Weight loss before pregnancy to reduce childhood obesity risk

Maternal inclusion Criteria:

* Maternal pre-pregnancy BMI 27.0-44.9 kg/m\^2
* Maternal age range 18-38 years
* Connected to Aarhus University Hospital as place of birth
* Pregnant

Paternal Inclusion Criteria:

* Paternal pre-pregnancy BMI 18.5-44.9 kg/m\^2
* Paternal age range 18-55 years

Parental Inclusion Criteria:

* Couples (male and female)
* Planning pregnancy within 3 years
* Provided voluntary informed consent
* Danish or English speaking
* Intention to permit the planned offspring to participate in the follow-up study
* Able to store biological samples from the offspring at home in the freezer in a box given by the study personnel

Parental Exclusion Criteria:

* Diabetes mellitus (Type 1 or 2)
* Previous or present eating disorder
* Allergy towards ingredients in the very low calorie diet products
* Severe heart, liver or kidney disease
* Conception by in vitro fertilization
* Any medical condition or concomitant medication as judged by the medical responsible
* Adherence to vegan diets or other diets interfering with the dietary guidelines in the study
* Participation in other clinical trial that can affect the results of the current study
* Engagement in elite sports or similar strenuous exercise ≥5 h/week at inclusion
* Blood donation or transfusion within the past month before screening
* Blood donation during the study
* Inability or unwillingness to follow the study protocol and instructions given by the study personnel

A detailed description of the exclusion criteria is given below:

Medical conditions as known by the participant:

* Diabetes mellitus (type 1 and 2)
* History or diagnosis of eating disorder (e.g. restrained eating, disinhibition, emotional eating)
* Any significant medical condition as assessed by the investigator (e.g. dysregulated thyroid disease or reproductive diseases)
* Any significant psychiatric disorder (i.e. schizophrenia, bipolar disease or depression) as assessed by the investigator
* Severe chronic heart, liver and kidney disease
* Polycystic ovary syndrome with irregular cycle

Medication:

* Current use of medication or use within the previous three months with a potential to affect body weight or pregnancy as judged by the investigator (e.g. systemic corticoids)

Personal/other:

* Severe food allergies, food intolerances or dislike expected to interfere with the study, including allergy towards ingredients in the VLCD products
* Engagement in elite sports or similar strenuous exercise ≥5 h/week
* Blood donation or transfusion within the past month before screening
* Planned blood donation for other purpose than this study during participation
* Alcohol abuse, as judged by the investigator, within the previous 12 months
* Drug abuse, as judged by the investigator, within the previous 12 months
* Psychological or behavioral problems which, in the judgement of the investigator, would lead to difficulty in complying with the study protocol
* Participation in other clinical trials within the past three months or intention to do so during the study, which are judged by the investigator to affect the present study
* Unable to consume the interventional product for religious reasons, swallowing disorders, other physiological reasons or any other reasons for not being able to follow the recommended diet
* Inability or unwillingness to give written informed consent or communicate with study personnel
* Inability or unwillingness to follow the study protocol and instructions given by the study personnel
* Illiteracy or inadequate understanding of Danish or English language.
* Any other condition that judged by the investigator may interfere with the adherence to the study protocol