Obesity contributes to disability in older adults, and this is offset by weight loss and exercise. Very Low Calorie Diets (VLCDs) achieve rapid weight loss; however, these have not been rigorously evaluated in older people.A randomized trial was conducted from August 2012 through December 2015. The intervention was 12 weeks of thrice weekly exercise combined with either healthy eating advice (Ex/HE), hypocaloric diet (Ex/Diet), or VLCD (Ex/VLCD). Outcomes were physical function, measured by 6-minute walk test (6MWT) and De Morton Mobility Index (DEMMI). Other measures were body composition measured by Dual Energy X-Ray Absorptiometry, and nutritional parameters (albumin, vitamins B12 and D, ferritin and folate).36, 40, and 41 participants were randomized to Ex/HE, Ex/Diet, and Ex/VLCD, respectively. At 12 weeks, weight was reduced by 3.7, 5.1, and 11.1% (p < .01), respectively. Ex/VLCD had significant reduction in fat (16.8%), lean mass (4.8%), and bone mineral density (1.2%), but increased relative lean mass (3.8%). DEMMI improved by 14.25, 14.25, and 13.75 points in Ex/HE, Ex/Diet, and Ex/VLCD, respectively; however, there was no between-group difference (p = .30). 6MWT improved by 53.1, 64.7, and 84.4 meters in Ex/HE, Ex/Diet, and Ex/VLCD (p = .18). Post hoc stratification for gender and adjustment for initial physical function and type 2 diabetes only revealed significant between-group differences for men in the 6MWT, with improvement by 57.8, 77.8, and 140.3 meters in Ex/HE, Ex/Diet, and Ex/VLCD, respectively (p = .01). Improvements in nutritional parameters were seen in Ex/VLCD, but not in Ex/HE and Ex/Diet. The VLCD was well tolerated.VLCDs have potential in the treatment of obesity in older persons; of particular benefit is improvement in nutritional status. The gait speed improvement observed in men warrants further investigation.