Dieticians call for action on overweight mothers-to-be

Medical Tribune July 2009 P16

David Brill

Overweight women should receive nutrition counseling before, during and after pregnancy, leading US dietitians have advised.

With the global obesity epidemic showing no signs of slowdown, the health of mothers and babies alike is at risk unless eating habits improve, cautions a recent joint statement from the American Dietetic Association (ADA) and the American Society of Nutrition (ASN).

Studies show that obese mothers are more likely to experience preeclampsia, gestational diabetes mellitus (GDM), gestational hypertension, postpartum anemia and cesarean delivery than women of normal weight. Their offspring, meanwhile, face an increased risk of birth defects, fetal macrosomia, childhood obesity and even perinatal death.

Ms. Ximena Jimenez, a consultant dietitian and national ADA spokesperson, said that healthcare professionals across the spectrum should work together to promote healthy eating and physical activity in women who are pregnant or planning to conceive. Physicians, for example, can play “a big role” in reinforcing the advice given by dietitians and other specialists, she said.

“A lot of the time it takes more than one type of counseling to get these women to change their lifestyle. I would encourage any healthcare professional to encourage these women to seek nutrition counseling,” she said.

“The principles are that you want them to increase whole grains and decrease refined carbohydrates like cakes, pastries and white breads. We also want them to replace saturated fat with healthy fats like omega-3 fats or fats from olive oil, canola oil or avocado, and also to increase their intake of fruits and vegetables. We also want them to be physically active,” she added.

Some 52 percent of women aged 20 to 39 in the US are overweight or obese (BMI 25 or above), according to data from the National Health and Nutrition Examination Survey of 2003-2004. Twenty-nine percent are obese (BMI 30 or above) and 8 percent are extremely obese (BMI 40 or above). Among adolescent girls aged 12 to 19, almost 32 percent are overweight or at risk of being overweight. [JAMA 2006 Apr 5;295(13):1549-55]

Despite the scale of the task, Jimenez remains optimistic that overweight women can be successfully counseled.

“I think it’s a very realistic target. There has to be promotion of healthy eating among women,” she said. “Imagine the benefits. As a society we are all going to benefit because we are going to have healthy women and healthy children.”

Jimenez highlighted studies showing the success of dietary interventions in overweight mothers, such as the Nurses’ Health Study, which found that risk of GDM was approximately halved by following a low-glycemic, high-cereal fiber diet. [Diabetes Care 2006 Oct;29(10):2223-30] The risk of preeclampsia can also be halved by taking calcium supplements, a meta-analysis of 12 studies shows. [Cochrane Database Syst Rev 2006 Jul 19;3:CD001059]

The new ADA / ASN position statement also reviews the literature on the prevalence of various pregnancy outcomes for overweight mothers and their babies. [J Am Diet Assoc 2009 May;109(5):918-27]

The risk of developing GDM, for example, is reported to double in overweight women, and increase over eightfold in the extremely obese. [Diabetes Care 2007 Aug;30(8):2070-6] Preeclampsia risk is around three times higher in pregnant women who are obese than those of normal weight. [Obstet Gynecol 2007 Feb;109:419-33]

The offspring of obese mothers are around twice as likely to have neural tube defects such as spina bifida, according to the US National Birth Defects Prevention Study. [Arch Pediatr Adolesc Med 2007 Aug;161(8):745-50] Oral clefts, hydrocephaly and cardiac abnormalities were also found to be more common in these infants than those born to normal-weight mothers.

Picking and choosing: No way to lose weight

Medical Tribune May 2009 P13
David Brill

Weight loss diets which promote one particular food group may not be the best way to shed the kilos, a recent study suggests.

In one of the longest trials of its kind, US researchers found that there was ultimately little difference in weight loss whether diets emphasized carbohydrates, protein or fat.

Nor did waist circumferences differ significantly after 2 years of following the diets, the study of 811 overweight adults showed.

"This is important information for physicians, dieticians and adults, who should focus weight loss approaches on reducing calorie intake," said lead author Professor Frank Sacks, Harvard School of Public Health, US.

Participants were randomized to one of four diets. The compositions varied, but all targeted a 750 kcal decrease in daily intake. [N Engl J Med 2009;360(9):859-73]

Weight loss peaked at 6 months – when participants had lost an average of 6 kg, or 7 percent of their initial weight. Weight regain began after 12 months: those who completed the study had lost an average of 4 kg at its conclusion.

The researchers also found that people who attended the most group counseling sessions lost the most weight – an average of 0.2 kg per weekly session.

"These findings suggest that continued contact with participants to help them achieve their goals may be more important than the macronutrient composition of their diets," said Sacks.

Singapore’s Health Promotion Board (HPB) welcomed the study as an informative, but not definitive, addition to the literature.

“The study was limited in that the differences in the macronutrient content of the different diets was not as substantial as originally planned, hence the resultant diets did not fully replicate the macronutrient distribution of popular ‘low-carb’ or low-fat diets,” said Mr. Benjamin Lee, manager and nutritionist, adult health division, HPB.

The HPB advocates a holistic approach to weight loss including exercise and stress management, added Lee. Specific dietary recommendations are to focus on calorie reduction while maintaining a diet which covers four food groups: rice and alternatives, fruit, vegetables, and meat and alternatives (including dairy foods).

Ms. Jamie Liow, a nutritionist and member of the Singapore Nutrition and Dietetics Association, said that carbohydrate intake is typically a concern among Asians who diet.

“Most would either have a low-carbohydrate, high-protein diet, or no carbohydrates at all. Crash dieting seems to be popular among younger girls as well,” she said.

Liow also emphasized the importance of getting nutrients from “a whole spectrum of foods,” adding that doctors should refer their patients to dieticians for specific advice on the best way to lose weight.

The four diets tested by Sacks et al. comprised: 20 percent fat, 15 percent protein and 65 percent carbohydrate; 20 percent fat, 25 percent protein and 55 percent carbohydrate; 40 percent fat, 15 percent protein and 45 percent carbohydrate; or 40 percent fat, 25 percent protein and 35 percent carbohydrate.

The lowest-fat and the highest-carbohydrate diets brought about the greatest reduction in LDL cholesterol levels, whereas the lowest-carbohydrate diet yielded the biggest increase in HDL cholesterol. Triglyceride levels dropped similarly for all diets.

Dieters were also encouraged to exercise for 90 minutes per week, and received weekly group counseling sessions and 8-weekly individual sessions.

Despite this intensive encouragement, dieters did not meet their nutrient intake targets when questioned at 6 months and 2 years. This appears to be a common problem in weight-loss trials, say the authors, noting that many previous studies have also found that adherence declines after a few months.

Lifestyle program boosts diabetes control in overweight Chinese

Medical Tribune March 2009 SFV
David Brill

An integrated lifestyle intervention program, including dietary supplements and meal replacements, can help overweight Chinese diabetics lose weight and improve glycemic control, a new study has shown.

Patients who followed the program for 24 weeks lost an average of 2.7 kg and saw their HbA1c drop by 0.8 percent compared to baseline (P<0.001).>

Such were the benefits of the intervention that 15 of the 100 type 2 diabetics who followed it had had their diabetes medication dosages reduced by the end of the trial, while a further seven stopped taking them altogether.

The results of the study, led by Dr. Jianqin Sun of Fudan University, Shanghai, were announced at a recent Singapore press conference and published in the Asia Pacific Journal of Clinical Nutrition. [2008; 17(3):514-24]

The intervention program included diabetes education, nutritional counseling, meal replacement with dietary supplements, and weekly progress reports with a physician and a dietician. It was compared in a randomized prospective trial against a simpler intervention comprising only education on diet and physical activity. Fifty patients were included in this reference group.

Professor William Garvey, a US diabetes expert who commented on the study, described the reduction in HbA1c as “very impressive” given that the intervention patients were already well-controlled, with an average HbA1c of 7.1 percent at baseline. He also noted that the potential to reduce or stop medications provides a good incentive for diabetic patients to lose weight, but stressed that these adjustments should only be made following proper consultation with a physician.

Dr. Kevin Tan, vice-president of the Diabetic Society of Singapore, said that the study demonstrates the viability of meal supplements as a therapy for diabetes, adding that this option should be explored for all patients who are overweight.

“Meal supplements or replacements have not been talked about much so a lot of doctors don’t think about them, but they do play a part in diabetes management in terms of helping to reduce calorie intake and helping patients to lose weight. If GPs realize that this can be part of their usual holistic diabetes care, along with the medications, exercise and weight control, then I think it will help to improve sugar control in their diabetic patients,” he said.

Participants in the study were all type 2 diabetics aged 18 to 70 with a BMI of 23 kg/m2 or above. The lifestyle intervention also significantly improved blood pressure (BP), with patients in this group recording average reductions of 7.5 mmHg for systolic BP and 3.4 mmHg for diastolic BP, at 24 weeks as compared to baseline. These reductions were significantly greater for the intervention group compared to the reference group.

The waist-to-hip ratio was also reduced among patients in the intervention group compared to those in the reference group.

“Dietary supplements are not the magic answer for everybody but they can be helpful in many patients,” said Garvey, who is based at the University of Alabama at Birmingham, US.

“If you have a patient who needs to lose weight and you feel that they need more structure in terms of their dietary plan – less guesswork and more clear-cut guidance in terms of what the diet will be from day to day – a meal replacement is a really good tool to use,” he said.

Garvey acknowledged that the short duration of the trial makes it hard to assess the long-term sustainability of the intervention, but added that the structured nature of the program teaches important behavioral modification skills which continue to be applicable beyond the trial setting.

The burden of type 2 diabetes in China is increasing rapidly, according to the study authors, who note that the prevalence among large city residents rose from 4.6 percent in 1995 to 6.4 percent in 2002. In Singapore the burden could be even higher, with data from the 2004 National Health Survey suggesting a diabetes prevalence of 8.2 percent among residents aged 18 to 69.

The trial by Sun et al. was funded by Abbott Laboratories, which manufactures the dietary supplement used in the study.

Liver fat a predictor of ‘metabolically benign obesity’

Medical Tribune December 2008 P6
David Brill

Measuring the distribution of fat in the liver could help identify obese patients who are most in need of treatment, a new study suggests.

The researchers characterized a subset of people with "metabolically benign obesity," who, despite their increased weight, do not seem to be at high risk of diabetes and atherosclerosis.

These patients, comprising around a quarter of the obese subjects in the study, had comparable insulin sensitivity and carotid intima media thickness to normal-weight people.

Ectopic fat in the liver was the strongest predictor of this phenotype and could therefore be used for risk stratification of obese patients, according to lead author Professor Norbert Stefan.

"Clinicians are seeing so many obese people now that they really need to try and focus their resources on those who need treatment earliest. By identifying those who are not in such high need they can put them on more moderate treatment," said Stefan, who heads a research team at the University of Tübingen in Germany.

MRI scans showed that the benign obese group had on average 54 percent less fat accumulation in the liver than insulin-resistant obese subjects (4.3 percent vs. 9.5 percent). The presence of ectopic fat in skeletal muscle was also a determinant of insulin sensitivity.

By measuring visceral adiposity – a known predictor of type 2 diabetes and cardiovascular risk – researchers were able to differentiate between insulin-sensitive and insulin-resistant subjects in the normal-weight and overweight groups. However, visceral adiposity was a weak predictor among the obese.

Doctors should assess patients for all the classical risk factors for cardiovascular disease and diabetes and then consider using MRI to measure liver fat in those deemed to be at high risk, Stefan said. Liver enzymes and ultrasound can also help to provide an assessment, he added.

The study, published in The Archives of Internal Medicine, comprised 314 white subjects with an average age of 45. [2008 Aug 11;168:1609-16]

Stefan stressed the importance of putting out the right public health message regarding the study’s findings.

"This is the start – it identified an important new target but we still need to tell the metabolically healthy obese people that they can’t lean back and say ‘okay that’s it, I’m not at risk.’

"Every obese person needs treatment, even the metabolically benign, because we’re not sure whether the endpoints are that they have a lower risk of dying or developing disease," he said.

A second study, published in the same edition of the journal, looked at the association between cardiometabolic abnormalities and obesity in a cross-sectional sample of 5,440 US adults. The researchers found that 31.7 percent of obese people were metabolically healthy, while 23.5 percent of normal-weight people were in fact metabolically unhealthy. [Arch Intern Med 2008 Aug 11;168(15):1617-24]

Stefan’s research, meanwhile, is now looking at the parameters that regulate the accumulation of liver fat. A larger 2-year study involving 400 people is currently ongoing and is expected to be completed early next year, he said.

Unhealthy diet raises heart attack risk by 35 percent

Medical Tribune December 2008 SFXIV

David Brill

Eating a diet high in salt and fried foods can increase the risk of acute myocardial infarction (AMI) by as much as 35 percent, according to a large-scale study conducted across 52 countries worldwide.

The analysis of 5,761 AMI cases and 10,646 controls from the INTERHEART study also highlighted the benefits of eating fruit and vegetables – a dietary pattern that reduced AMI risk by 30 percent.

The chairman of the Singapore Heart Foundation, Dr. Terrance Chua, said that the findings should serve as a warning to Singaporeans, who are increasingly moving towards the unhealthy diet described in the paper.

"This is a message that all the various health promotion bodies in Singapore have been advocating all along, but knowledge is one thing and actual practice is another. Changing behavior is a real challenge," he said.

Chua hailed the global scale of the study as "very significant" since most previous research in this area had been limited to Western countries.

"This allows us to extend those results to different populations and different ethnic groups," he said.

"In a way it’s confirmed our understanding that high fat, salty snacks and dairy products are associated with an increased risk. Unfortunately that’s the diet that everyone in the world is tending to develop because it’s seen as the diet of successful societies."

The National Nutrition Survey of 2004 showed that although Singaporeans are eating more fruit and vegetables they are also consuming more fat, an increasingly high proportion of which is saturated.

Dr. Seow Swee Chong, a consultant cardiologist at National University Hospital, agreed that the findings from the INTERHEART study are a concern for Singaporeans but was more cautious in his appraisal of the research.

"This study is hypothesis-generating but not conclusive," he said, adding that the exact extent to which diet influences risk remains unclear since there are several limitations to the paper.

"The type of diet is undoubtedly influenced by the region that the study subject is from and also his ethnicity. Thus the findings may reflect more of a difference in propensity towards AMI due to genetic, racial or geographical factors rather than the diet. Indeed, there was a significant interaction between diet and region in the study," he said.

Participants in the case-control study were enrolled at 262 centers between February 1999 and March 2003. Dietary patterns were assessed using a 19-item food frequency questionnaire. [Circulation 2008 Nov 4;118(19):1929-37]

The international research team, led by McMaster University and Hamilton Health Sciences, Ontario, Canada, divided diet into three types: ‘prudent’ – high in fruit and vegetables, ‘Western’ – rich in fats, meat and salt, and ‘Oriental’ – high in tofu, soy and other sauces.

The adjusted odds ratios for AMI were 1.35 and 0.70 for those in the highest quartile
of adherence to the Western and prudent diets, respectively, compared to those in the lowest quartile (P for trend <0.001).>

Chua and Seow, however, both expressed reservations about the arbitrary classification system employed by the authors, preferring instead to focus on the components of the diet.

"It’s important not to be confused by the labeling and think that a Western diet is unsafe but it’s fine to eat nasi lemak and chicken rice," said Chua, noting that Asian food often contains just as much fat as Western food.