Low-carb ketogenic diets have become extremely popular because of large weight loss in the short-term. Yet their potential benefits in preventing long-term weight regain have not been assessed in large scale studies.

The aim of this study is to determine the effect of a low-carbohydrate (CHO) ketogenic diet, compared with an isocaloric balanced diet, on the maintenance of weight loss. The secondary aim is to investigate the impact of both diets on appetite. Adults with obesity (30\

Inclusion Criteria:

• weight stable over the last three months (<2 kg)
• not currently dieting to lose weight
• inactive lifestyle (less than 150 min of physical activity weekly.
• Given that some of the variables of interest have been shown to be affected by the phase of menstrual cycle in normally ovulating women, namely appetite and resting metabolic rate, only women taking oral contraceptives, with regular menstrual cycles or post-menopausal will be included in the study

Exclusion Criteria:

• pregnancy
• breast-feeding
• drug or alcohol abuse within the last two years
• clinically significant illness including diabetes, gastrointestinal (particularly cholelithiasis), kidney (GFR <60) or liver disease, osteoporosis (T-score <-2.5) and osteopenia (T-score <-1.5)
• treatment with antiosteoporotic drug
• depression or other psychological disorders
• eating disorders
• milk intolerance
• current medication known to affect appetite/metabolism or induce weight loss.
• a planned surgery during the study period
• participating in another research study