Figure 10. Effects of CR on body mass and body composition in humans are sex- and age-dependent.

Twenty male and 22 female volunteers participated in a weight loss study involving a 4-week dietary intervention. (A–F) Body mass was recorded each week (A,B). Fat mass (FM) and fat-free mass (FFM) were measured by air-displacement whole-body plethysmography at weeks 0 and 4 (C–F). Body mass, fat mass, and fat-free mass are shown as absolute masses (A,C,E) or fold-change relative to baseline (B,D,F). Data are presented as mean ± SEM. For (A–C) and (E), significant effects of time, sex, and time*sex interaction were assessed using two-way ANOVA. In (B), (D) and (F), significant differences between males and females at each time point were determined by Šídák’s multiple comparisons test (B) or unpaired T-test (D,F) and are indicated by * (p<0.05) or ** (p<0.01). (G–I) Simple linear regression of age vs fold-change (week 4 vs week 0) in body mass (G), fat mass (H) and fat-free mass (I). For each sex, significant associations between age and outcome (fold-change) are indicated beneath each graph as ‘P, Slope’. ANCOVA was further used to test if the age-outcome relationship differs significantly between males and females. ANCOVA results are reported beneath each graph as ‘P, Slope’ and ‘P, Intercept’ for males vs females (M vs F). In (G), similar slopes but different intercepts show that sex significantly influences weight loss, but the influence of age does not differ between the sexes. In (H,I) the slopes differ significantly, indicating that the age-outcome relationship differs between the sexes. (J–L) Fold-change (week 4 vs week 0) in body mass (J), fat mass (K) and fat-free mass (L) for males vs females separated into younger (<45 years) and older (>45 years) groups. Data are presented as violin plots overlaid with individual data points. Significant effects of age, sex, and age*sex interaction were assessed using two-way ANOVA with Tukey’s multiple comparisons test. Overall p values for each variable, and their interactions, are shown beneath each graph. Significant differences between comparable groups are indicated by * (p<0.05) or *** (p<0.001). Source data are provided as a Source Data file. See also Table 2 and Figure 10—figure supplements 1–3.

Figure 10—figure supplement 1. Baseline fat mass or BMI do not influence sex differences in the effects of CR on body mass or body composition.

Twenty male and twenty-two female volunteers participated in a weight loss study involving a 4-week dietary intervention, as described for Figure 10. (A–F) Simple linear regression of baseline fat mass (A–C) or baseline BMI (D–F) vs fold-change (week 4 vs week 0) in body mass (A,D), fat mass (B,E) and fat-free mass (C,F). For each sex, significant associations between age and outcome (fold-change) are indicated beneath each graph as ‘P, Slope’. ANCOVA was further used to test if the age-outcome relationship differs significantly between males and females. ANCOVA results are reported beneath each graph as ‘P, Slope’ and ‘P, Intercept’ for males vs females (M vs F). Similar slopes but different intercepts show that sex significantly influences weight loss, but the influence of baseline fat mass or BMI does not differ between the sexes. See also Table 2. Source data are provided as a Source Data file.

Figure 10—figure supplement 2. CR-induced fat loss in mice is age- and sex-dependent.

Male and female mice were fed AL or CR diets from 9 to 15 or 78–84 weeks of age and fat mass was determined each week, as described for Figures 2 and 7. For each mouse (CR and AL diets), the ratio of absolute fat masses (g) was calculated for week 4 vs week 0 (i.e. 13 vs 9 weeks of age for young mice; 82 vs 78 weeks for aged mice); week 4 was selected for consistency with the 4-week duration of our human CR study (Figure 9). For the CR mice, the fold-change in fat mass, relative to AL mice, was then determined as follows: (i) the mean week 4:week 0 ratio was calculated for AL mice in each age group; (ii) within each sex and age group, the week 4:week 0 ratio for each CR mouse was calculated relative to the mean week 4:week 0 ratio for the corresponding AL group. The rationale for showing these ‘fold changes of fold changes’ is that the AL mice gain fat mass over the course of the study and therefore we must determine how much the fat mass of each CR mouse has changed compared to where we would expect it to be if it had continued on AL diet. Data in are shown as violin plots of the following numbers of mice per group: young female, n=31; young male, n=26; old female, n=11; old male, n=9. Significant effects of diet and/or sex were determined by two-way ANOVA with Tukey’s multiple comparisons test and are reported as described for Figure 2—figure supplement 2. Source data are provided as a Source Data file.

Figure 10—figure supplement 3. Body fat percentage in human CR participants.

Twenty male and twenty-two female volunteers participated in a weight loss study involving a 4-week dietary intervention, as described for Figure 10. Total % fat mass at week 0 is shown for males vs females separated into younger (<45 years) and older (>45 years) groups. Data are presented as violin plots overlaid with individual data points. Significant effects of age, sex, and age*sex interaction were assessed using two-way ANOVA with Tukey’s multiple comparisons test. Overall p values for each variable, and their interactions, are shown beneath the graph. Significant differences between comparable groups are indicated by ** (p<0.01) or *** (p<0.001). See also Table 2. Source data are provided as a Source Data file.