Figure 2A Left, Body weights of male WT and FADD-D mice on either a SD (n = 8 for each genotype) or a HFD (n = 6 for each genotype). Right, Food intake per mouse fed a HFD measured over 20 days normalized by body weight (n = 10 for each genotype). Results are means ± SEM. *P = 0.0007 (Student's t-test). B Representative photographs of fat pads and organs of 10-week-old male FADD-D and WT mice. C Left, fat pad weights as a percentage of body weight (BW) and in absolute amounts (inset) from male FADD-D and WT mice. Mice were fed a SD or a HFD until 15 weeks of age (n = 6 for each genotype). Results are means ± SEM. *P = 0.0012, **P = 0.0002, ***P = 0.0027, ****P = 0.0014, ^P = 0.0038, ^^P = 0.0019, #P = 0.0045, ##P = 0.0007, *^P = 0.0252, *^^P = 0.0082, ###P = 0.0275, ####P = 0.0071 (one-way ANOVA). Middle, fat pad weights of male FADD-D and WT mice on a HFD at 30 weeks of age (n = 6 for each genotype). Inset, triacylglycerol (TAG) content in epididymal WAT. Data are expressed as means ± SEM. *P = 0.0003, **P = 0.0005, ***P = 0.0019, ****P = 0.0011 (Student's t-test). Right, weight of liver normalized by body weight for male FADD-D and WT littermates at the age of 15 weeks (n = 6 for each genotype). Data are expressed as means ± SEM. NS, not statistically significant (Student's t-test). Epi, epididymal fat; Ren, renal fat; Ing, inguinal fat. C Left, fat pad weights as a percentage of body weight (BW) and in absolute amounts (inset) from male FADD-D and WT mice. Mice were fed a SD or a HFD until 15 weeks of age (n = 6 for each genotype). Results are means ± SEM. *P = 0.0012, **P = 0.0002, ***P = 0.0027, ****P = 0.0014, ^P = 0.0038, ^^P = 0.0019, #P = 0.0045, ##P = 0.0007, *^P = 0.0252, *^^P = 0.0082, ###P = 0.0275, ####P = 0.0071 (one-way ANOVA). Middle, fat pad weights of male FADD-D and WT mice on a HFD at 30 weeks of age (n = 6 for each genotype). Inset, triacylglycerol (TAG) content in epididymal WAT. Data are expressed as means ± SEM. *P = 0.0003, **P = 0.0005, ***P = 0.0019, ****P = 0.0011 (Student's t-test). Right, weight of liver normalized by body weight for male FADD-D and WT littermates at the age of 15 weeks (n = 6 for each genotype). Data are expressed as means ± SEM. NS, not statistically significant (Student's t-test). Epi, epididymal fat; Ren, renal fat; Ing, inguinal fat. D Weight of brown adipose tissue normalized by body weight (n = 5 for each genotype). Data are expressed as means ± SEM. *P = 0.0008 (Student's t-test). E MRI of body fat content: standard non-fat-suppressed (left), fat-suppressed (middle) and fat-only (right). Representative images of three independent experiments (n = 6 total for each genotype) showing similar results are shown. F Paraffin-embedded sections of WAT and BAT from WT and FADD-D mice were stained with H&amp;amp;E. Scale bar = 50 μm. Shown are typical results from four different fields and three different experiments. G Left, relative amounts of liver and muscle triacylglycerol contents in 10-month-old WT and FADD-D mice (n = 6 for each genotype). Right, relative amounts of cholesterol in the liver and muscle of the same group of WT and FADD-D mice (n = 6 for each genotype). Data are expressed as means ± SEM. *P = 0.0015, **P = 0.0027, ***P = 0.0318 (Student's t-test). NS, not statistically significant. H Left, plasma triacylglycerol levels in 10-month-old WT and FADD-D mice following fasting for 20 h (n = 5 for each genotype). Right, plasma cholesterol levels in the same group of WT and FADD-D mice (n = 5 for each genotype). Data are expressed as means ± SEM. *P = 0.0124 (Student's t-test). NS, not statistically significant.