Skuteczność stopniowej i szybkiej utraty wagi (GoLow)

16-week rapid weight loss (RWL) program [8-week LED (<1000 kcal/day) - followed by an 8-week gradual increase in energy intake (4 weeks <1300 kcal/day and 4 weeks <1500 kcal/day)] followed by a 36-weight loss maintenance program.

16-week rapid weight loss (RWL) program (8-week low energy diet (LED) followed by 8-week gradual increased energy intake) and a subsequent 36-week weight-maintenance follow-up

16-week GWL-program (estimated total energy expenditure minus 800-1000 kcal/day) followed by a 36-weight loss maintenance program.

16-week gradual weight loss (GWL) program (moderate calorie restriction) and a subsequent 36-week weight-maintenance follow-up

Percent total body weight loss (%TBWL) at 12 months follow-up

Waist and hip circumference (cm)

Bioelectrical Impedance Analysis (BIA)

Dual-energy X-ray Absorptiometry (DXA) in selected participants

Total-cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides (mmol/l)

Systolic and diastolic blood pressure (mm/Hg)

HbA1c (mmol/mol)

CRP (mg/L)

Generic questionnaire: Short Form-36 Health Survey, SF36. Each item is scored on a 0 to 100 range so that the lowest and highest possible scores are 0 and 100, respectively. Scores for each of the 8 domains and summary scores for physical and mental health will be calculated

Obesity specific questionnaire: IWQOL-lite. The IWQOL-Lite is a 31-item measure of weight-related quality of life. There are five domain scores (Physical Function, Self-Esteem, Sexual Life, Public Distress and Work) and a total score. Scores for all domains and total score range from 0-100, with lower scores indicating greater impairment.

Weight-related Symptom Measure (WRSM). The validated obesity specific WRSM measures 20 symptoms commonly related to being overweight or obese, including foot problems, joint pain, sensitivity to cold, shortness of breath, etc. using two different sets of items. The first set assesses whether or not a patient is experiencing specific symptoms, and the second set rates the level of the distress of the symptoms with values from zero ("not at all") to six ("bothers a very great deal"). The first set creates an additive scale summing symptoms from 0-20, while the second forms a symptom distress scale ranging from 0-120.

Hospital Anxiety and Depression Scale (HADS). The validated generic HADS measures symptoms of anxiety and depression using 14 items scored from 0-3 It is decomposed into two domains measuring depression (HADS-D) and anxiety (HADS-A), both consisting of seven items yielding a score from 0-21.

The Three Factor Eating Questionnaire -R 21 (TFEQ-R21) measures eating behaviour and has been validated for use in individuals with obesity and will be used in the study. It consists of 21 items comprising three domain scores; (1) uncontrolled eating; assessing the tendency to lose control over eating when feeling hungry or when exposed to external stimuli, (2) cognitive restraint; assessing the conscious restriction of food intake to control body weight or body shape, and (3) emotional eating; assessing overeating related to negative mood states. The domain scores were transformed to 0-100 scales to facilitate comparison; a higher score indicates more uncontrolled, restraint, or emotional eating.

Percent total body weight loss (%TBWL) at 4 months follow-up

TBWL of ≥ 5%, ≥10% and ≥15% at 52-week follow-up