IL6 and infection: The trial will enroll participants meeting the following inclusion criteria: (1) ≥ 70 years of age, (2) with low to moderate physical function, defined as self-reported difficulty walking 1/4 mile or climbing a flight of stairs, but able to walk 400 m at baseline exam, (3) usual walking speed between ≥ 0.44 and < 1.0 m/s on a 4-m walk or a body mass index of ≥ 28 kg/m<sup>2</sup>, (4) average IL-6 level between 2.0 and 30 pg/mL on two tests, and (5) no active infection, cancer, or other serious health conditions.