Effect of Intermittent Versus Continuous Energy Restriction on Compensatory Mechanisms Activated During Weight Reduction

Effect of Intermittent Versus Continuous Energy Restriction on Compensatory Mechanisms Activated During Weight Reduction

Effect of Intermittent Versus Continuous Energy Restriction on Compensatory Mechanisms Activated During Weight Reduction

Obesity has become a global epidemic with huge public health implications. Although clinical significant weight loss can be achieved by a combination of diet and behavioral modification, strong metabolic adaptations, with increased appetite and suppressed energy expenditure, are activated, which compromise weight loss maintenance and increase the risk of relapse. The aim of this project is to compare the effects of intermittent versus continuous energy restriction on the compensatory responses previously described using two low calory diets, with a similar macronutrient distribution. More specifically, this study will analyze, in the short-term, if an intermittent energy restricted diet is associated with less appetite and low reduction in energy expenditure when compared with a continuous energy restricted diet. This project can bring large practical benefits concerning the design of weight loss programs to minimize weight relapse.

The intermittent energy restricted group will undergo 3 nonconsecutive days of partial fasting per week. During the 3 days of partial fasting, participants will be asked to consume a very-low calorie diet (VLCD) providing 550kcal/day for women and 650kcal/day for men. The VLCD products provide 110kcal/pack and include a variety of shakes, smoothies and soups. For the feeding days a diet matching energy needs will be prescribed, using meal replacements (such as smoothies, soups and cereal bars) and conventional food. Drinking at least 2.5 liters of non-caloric liquids will be recommended.

The continuous energy restricted group will be prescribed a low calorie diet (LCD) with 33% energy restriction, using meal replacements (such as smoothies, soups and cereal bars) and conventional food. The diets' macronutrient composition of the two groups will be matched (50% carbohydrates, 20% protein and 30% fat).

Appetite-related hormones (active Ghrelin, PYY, GLP-1, CCK) will be measured in fasting and every 30 minutes up to 2,5 hours.

Inclusion Criteria: adult (18-50 years old) obese healthy volunteers (30<BMI<40 kg/m2) weight stable on the last three months (<2kg), not currently dieting to lose weight and with an inactive lifestyle Exclusion Criteria: history of endocrine/cardiovascular/pulmonary/kidney disease anaemia milk intolerance depression or other psychological disorders eating disorders drug or alcohol abuse within the last two years current medication known to affect appetite or induce weight loss a planned surgery during the study period participating in another research study

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