Healthy Eating Beats Exercise to Limit Weight Gain in Pregnancy

Veronica Hackethal, MD

July 06, 2015

A small pilot study in Europe has suggested that a lifestyle intervention aimed at healthy eating reduces gestational weight gain (GWG), fasting glucose, and 2-hour insulin concentrations among obese pregnant women more than increased physical activity alone. The study was published online June 25 in Diabetes Care.

"A healthy-eating intervention for obese pregnant women is to be preferred to a physical-activity intervention based on this pilot study for limiting gestational weight gain," commented senior author Mireille van Poppel, PhD, of the VU University Medical Center in Amsterdam, the Netherlands.

Obesity and excess weight gain during pregnancy have been linked to increased risk for pregnancy and birth complications. Research, though, has shown mixed results about whether lifestyle interventions make much difference in reducing excess gestational weight gain and gestational diabetes mellitus (GDM).

This pilot study looked at risk for GDM, not GDM itself, as it wasn't powered to find a difference in the latter — still, the women in this study had a "very high" incidence of developing gestational diabetes, at around 32%, Dr van Poppel pointed out.

And the study sets the stage for a much larger multicenter European randomized clinical trial — the Vitamin D and Lifestyle Intervention for GDM Prevention (DALI), which, unlike this pilot study, will also examine the contentious role of vitamin D supplementation in pregnancy.

Healthy Eating Reduces Weight Gain, a "Surprising Finding."

The randomized trial included 150 pregnant women with a body mass index (BMI) of 29 kg/m2 or more who were enrolled from nine European countries. Women were screened for GDM using a 75-g oral glucose tolerance test before 20 weeks' gestation.

Those who did not have GDM according to WHO 2013 criteria (fasting plasma glucose >5.1 mmol/L) were included in the study and randomized to healthy eating alone, physical activity alone, or healthy eating plus physical activity.

Women received coaching on healthy eating, physical activity, or both using the principles of motivational interviewing during five face-to-face and four optional telephone calls. Coaches had received standardized training and an intervention tool kit.

The primary outcomes were maternal weight gain (defined as the weight change from baseline measurement to the last measurement at 35–37 weeks of gestation), fasting glucose, and insulin sensitivity as derived from the homeostasis model assessment (HOMA) at 35 to 37 weeks.

From baseline to 35 to 37 weeks, women gained an average of 8.6 kg, although 20% were able to reach the gestational weight gain goal of less than 5 kg.

At 24 to 28 weeks, women randomized to healthy eating experienced less gestational weight gain compared with women randomized to physical activity alone (adjusted difference -2.6 kg, P = .03). Between baseline and 35 to 37 weeks, women randomized to healthy eating continued to have significantly less gestational weight gain compared with the physical-activity group (adjusted difference -1.6 kg, P = .02).

By 35 to 37 weeks, women randomized to healthy eating also had significantly lower fasting glucose and 2-hour insulin, compared with women in the physical-activity group (adjusted difference -0.3 mmol/L, P = .01; and adjusted difference -0.4, P = .04, respectively).

Dr van Poppel and colleagues say there was no expectation that the study would be large enough to show a difference in the primary outcomes comparing different interventions, so the significant differences in gestational weight gain, fasting glucose, and 2-hour insulin levels, albeit trivial, between the healthy-eating and physical-activity groups were "therefore surprising."

These pilot findings are promising and support the use of early healthy-eating interventions in obese pregnant women, they add.

Combining Advice May Dilute the Message

Moreover, the healthy-eating/physical-activity group showed no significant differences in gestational weight gain, fasting glucose, 2-hour insulin, and percent GDM compared with the other two groups.

"More is not always better. Combining counseling on healthy eating and physical activity seems less or equally effective compared with healthy eating alone," Dr van Poppel said.

Combining healthy eating plus physical activity might "dilute the message" or require too much change that could ultimately undermine motivation, the authors point out.

Because of its small size, the study could not assess differences in obstetric outcomes or in GDM incidence. Many past studies have been similarly underpowered and could not detect differences in outcomes like GDM, explained Dr van Poppel.

One key issue is that lifestyle interventions, in general, have not had much of an impact on metabolic outcomes.

"Why our study was successful in changing metabolic outcomes and others were not is not so easy to explain but might be related to the type of intervention," which will be further assessed in the near future in the full DALI trial, she added.

And whether or not the study's results will translate into improved perinatal outcomes also remains to be seen.

"Our pilot study was not designed to evaluate effects on fetal outcomes, such as birth weight or being large-for-gestational age. Results regarding fetal and neonatal outcomes will emerge from the full study," she explained.

Results of the larger DALI trial are due to come out later this year.

This project has received funding from the European Community's 7th Framework Programme. In the Netherlands, additional funding was provided by the Netherlands Organization for Health Research and Development; in the United Kingdom, by the NIHR Clinical Research Network Eastern; and in Spain, by CAIBER. Dr van Poppel reports no relevant financial relationships. Disclosures for the coauthors are listed in the article.

Diabetes Care. Published online June 25, 2015. Abstract

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