The burden of overweight and obesity has dramatically increased during the last decades. High carbohydrate intake, particularly refined carbohydrates, probably increase the risk of obesity, type 2 diabetes, and metabolic syndrome. There is evidence that energy-restricted low-carbohydrate diets show greater weight loss and better improvement of cardiovascular risk markers compared to energy-restricted low-fat diets. Beside macronutrient relations, efficacy of weight loss programs depends on care and control. The investigators aim to investigate whether or not a carbohydrate-restricted telemedically guided weight loss program results in a more pronounced weight loss and influences metabolic risk markers more beneficial than a fat-restricted diet.

see brief summary.

Inclusion Criteria:

• age 18-70 years
• body mass index > 27 kg/m2

Exclusion Criteria:

• history of cardiovascular symptomatology
• cholelithiasis
• urolithiasis
• insulin dependent diabetes
• pacemaker implantation
• pregnancy
• lactation
• vegetarianism