impact of cognitive dietary restraint on perceived stress, appetite sensations, food cravings during energy restriction

Conditions: Overweight

Summary: the purpose of this study is to measure the effects of a reduced-calorie low energy density diet with and without increased cognitive dietary restraint (cdr) on stress (biological markers and perceived stress), eating behaviours, appetite sensations, anthropometric variables and women's attitude toward their children's eating behaviours in premenopausal overweight/obese women in both the short term (immediately after the end of the 4-week intervention) and longer term (3 months after the end of the intervention). the investigators hypothesize that cortisol concentrations are higher, appetite sensations are increased (i.e. increased global appetite score) and food cravings are more prevalent in women of the energy-restriction-plus-cdr group than in women of the energy-restriction-without-cdr group after the 4-week intervention. they also hypothesize that perceived stress is higher and food cravings are more prevalent in women of the energy-restriction-plus-cdr group than in women of the energy-restriction-without-cdr group at 3-month post intervention. they hypothesize that no significant difference in body weight changes is observed between the two groups and that maternal restriction of their child's eating is higher in the energy-restriction-plus-cdr group than in the energy-restriction-without-cdr group both after the 4-week intervention and at the 3-month follow-up.

it is clear that a large proportion of individuals regain weight following dietary weight loss interventions most likely because of homeostatic and non-homeostatic factors favouring a return to initial energy status. however, studies performed to date have documented these effects in the context of interventions favouring both energy restriction and cdr. thus, the difference between a state of energy restriction alone and a state of energy restriction combined to cdr on factors regulating energy balance is not known. in order to study this important question appropriately, we need to create a condition of energy restriction without increasing cdr, which can only be achieved with a satiating diet (i.e. well-balanced low energy density diet). this is easier to create in the context of a controlled intervention in which all foods and drinks are provided. we propose to create, in a controlled context, an energy restriction for which subjects will be blinded i.e. they will consume less energy than their energy needs without knowing that they are restrained. such a design will permit to document for the first time the independent effects of cdr in the context of a reduced calorie diet on factors associated with the regulation of energy balance. the proposed study will also allow exploring the impact of increasing cdr on women's attitude toward their children's eating behaviours. taken all together, results arising from the proposed study will better position the relevance of developing weight loss approaches not focusing on cdr to favour healthy weight management for women and their family. data will be collected before and after the 4-week intervention, as well as 3 months after the end of the intervention. in order to appropriately test our hypotheses, we cannot state the real purpose of the study in the informed consent form and women will be told that it is a study about the impact of diet on blood pressure. however, at the end of the study, women will be debriefed and will sign a second informed consent form in which the true purpose of the study will be explained.

Eligibility criteria:
inclusion criteria: * premenopausal women (age between 20 to 50 years) from de quebec city metropolitan area * have at least one child (2 to 19 years) living at home * body mass index between 25 and 45 kg/m2 * stable body weight (+/- 2,5 kg) for at least 3 months before the beginning of the study exclusion criteria: * women with endocrine disorders, cardiovascular events and type 2 diabetes * women with medication that could affect dependent variables measured (namely medication affecting appetite) * smokers * women with food allergies or food aversion that could impede compliance to the diet * pregnant and lactating women * women with psychiatric disorders or eating disorders (e.g. bulimia)

Keywords: women caloric restriction cognitive dietary restraint eating behaviours food habits appetite sensations stress weight management