This study evaluates effect of weight loss in a group of obese patients with gouty arthritis. The study is a randomised group trial where half the patients receive intensive weight loss in the form of meal replacement from Cambridge as well as supervision from a clinical dietician and the other half get usual care.

Background Gout is an increasingly common disorder characterised by elevated serum urate (SU) and by acute and chronic arthritis causing severe disability and pain. Long-term management of gout focuses on urate-lowering therapy (ULT), and keeping SU under its solubility threshold. When SU is kept under the threshold for solubility, the frequency of gout flares will decrease and the urate crystals dispositioned in the joints will dissolve. New therapeutic management of gout has in recent years emerged. However, despite the potential for effective treatment, gout management remains suboptimal.

there is some physiological evidence, although sparse, that weight loss in patients with gout reduces both SU and number of gout flares. Despite the scarcity of data regarding the effects of weight loss in gout, international guidelines recommend dietary intervention and weight loss as a core management strategy in patients with concomitant gout and obesity The aim with the current study is to address whether or not there is a difference in success rate in weight reduction, SU levels, and possible side-effects between the 2 approaches in the "short-term", by comparing a weight loss group to an ongoing no-treatment (usual care) group.

recruitment Participants will be recruited from the out-patient clinics at the Parker Institute, Bispebjerg and Frederiksberg Hospital and the Department of Rheumatology, Herlev-Gentofte Hospital, Denmark, through advertisements in newspapers and on the website of the Parker Institute. Additionally, local general practitioners will be informed about the possibility to assign patients to the project. All participants will be pre-screened via telephone using a series of standard questions about eligibility according to criteria of inclusion and exclusion. This study aims at being as pragmatic and inclusive as possible with few exclusion criteria

Interventions All the participants who sign informed consent will be randomly assigned to either 16 (8+8) weeks of low-energy diet (LED; 3.4 MJ/day; i.e., the Intensive Diet [ID] group) OR a corresponding 16-week conventional hypo-energetic, high protein diet (app. 5 MJ/day) defined as a control group (i.e., conventional diet [CD] group).

Intensive Diet (ID) Group: The first phase of the study consists of an 8-week weight reduction programme where the participants initiate an LED diet-only, with 3.4 MJ/day (810 kcal per day) in a supervised dietary programme (products provided by The Cambridge Weight Plan). They will be given nutritional and dietetic instructions by an experienced dietitian in sessions of 1-2 h weekly.

The second phase (ID Group) of the study (week 8-16), will consist of an 8 weeks' fixed energy diet programme using 5 MJ/day (1,200 kcal per day) incorporating two diet products daily. The principles of the diet will be in line with the current guidelines for healthy eating issued by the Danish National Board of Health, i.e. low-fat, low-sugar and high-fibre.

Conventional Diet (CD) Group: The programme will consist of a presentation by the same dietitian as for the ID group, who will provide nutritional advice in a 2 h session at baseline (week 0), and in week 8. At these sessions the dietitian will recommend eating ordinary foods in amounts which will provide the patients with approximately 5 MJ/day (1,200 kcal per day). The follow-up meeting at week 16 will not influence the outcome. Thus, during the 16 week trial, the CD group will attend three sessions altogether with a total of approximately 4h of instruction.

Inclusion Criteria:

• a diagnosis of gouty arthritis per expert opinion and the ACR/EULAR 2015 criteria for gout.
• have had at least one self-reported flare in the last 12 months
• BMI >30kg/m2
• >18 years of age

Exclusion Criteria:

• pregnant
• hisotry or suspicion of drug abuse within the past 5 years
• Active muscle disease, cancer, previous kidney disease, and/or fatty liver
• An estimated creatinine clearance <30 mL/min calculated by the Cockcroft-Gault formula using ideal body weight.
• An investigational therapy within 8 weeks or 5 half-lives (whichever is longer) prior to the screening visit.
• Any other medical or psychological condition which, in the opinion of the investigator and/or medical monitor, might create undue risk to the patient or interfere with the patient's ability to comply with the protocol requirements, or to complete the study.