Intermittent fasting without a growling stomach — how can you do it without suffering?

Aim of the study: This study compared intermittent fasting and protein pacing (IF-P) versus a heart-healthy caloric restriction (CR) diet, matched for energy intake and physical activity energy expenditure, on body weight, total and visceral fat mass, and cardiometabolic health outcomes in adults with obesity.

Results: Both groups reduced (p < 0.05) weight, total and visceral fat mass, blood pressure and lipids, and desire to eat food and increased proportion of fat-free mass. IF-P resulted in greater (p < 0.05) reductions in weight (-9% vs. -5%), total (-16% vs. -9%) and visceral (-33% vs. -14%) fat mass, and desire to eat (-17% vs. 1%) and increased fat-free mass percent (6% vs. 3%) compared with CR. These improvements were despite similar weekly total energy intake (IF-P, 9470 ± 550 vs. CR, 9095 ± 608 kcal/wk; p = 0.90) and physical activity energy expenditure (IF-P, 300 ± 150 vs. CR, 350 ± 200 kcal/d; p = 0.79). IF-P and CR optimize weight loss, body composition, cardiometabolic health, and hunger management, with IF-P providing greater benefits.

Aim of the study: Daily caloric restriction (DCR) is a common dietary weight loss strategy, but leads to metabolic and behavioral adaptations, including maladaptive eating behaviors and dysregulated appetite. Intermittent fasting (IMF) may mitigate these effects by offering diet flexibility during energy restriction.

Results: Included in this analysis were 165 adults (mean ± SD; age 42 ± 9 years, BMI 34.2 ± 4.3 kg/m2, 74% female) randomized to 4:3 IMF (n = 84) or DCR (n = 81). At 12 months, binge eating and uncontrolled eating scores decreased in 4:3 IMF but increased in DCR (p < 0.01 for between-group differences). Among 4:3 IMF, greater weight loss was associated with decreased uncontrolled eating (r = -0.27, p = 0.03), emotional eating (r = -0.37, p < 0.01), and increased cognitive restraint (r = 0.35, p < 0.01) at 12 months. There were no between-group differences in changes in fasting appetite-related hormones at any time point. Compared to DCR, 4:3 IMF exhibited improved binge eating and uncontrolled eating behaviors at 12 months. This may, in part, explain the greater weight loss achieved by 4:3 IMF versus DCR. Future studies should examine mechanisms underlying eating behavior changes with 4:3 IMF and their long-term sustainability.

Aim of the study: The Ramadan fast imposes abstinence from food and water during daytime for 28-29 days, providing an ecological model of prolonged intermittent dry fasting. Longitudinal data characterizing hunger, thirst, and hydration trajectories across fasting and recovery remain limited.

Results: Hunger declined significantly at Ramadan onset and remained suppressed one month post-Ramadan (medium effect, η2 = 0.067), with a more rapid within-sex decline in women (η2 = 0.098 vs. 0.038). The sexes differed significantly only at one-month recovery, when women reported higher hunger (medium effect, Cramér's V = 0.21). Thirst rose incrementally, remained elevated through late fasting, then fell below pre-Ramadan baseline after fasting (medium effect, η2 = 0.071). Peak appetite timing was delayed during Ramadan and returned to baseline post-Ramadan (small effect, η2 = 0.052). Fluid intake rose post-Ramadan, earlier in men (small effect, η2 = 0.04). Normalized intake was higher in women throughout in the Muslim group and at 3 timepoints in controls. Controls showed no comparable transition-specific changes, though a small omnibus reduction in hunger was observed (small effect, η2 = 0.051).

Aim of the study: 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.

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). 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.

Aim of the study: Time-restricted eating (TRE) has gained attention for weight loss and cardiometabolic health improvement. The Time-Restricted Intake of Meals (TRIM) study was a 12-week randomized isocaloric and eucaloric feeding trial comparing 10-h TRE to a 16-h usual eating pattern (UEP) in adults with obesity and either prediabetes or diet-controlled type 2 diabetes.

Results: Thirty-nine participants (19 TRE; 20 UEP) were analyzed, with a mean (SD) age of 60 (7) years and BMI of 35.2 (6.0) kg/m2. Weight loss was similar across groups (2.7% TRE; 2.5% UEP). Both arms increased restraint and decreased disinhibition and hunger. No statistically significant between-group differences were observed in eating behavior, appetite hormones, and inflammatory markers. Both 10-h TRE and 16-h UEP promoted improvements in eating behavior in the context of modest and equivalent weight loss. Larger prospective studies are needed to confirm whether clinically meaningful differences exist.