Obesity and osteoarthritis (OA) co-exist in an increasing part of the population.

The two diseases intertwine in several ways. The evolution in the population shows a tendency towards deterioration of both by increasing general age and weight. The two diseases share pathogenetic features and the development of one disease increases the risk of the other and may be the onset of a vicious circle.

There is a link between treatments of these two diseases as well. There is now solid (gold) evidence that by treating effectively the obesity of patients with co-occurring OA, the functional status is dramatically ameliorated; the short-term results are equal to that of a joint replacement. The long-term efficacy of a weight loss remains to be shown. OA is definitely one of many diseases in which obesity must be taken seriously into account when planning a correct treatment of patients. This trial is an extension of the former CAROT trial NCT00655941. The participants of this trial are recruited for a prolongation of the dietary intervention consisting of a group therapy with low-energy diet in a randomized, two group (each n = 75 patients) study of maintenance of weight loss by continuing with supplementary either 3 x 5 weeks dietary supplements only or once-daily supplement. The hypothesis is that maintenance of the already induced weight loss is most efficiently ensured by the once-daily program.

Any patient with osteoarthritis (OA) of the knee was invited to participate in the preceding trial. Eligible for this study will be patients, who have completed the one-year phase 2 of the CAROT. Exclusion criteria are planned knee alloplasty of both knees.

Inclusion Criteria:

Former participant in the CAROT study ( NCT00655941 )

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Exclusion Criteria:

Bilateral knee alloplasty -