SummaryThe prevalence of depression in those with obesity is reported to be as high as double that in individuals of normal weight. There is potentially a bi‐directional relationship between obesity and depression. Some research has suggested that depression results in weight gain and obesity, and other studies have suggested that those with obesity are more likely to develop depression at a later stage. The aim of this study was to investigate the association of depression symptoms with weight change over a 12‐month study. Seventy participants undertook a 3‐month lifestyle (diet and exercise) weight loss intervention, and were followed up as part of a 12‐month study. Participants completed the Beck Depression Inventory‐II (BDI‐II) and had their body weight measured throughout the study. Baseline body mass index (BMI) of participants (mean ± standard deviation [SD]) was 31.1 ± 3.9 kg m⁻², body weight was 89.4 ± 16.1 kg, and age was 45.4 ± 11.1 years; 63% of the cohort were female. The mean weight change from baseline to 3 months was −5.2% (±SD 4.3%), and from baseline to 12 months was −4.2% (±SD 6.1%). There was a significant decrease in BDI‐II scores over the 12‐month study, and a 1‐unit decrease in BDI‐II score was associated with a further decrease in body weight of −0.4%. The current study indicated that weight loss was associated with improvements in mood for non‐clinically depressed individuals with obesity, and these improvements persisted during a period of 3–12 months of follow‐up.