The study is a single site parallel randomized controlled study. The study will be assessing the effect of approximately 10% weight loss intervention vs a control group among healthy females/couples where the prospective mother is overweight or obese (BMI 27-45 kg/m\^2) and between 18-38 years. The investigators will recruit a total of 240 healthy females/couples who will be randomized 1:1 to either intervention or control, stratified according to maternal pre-pregnancy BMI. The overall objective is to test whether a comprehensive pre-conceptional parental weight loss intervention effectively reduces the risk of offspring overweight and adiposity and its complications compared to a control group. The investigators hypothesize that parental weight loss intervention, initiated before conception, will facilitate lower parental insulin resistance, inflammation, body weight and adiposity, incretin responses compared to usual care. For the offspring the investigators hypothesize that the intervention will reduce adverse pregnancy outcomes with a reduction in offspring neonatal adiposity, reduced risk of being born large for gestational age (LGA) and with lower BMI z-score at 18 months.