Can MSG Cause Obesity?

Monosodium glutamate (MSG) is a food ingredient that is used to enhance flavor and palatability. It is the glutamate—the amino acid part—of the MSG molecule that does the job in this respect. MSG (and other sources of glutamate) can be found in a wide range of processed foods with the blessing of our governments and food agencies.

However, there has been lingering concern that glutamate might have some adverse effects on health, paralleling the effects of the artificial sweetener aspartame.One concern about aspartame has been that, despite being virtually devoid of calories, it might be contributing to the burden of overweight and obesity. It seems that aspartame can stimulate appetite.Some have leveled a charge that MSG may promote weight gain on the basis of experiments that showing it has this unwanted side effect in animals. However, until recently, the relationship between MSG consumption and weight gain had not been assessed in humans.That changed on the publication of a study this month in the journal Obesity [1].

The study, conducted in China, assessed the relationship between MSG consumption and body mass index (BMI) in 752 men and women aged 40 to 59. The researchers divided the participants in this study into three bands, according to MSG consumption. Compared to those in the lowest consumption band, those in the highest were found to be 2.75 times more likely to have a BMI of more than 25.This link between MSG consumption and increased body weight may have many explanations. The two obvious ones are that MSG somehow led individuals to consume more food or be less active. However, in this study, the authors accounted for these potential factors, which means that the link between MSG consumption and increased body weight appears to be independent of these factors.

The suggestion here is that MSG, the glutamate part, may have one or more metabolic effects in the body that might predispose consumers to weight gain. As it happens, administering MSG to animals has been shown to induce various changes that promote fat accumulation, including suppression of fat breakdown (lipolysis) [2]. The free, full-text version of this study is linked to below, which details other effects of MSG that might affect body weight in the long term.What is required now is for more work to be done to assess what effects MSG might have on human physiology that might cause weight gain. If one of the most commonly used food additives does indeed have the potential to cause weight gain, then it’s only right that we should know.

References:1. He K, et al. Association of Monosodium Glutamate Intake With Overweight in Chinese Adults: The INTERMAP Study. Obesity 2008; 16(8): 1875–18802. Dolnikoff M, et al. Decreased lipolysis and enhanced glycerol and glucose utilization by adipose tissue prior to development of obesity in monosodium glutamate (MSG) treated-rats. International Journal of Obesity Related Metabolic Disorders 2001; 25(3): 426–33

Dr. John Briffa is a London-based physician and author with an interest in nutrition and natural medicine. Dr. Briffa's Web site

Last UpdatedOct 23, 2008

Breast-Feeding Helps Moms to Lose Weight

NEW YORK—New moms may be better able to return to their pre-pregnancy weight by exclusively breast-feeding their infants, according to new research.“The practice of exclusive breast-feeding helps mothers lose the weight accumulated during pregnancy and do that faster compared to those who don’t practice exclusive breast-feeding,”

Dr. Alex Kojo Anderson, of the University of Georgia in Athens, told Reuters Health.Anderson and colleagues compared pre-pregnancy and at-delivery weight, with weight at 12 weeks after delivery, among 24 mothers, aged 19 to 42 years. Seventeen of these new moms exclusively breast-fed their infants, while nine mothers mixed-fed their infants, using formula or a combination of formula and breast milk.According to the findings, published online in the International Breast-feeding Journal, during the first 4 weeks after delivery, mothers in the mixed-feeding group lost more of their at-delivery weight than did mothers who exclusively breast-fed.

However, from 8 to 12 weeks, this trend reversed.When Anderson’s team compared the women’s post-pregnancy weight loss according to their pre-pregnancy weight, mothers who exclusively breast-fed lost more weight at 2-, 4, 8-, and 12-weeks after delivery than did mothers in the mixed-feeding group.This weight loss trend was evident in spite of the greater caloric intake and lower activity level among breast-feeding mothers, compared with mixed-feeding mothers, the investigators found.Moreover, “the trend in percent body fat loss was statistically significant among exclusive breast-feeding mothers and not the other group of mothers,” Anderson added.“

Our results provide further evidence that exclusive breast-feeding promotes greater weight loss than mixed feeding among mothers even in the early postpartum period,” Anderson and colleagues say. Encouraging mothers to exclusively breastfeed their infants is one way to help these women avoid becoming overweight or obese, they conclude.

Source: International Breastfeeding Journal, August 2008

Last UpdatedSep 24, 2008