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Effect of weight change and lactation (the EVA-study)

The objective of the study is to investigate the effect of lactation and weight change on risk factors for cardiovascular disease among overweight postpartum women.

Newborn baby beeing breast fed

Illustration: Colourbox

About the project                                       

The objective of this project is to test whether breastfeeding leads to changes in risk markers for cardiovascular disease and diabetes beyond the effect of weight loss.

The participants are healthy women with a pre-pregnant BMI (body mass index) between 25-35 kg/m2 who are planning to breastfeed their child.

Two interventions will be tested:

Lactation promotion intervention, consisting of consultations during pregnancy and after delivery by an experienced lactation consultant. The intervention aims to facilitate breastfeeding according to the national guideline on infant nutrition.

Weight loss intervention, which involves participation in a 12 week weight loss program. The women join the intervention at 8-10 weeks after delivery. The goal is to lose 0.5 kg per week, as well as to achieve lasting changes in life style. 

Recruitment of participants will begin in January 2018 and is expected to be completed within two years. Participants will mainly be recruited from health clinics in Oslo and through social media.


Breastfeeding has a number of positive effects on health, for both mother and child. For the mother, lactation seems to protect against both cardiovascular disease and diabetes.

Overweight and obesity affects one out of three Norwegian women at the beginning of pregnancy. In addition, some women gain excessive weight during pregnancy, or retain pregnancy weight after delivery, which predisposes the women for overweight later in life.

Pregnancy involves several metabolic changes. For example, the blood levels of cholesterol and triglycerides increase gradually during gestation together with increasing insulin resistance. These changes are more pronounced among overweight women.  A “normalization” of the metabolism happens during the postpartum period, which is favorable considering future risk of cardiovascular disease and diabetes. Breastfeeding has been suggested to promote this process, resetting the metabolism back to pre-pregnant status. A weight reducing effect from lactation may be one potential mechanism.

Clinical trials performed by our research group in Sweden have shown that a weight reduction program of 12 weeks, aiming a weight loss of 0.5 kg per week, is safe and efficient for lactating women with overweight. In addition to weight loss, there is a positive effect on blood lipids and fasting insulin.

To separate the effect of lactation and weight reduction, we aim to allocate the participants into four groups, where they receive either breastfeeding promotion, weight loss program, both interventions, or no intervention. In addition, the women will be invited to participate in a sub study, which involves analyses of breastmilk and blood for environmental toxins.


  • The Research Council of Norway
  • The Dam foundation via Norwegian Women's Public Health Association
  • Throne Holst Foundation of Nutrition Research


  • Norwegian National Advisory Unit on Breastfeeding, Oslo University Hospital
  • Norwegian Institute of Public Health
  • University of Gothenburg, Sweden
  • Örebro County Council, Sweden
  • Cornell University, USA
Published Jan. 10, 2018 11:30 AM - Last modified Feb. 17, 2021 6:05 PM