So it wasn't your fault after all if that diet didn't work for you - a new study as now determined that the secret to losing weight is not about how well you can diet; it has actually got to do more with your genes.
Apparently, some women are genetically programmed to achieve more success than others when they follow a diet plan.
To reach the conclusion, Stanford University researchers took mouth swabs from more than 100 overweight women who had tried various diets.
Then they analysed the women's DNA for five genes linked to how the body uses fat and carbohydrate.
After analyses, researchers found that women following diets that matched their genotype, or genetic make-up, shed nearly a stone on average over a year - almost three times more than the other women, reports The Telegraph.
These women also saw their waistlines reduced by 2.6 inches on average, compared with 1.2 inches, the American Heart Association's annual conference heard.
Dr Christopher Gardner, of Stanford University, who led the study, said: "The differentiation in weight loss for individuals who followed a diet matched to their genotype versus one that was ot matched to their genotype is highly significant and represents an approach to weight loss that has not previously been reported in literature."