Long-term weight loss can reduce the risk of type 2 diabetes for people living with obesity and reduce complications for patients diagnosed with type 2 diabetes. We investigated whether a telehealth lifestyle-coaching program (Liva) leads to long-term (24 months) weight loss compared to usual care. In a randomized controlled trial, n = 340 participants living with obesity with or without type 2 diabetes were enrolled and randomized via an automated computer algorithm to an intervention group (n = 200) or to a control group (n = 140). The telehealth lifestyle-coaching program comprised of an initial one-hour face-to-face motivational interview followed by asynchronous telehealth coaching. The behavioural change techniques used were enabled by individual live monitoring. The primary outcome was a change in body weight from baseline to 24 months. Data were assessed for n = 136 participants (40%), n = 81 from the intervention group and n = 55 from the control group, who completed the 24-month follow-up. After 24 months mean body weight and body mass index were reduced significantly for completers in both groups, but almost twice as much was registered for those in the intervention group which was not significant between groups -4.4 (CI -6.1; -2.8) kg versus -2.5 (CI -3.9; -1.1) kg, P = 0.101. Haemoglobin A1c was significantly reduced in the intervention group -3.1 (CI -5.0; -1.2) mmol/mol, but not in the control group -0.2 (CI -2.4; -2.0) mmol/mol without a significant between group difference (P = 0.223). Low completion was partly due to coronavirus disease 2019. Telehealth lifestyle coaching improve long-term weight loss (> 24 months) for obese people with and without type 2 diabetes compared to usual care.