positively correlated with weight regain. 61 Thus, a reasonable weight loss goal is to reduce body fat while avoiding loss of muscle mass.…”

“…Compared with a heart-healthy diet, IF with a low-calorie, high-protein diet for one year had certain advantages for cardiometabolic health such as weight reduction, prevention of low-density-lipoprotein rebound, and enhanced arterial compliance. 47 , 64 Meal timing also influences cardiometabolic health; according to the American Heart Association, nighttime fasting can reduce the risk of cardiovascular disease. 8 A study of lean and healthy adults showed that although IF yielded comparable overall weight loss to energy restriction and balanced diets, subjects in the IF group showed less weight loss due to fat reduction and there were no specific benefits in terms of metabolic regulation or cardiovascular health.…”