Dr Deirdre Tobais from Harvard Medical School in Boston, USA and her colleagues did a systematic review and meta-analysis of all randomised trials comparing the effectiveness of low-fat diets to other diets - including no diet - to see which resulted in long-term weight loss in adults.
Long term weight loss is viewed to keeping the weight off for at least 1 year.
They published the results in the The Lancet Diabetes & Endocrinology journal on 29 October 2015.
They took into account the intensity of the diets, which ranged from just pamphlets or instructions at the beginning of the programme to intensive multi-component programmes including counselling sessions, meetings with dietitians, food diaries and cooking lessons.
The meta-analysis, which involved 53 studies and more than 68 000 adults, found that low-fat diets do not lead to greater weight loss in the long term compared to higher-fat diets (eg, low-carbohydrate of Mediterranean diets) of similar intensity.
Those on low-carbohydrate diets lost an average 2.5lb (1.15kg) more than those on low-fat diets over 12 months, it showed.
The low-fat diets only led to greater weight loss when compared to people who didn't diet at all. And showed people lost more weight on low-carbohydrate diets than on low-fat diets.
Dr Tobias said that
According to Dr Tobias, the science does not support low-fat diets as the optimal long-term weight loss strategy and that for any diet to work, long-term adherence is critical.